Table of Content

10 February 2007, Volume 18 Issue 02

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Articles

Dynamics of litter decomposition and phosphorus and potassium release in Jinggan g Mountain region of Jiangxi Province, China.

LI Hai-tao;YU Gui-rui;LI Jia-yong;LIANG Tao;CHEN Yong-rui

2007, 18(02):  233-240 . 

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By using litter bag method, a 2-year experiment was made to study the dynamics of litter decomposition and phosphorous and potassium release of Castanopsis eyrei-dominated evergreen broad-leaved forest (EBF), Pinus taiwanensis, Cyclobalanopsis nubium and Castanopsis fabri conife-rous and broad-leaved mixed forest (CBF), and Rhododendron simiarum-dominated mountainous dwarf forest (MDF) in Jinggang Mountain region of Jiangxi Province, China. In each forest, litter bags were placed on soil surface (aboveground treatment, AG) and at the depth of 10 cm (below-ground treatment, BG). An inverse exponential relationship was found between litter decay rate and time for each of the three forests. The average value of the litter mass loss of AG and BG was 50.6% for EBF, 41.7% for CBF, and 40.13% for MDF by the end of first year, and 60.95% for EBF, 57.06% for CBF, and 56.60% for MDF by the end of second year, indicating that the litter decomposition of the forests was faster in first year than in second year. The annual litter loss decreased in the order of EBF>CBF>MDF, and that of AG was significantly higher than that of BG in first year but no significant difference was found in second year. According to the model simula-tion by Olson’s exponential function, it might take 6.8—9.9 years to reach 95% of decay (t_0.95) for the forests investigated, compared with 8—17 years for warm temperate forests and 2-8 years for south subtropical forests. The t_0.95 value of the three test forests increased in the order of EBF<CBF

Dynamics of soil water under Vernicia fordii plantation in hilly red soil region of Southern China

HUANG Zhi-gang^1,2; CAO Yun¹; OUYANG Zhi-yun¹; TU Nai-mei³; ZHENG Hua¹

2007, 18(02):  241-246 . 

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By using time domain reflectometry (TDR), a fixed-position monitoring was made on the dynamic characteristics of soil water under Vernicia fordii plantation in the hilly red soil region of Southern China. The results showed that there was a significant difference in the soil water storage among different months, and the dynamics of soil water could be described as the phases of accum-ulation, depletion, and stabilization. Soil water had a significant variation in its vertical distribution, and the variation pattern differed in different seasons. Significant correlations existed between soil water storage and meteorological factors such as relative humidity (RH), air temperature (t), vapor pressure deficit (VPD) and rainfall (R) (P<0.05). After rain, soil water loss had a significant hyperbolic correlation with drought duration, while soil water storage had a significant linear negative correlation with this duration (P<0.05). With the extension of drought duration after rain, soil water loss tended to vary gently with increasing soil depth.

ISSR analysis on genetic diversity of endangered relic shrub Sinocalycanthus chinensis

JIN Ze-xin;LI Jun-min

2007, 18(02):  247-253 . 

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By using inter-simple sequence repeat (ISSR) markers technique, this paper studied the genetic diversity of ten populations of endangered relic shrub Sinocalycanthus chinensis. The results showed that at species level, the percent age of polymorphic loci (P) was 73.08%, Shannon’s in-dex (h) was 0.3097, and Nei’s gene diversity (I) was 0.1987, indicating a high level of genetic diversity, but at population level, they were 23.65%, 0.1251 and 0.0839, respectively, suggesting a low level of genetic diversity. The analysis of molecular variance (AMOVA) demonstrated that there was a relatively high level (57.11%) genetic variation among the populations, with the gene differentiation coefficient (G_st) and gene flow being 0.5779 and 0.3651, respectively. The high genetic differentiation among populations and the low genetic diversity within populations could be attributed to the habitat fragmentation and the limited gene flow among populations. Through cluster analysis, the ten populations of S. chinensis were classified into two groups, with the eight populations in Lin’an City forming a group and other two in Tiantai County forming another group.

Age structure and growth characteristic of Castanopsis fargesii population

SONG Kun¹; DA Liang-jun¹; YANG Tong-hui²; YANG Xu-feng¹

2007, 18(02):  254-260 . 

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In this paper, the age structure and growth characteristics of Castanopsis fargesii population in a shade-tolerant broadleaved evergreen forest were studied, aimed to understand more about the regeneration patterns and dynamics of this population. The results showed that the age structure of C. fargesii population was of sporadic type, with two death peaks of a 30-year gap.This population had a good plasticity in growth to light condition. Because there were no significant differences in light condition under the canopy in vertical, the saplings came into their first suppression period when they were 5—8 years old, with a height growth rate less than 0.1 m·a^-1 lasting for 10 years. The beginning time of the first growth suppression period was by the end of the first death peak of the population, and the ending time of the first growth suppression period was at the beginning of the second death peak of the population, demonstrating that growth characteristic was the key factor affecting the age structure of C. fargesii.

Indirect effects of precipitation on litter decomposition of Quercus mongolica

LI Xue-feng^1,2; HAN Shi-jie¹; ZHANG Yan¹

2007, 18(02):  261-266 . 

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The effect of precipitation variation on chemistry of Quercus mongolica leaf litters was ex-amined by analyzing litters of Mongolia oak saplings under 4 precipitation gradients, and the decom-posing process of these leaf litters in Q. mongolica dominated forest was assessed using litter bag method. The results showed that under less precipitation, the litter had a higher decomposition rate , and its N, P and K mineralized quickly. The initial concentrations of N, P, and K increased, while that of lignin decreased significantly. With increasing precipitation, the mineralization rates of N, P and K in litter decreased. Its initial N concentration decreased, while the relative content of lignin increased. The mass loss patterns of four type litters fitted exponential model, and the decom-position rate could be well predicted by their lignin/N ratio. The decomposition rate of the litters with higher lignin and lower N was best related to their N concentration, while that of the litters with lower lignin and higher N was strongly correlated with their lignin concentration. It was proved that precipitation had a significant effect on the litter substrate quality of Q. mongolica, and thus, changed the decomposition process of the litter indirectly.

Optimal disposition of water conservation forests in watershed

CHEN Xiang-wei; WANG Wen-bo; XIA Xiang-you

2007, 18(02):  267-271 . 

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Based on the measurements of canopy interception, litter water-holding capacity and soil water storage of different stands in the Erdaoqiao watershed of upper Nenjiang River, the optimal disposition of water conservation forests in this watershed was approached by the method of an-alytical hierarchy process (AHP). The results showed that in this watershed, the optimal vegetation structure should be 24.86% of natural birch forest, 16.30% of natural Dahurian birch forest, 44.49% of natural broadleaved mixed forest, 10.88% of larch plantation,and 3.47% of grassland. After optimization, the water conservation capacity of the watershed could be improved obviously, with soil available and maximum moisture contents increased by 33.05% and 27.78%, respectively.

Soil hydro-physical properties under broadleaved Korean pine and dark coniferous forests on northern slope of Changbai Mountains

YANG Hong^1,2; LI Zhong¹; PEI Tie-fan¹; WANG An-zhi¹; JIN Chang-jie¹; ZHU Jiao-jun¹

2007, 18(02):  272-276 . 

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The measurement of soil hydro-physical properties under broadleaved Korean pine and dark coniferous forests on the northern slope of Changbai Mountains showed that under these two for-est types, soil bulk density and porosity had the same variation trend with increasing soil depth, i . e ., bulk density and capillary porosity increased, while total porosity and non-capillary porosity decreased. The average bulk density, total porosity, capillary porosity and non-capillary porosity in 0—100 cm soil layer were 1.41 g·cm^-3, 52.31%, 46.11% and 6.20% under broadleaved Korean pine forest, and 0.98 g·cm^-3, 50.65%, 40.32% , 10.33% under dark coniferous forest, respectively. Owing to the differences in soil hydro-physical properties, the water storage capacity in 0—100 cm soil layer was 619.89 t·hm^-2 under broadleaved Korean pine forest, but 1 033.05 t·hm^-2 under dark coniferous forest. For these two forests, their soil water characteristic curves were consistent with the general one.

Microelement contents of litter, soil fauna and soil in Pinus koraiensis and broad-leaved mixed forest

YIN Xiu-qin¹; LI Jin-xia^1,2; DONG Wei-hua¹

2007, 18(02):  277-282 . 

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The analysis on the Mn, Zn and Cu contents of litter, soil fauna and soil in Pinus ko-raiensis and broad-leaved mixed forest in Liangshui Natural Reserve of Xiaoxing’an Mountains showed that the test microelement contents in the litter, soil fauna and soil all followed the sequence of Mn>Zn>Cu, but varied with these environmental components, being in the sequence of soil>litter>soil fauna for Mn, soil fauna>litter and soil for Zn, and soil fauna>soil>litter for Cu. The change range of test microelement contents in litter was larger in broad-leaved forest than in coniferous forest. Different soil fauna differed in their microelement-enrichment capability, e . g ., earthworm, centipede, diplopod had the highest content of Mn, Zn and Cu, respectively. The contents of test microelements in soil fauna had significant correlations with their environmental background values, litter decomposition rate, food habit of soil fauna, and its absorbing selectivity and enrichment to microelements. The microelements contained in 5—20 cm soil layer were more than those in 0—5 cm soil layer, and their dynamics differed in various soil layers.

Species diversity of Brasenia schreberi community in different habitats

GAO Bang-quan; ZHANG Guang-fu; CHEN Hui-yan

2007, 18(02):  283-287 . 

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By using Braun-Blanquet Cover Abundance Scale method, the species diversity of Brase-nia schreberi community in Dongshan Town (Suzhou City, Jiangsu Province) and Zhuantang Town (Hangzhou City, Zhejiang Province) was studied, and the results showed that in these two towns, B. schreberi community was of simple species composition and relatively low species diversity. The Shannon-Wiener diversity index, Simpson ecological dominance index, and community evenness in-dex all increased obviously when the habitat shifted from pond center to bank nearby. B. schreberi community was similar in the same type habitats of these two towns, and of much more similarity in pond center than at bank nearby. Compared with Zhuantang Town, Dongshan Town had a greater difference of B. schreberi community between the two habitats.

Regional evapotranspiration of different land covers based on remote sensing

HE Yan-bo¹; Z. Su²; L. Jia³; WANG Shi-li⁴

2007, 18(02):  288-296 . 

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In this paper, surface energy balance system (SEBS) was extended into a regional daily evapotranspiration (ET) estimation model based on remote sensing data, and the extended SEBS was applied to estimate the regional daily ET of Huanghe-Huaihe-Haihe rivers region in Northern China Plain by using MODIS/TERRA data. An analysis was made on the estimated daily ET char-acteristics of different land covers in the study area by using the spatial analysis module of ArcGIS. Since there were no field observations of ET on each land cover, the estimated daily ET of different land covers was compared with each other, taking the data on April 17, 2001 as an example. The results showed that the regional daily ET estimated by SEBS was reasonable. Wetland and cultivated land had the highest daily ET value, followed by forest-, bush- and grassland, and waste land. The characteristics of the daily ET over these land covers were accorded with the existing knowledge of ET over this region, and coincident to the results of previous work in this area. It was interesting that the residential area also had a higher ET value, which was explained as the higher ET of the land use types, e . g ., water body, street trees, and grass parcels in the resident areas within the pixel scale. The spatial inhomogeneity of ET among the forest-, bush-, grass- and cultivated land covers were caused by the spatial inhomogeneous soil water content under these land covers, and the spatial inhomogeneity of ET over cultivated land could be a potential indicator of making reason-able and effective irrigation schedule for the farmland. The limitations of using SEBS model in daily ET estimation were discussed, especially the possibility of underestimating the ET over water body and wetland covers due to the unsuitable surface parameterization scheme for these land types in the model.

Time series analysis of soil water on sloping land in red soil hilly region

WANG Xiao-yan^1,2; CHEN Hong-song¹; WANG Ke-lin¹; FU Wei¹; XIE Xiao-li¹

2007, 18(02):  297-302 . 

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Based on time series analysis, the correlation between soil water and precipitation on the sloping land in red soil hilly region under two land use modes was studied from March to September, 2002—2004. The results showed that precipitation was not an autocorrelation series, while soil water at the depths of 10, 30, 50, 70 and 90 cm was an autocorrelation series with 30—45 days of time correlation range. Precipitation and land use mode were the main factors affecting the correl-ation of soil water and precipitation. The effect of precipitation weakened gradually with increasing soil depth. This effect lasted 7—8 days in upper soil layers (0—10 and 0—30 cm), but no marked regularity was observed in deeper soil layers. 2—3 days after raining, precipitation had the most prominent effect on soil water in 0—100 cm soil layer. The correlation time range was 1—3 days shorter in dry season than in wet season. When it didn’t rain more than 5 days, the water content in topsoil would decrease, and even, lead to seasonal drought. Compared with farmland, tea plantation had a weaker correlation between soil water and precipitation in surface soil, but a stronger and more persistent correlation in soil layers below 50 cm.

Effects of land use and management practice on farmland soil quality in Yanhuai basin of Beijing

ZHANG Xin-yu; CHEN Li-ding; FU Bo-jie; LI Qi; QI Xin; MA Yan

2007, 18(02):  303-309 . 

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In April 2005, a total of 41 soil samples were collected from the sandy loam soil (Usto-chrepts) under orchard, vegetable, corn (Zea maize L.) and soybean (Glycine max L.) in Yan-huai basin of Beijing, and their physical, chemical,and biological properties were analyzed. The results showed that the contents of soil organic carbon (SOC), total nitrogen (TN) and total phos-phorus (TP) in vegetable field, orchard field, and high-input corn field were obviously higher than those in soybean field and mid- and low-input corn fields. In these fields, SOC content varied from 7.67 to 10.00 g·kg^-1, TN content varied from 0.75 to 1.12 g·kg^-1, and TP content varied from 0.63 to 1.00 g·kg^-1. Soil available phosphorus (AP) content and electric conductance (EC) were significantly higher in vegetable field than in other fields, while no significant differences in soil physical properties were observed among the four land use types. The soil quality index of orchard and vegetable fields was 0.525 and 0.503, respectively, being higher than those of corn and soybean fields (0.417—0.494). Vegetable field had the highest efficiency of soil nutrients, but non-point source pollution risk should be minded. For soybean field and mid- and low- input corn fields, intensive management should be practiced to improve their soil quality.

Arsenic accumulation in different agricultural soils in Shouguang of Shandong Province

ZENG Xi-bai; LI Lian-fang; BAI Ling-yu; MEI Xu-rong; YANG Jia-bo; HU Liu-jie

2007, 18(02):  310-316 . 

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The study on the soil arsenic (As) accumulation under different types of agricultural use in Shouguang of Shandong Province showed that farmland soils had an average As content of 9.63 mg·kg^-1, with the highest being 15.15 mg·kg^-1. Compared with the local background value (9.3 mg As·kg^-1), 53.1% of soil samples was detected as As enrichment. The soil As content was high in the west, east and north parts of Shouguang, relatively lower in the middle part, and the lowest in the south part. Different agricultural use had an obvious effect on the soil As content, which was decreased in the order of wheat/maize land>cotton field>protected vegetable land>un-covered vegetable land. Such a difference in soil As content was mainly affected by agricultural ac-tivities. With the increasing year of vegetable planting, soil As content had an increasing trend, be-cause the As input from pig dung and chicken feces was the main source of soil As in protected ve-getable land. Soil As enrichment could be reduced to some degree by applying soybean cake fertilizer.

Calculation of crop evapotranspiration in greenhouse

CHEN Xin-ming^1,2; CAI Huan-jie¹; LI Hong-xing¹; WANG Jian¹; DU Wen-juan²

2007, 18(02):  317-321 . 

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Based on Penman-Monteith equation, a simplified formula for calculating the crop evapo-transpiration in greenhouse was deduced by introducing the parameter of crop canopy height and modifying the item of aerodynamics related to wind velocity. The deductive procedure was analyzed theoretically, and the formula was validated with meteorological data. The results showed that the modified Penman-Monteith equation had a higher precision of prediction, with a relative deviation of 4.7%—17.1% and 11.1% on average, being suitable to calculate the crop evapotranspiration in greenhouse.

A dynamic knowledge model for designing suitable scheme of rapeseed sowing and transplanting

ZHU Yan; CAO Wei-xing; TIAN Yong-chao; YAO Xia

2007, 18(02):  322-326 . 

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Based on the sum-up and abstraction of the relationships of rapeseed growth characters with ecological environment, cultivar type, production condition and yield target, a dynamic knowl-edge model was developed by using knowledge engineering and system modeling method, which could be used for designing a suitable sowing and transplanting scheme of different rapeseed varieties under different spatial and temporal environments. Case studies on the knowledge model with the data sets of three different sites, nine different variety types, and two different sowing styles indicated a good performance of the model system in decision-making, explanation, and wide applicability.

Effects of foliage spraying sodium bisulfite on photosynthetic physiological characteristics of Citrus sinensis with sulphur deficiency

CHEN Ping-zhao;HE Mei;YUAN Xiao-chun

2007, 18(02):  327-332 . 

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The study with solution culture showed that Citrus sinensis plants with sulphur deficiency and with sulphur deficiency plus foliage spraying sodium bisulfite (NaHSO₃) halfway had notably decreased photosynthetic pigment content, soluble protein content, net photosynthetic rate (P_n), initial fluorescence (F_o), maximum fluorescence (F_m), photochemical efficiency (F_v/F_m) and el-ectron transmit rate (ETR), compared with those having normal sulphur supply. After 35 days of growth, their photosynthetic pigment content decreased by 23.45% and 11.32%, and soluble protein content decreased by 43.43% and 25.30%, respectively, while no significant differences were observed between the plants with sulphur deficiency plus foliage spraying NaHSO₃ throu-ghout the experiment and those having normal sulphur supply, suggesting that foliage spraying NaHSO₃ could be an effective way to supply sulphur element to the C. sinensis with sulphur deficiency, but hard to rectify sulphur deficiency symptom when the plants suffered from a severe sulphur deficiency stress for a long time.

Effects of free-air CO₂ enrichment (FACE) on dry matter production and allocation in wheat

YANG Lian-xin¹; WANG Yu-long¹; LI Shi-feng¹; HUANG Jian-ye¹; DONG Gui-chun¹; ZHU Jian-guo²; LIU Gang²; HAN Yong²

2007, 18(02):  339-346 . 

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A free-air CO₂ enrichment (FACE) experiment was conducted in 2001—2003 to study the effects of predicted higher CO₂ levels on the dry matter (DM) production and allocation in win-ter wheat variety Ningmai 9. The results showed that under FACE, the DM production had an in-crease of 10.8%, 31.6%, 40.5% and27.2% during the growth periods from sowing to wintering (Period 1), wintering to jointing (Period 2), jointing to booting (Period 3), and booting to heading (Period 4), respectively, but a decrease of 5.5% in the period from heading to grain maturity (Period 5). As a result, the final total biomass at maturity was increased by 13.6%. FACE had no significant effect on leaf area index (LAI) and net assimilation rate (NAR) in Period 1, but made the LAI in Period 2 increased obviously, and the NAR decreased dramatically in Period 3. Under FACE, the proportion of leaf to total aboveground DM decreased, while that of stem (including sheath) to total above-ground DM showed an opposite trend in the whole growth period. The percentage and total amount of soluble sugar and starch in the stem at grain-filling stage were also increased obviously under FACE.

Effects of irrigation amount at seedling stage on physiological characteristics and yield of peanut

YAN Mei-ling^1,2; JIAO Yan-lin²; LI Xiang-dong¹; LIU Zhi-jian²; TANG Xiao¹; LIN Ying-jie¹

2007, 18(02):  347-351 . 

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Taking two peanut varieties with different drought-resistance Luhua 11 and Nongda 818 as test crops, the effects of different irrigation amount at seedling stage on their physiological char-acteristics and yield were studied from 2003 to 2004. The results showed that with decreasing irrig-ation amount, the leaf photosynthesis rate of test varieties decreased, while malondialdeyde (MDA) content increased. Watering 60—80 mm (suitable drought) enhanced the activities of superoxide dismutase (SOD), peroxidase (POD) and catlase (CAT), and increased the content of soluble protein. After re-watering by the end of treatments, the activities of SOD, POD and CAT and the contents of soluble protein and MDA decreased significantly, while photosynthesis rate increased obviously. The pod and kernel yield decreased with decreasing irrigation amount, and Luhua 11 had a greater loss than Nongda 818, indicating that Nongda 818 was more drought-tolerant than Luhua 11. It was suggested that under water-saving culture, the irrigation amount at seedling stage could not be less than 80 mm for Luhua 11, and less than 60 mm for Nongda 818.

Effects of weak light on photosynthetic characteristics and chloroplast ultrastructure of non-heading Chinese cabbage

HUANG Jun; GUO Shi-rong; WU Zhen; LI Shi-jun

2007, 18(02):  352-358 . 

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The study with two varieties of non-heading Chinese cabbage shade-tolerant ‘Aiwang’ and shade-sensitive ‘Lüyou’ showed that after shading, the total chlorophyll and chlorophyll b con-tents of ‘Aiwang’ went up greatly, but the net photosynthetic rate (P_n), light compensation point (LCP), light saturation point (LSP), apparent quantum yield (AQY) and carboxylation efficiency (CE) of both ‘Aiwang’ and ‘Lüyou’ all went down, and the decline of all test parameters except LCP was slighter for ‘Aiwang’ than for ‘Lüyou’. Under weak light condition, the PSⅡ of ‘Lüyou’ was injured, and as a result, the F_v/F_m, ETR, Φ_PSⅡ, and q_P of ‘Lüyou’ had a greater decline than those of ‘Aiwang’. In the chloroplast of ‘Lüyou’, cracks and foveolae appeared, most of stroma lamellae fractured, grana lamellae disaggregated, and mitochondria were nearly empty with the decrease of contents. In contrast, the chloroplast structure of ‘Aiwang’ was flawless, and its mitochondria grew well. It was suggested that weak light could damage the photosynthetic organization of plant, but different varieties showed different responses.

Effects of rice seedlings horizontal distribution on the dynamics of rice population, canopy light transmittance rate and panicle characteristics

CHEN De-chun; YANG Wen-yu; REN Wan-jun

2007, 18(02):  359-365 . 

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The study with stronger tillering hybrid rice ‘D-you 527’ showed that the more the irreg-ularity of the seedlings horizontal distribution, the more colony stem-tillers the plants would have. Such a difference was significant 34 days after transplanting, but not significant at full heading stage. After transplanting, the trend that the variation coefficient increased with increasing irregu-larity of horizontal distribution presented gradually, and the difference became significant after joint-ing stage. Comparing with uniform distribution, an irregular horizontal distribution of the seedlings could benefit the canopy light transmittance rate and the panicle characteristics of rice.

Effects of boron on indole-3-acetic acid transportation in intact Phaseolus aureus plant

JIAO Xiao-yan; YANG Zhi-ping; ZHAO Rui-fen; WANG Li-zhi

2007, 18(02):  366-370 . 

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With intact Phaseolus aureus plant as test material, this paper studied the effects of bo-ron deficiency on its axillary bud growth and polar auxin transportation. The results showed that bo-ron deficiency induced axillary bud growth significantly, while applying indole-3-acetic acid (IAA) could suppress the axillary bud growth induced by the decapitation of boron sufficient plant. When the plant deficient in boron was decapitated, applying IAA could delay the axillary bud growth. Compared with boron sufficient plant, the plant deficient in boron had an inhibited auxin basipetal movement in terms of the shorter distance of ³H-IAA peak from apex, and less total radioactivity de-tected in stem. No radioactivity was found in the axillary buds in any of the treatments, suggesting that the basipetal IAA transportation in stem rather than the IAA accumulation in bud was required for the inhibition of bud growth. A 24 h boron supply to the boron deficient plant could restore its ³H-IAA transportation.

Effects of soil water content on H₂O and CO₂ exchange in tomato leaves in different seasons

GAO Fang-sheng^1，2; XU Kun¹; WANG Lei³; SU Hua¹; XU Li-gong¹

2007, 18(02):  371-375 . 

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With tomato variety “L402” as test crop, this paper studied its photosynthetic and tran-spiration characteristics in different seasons under different soil water contents. Three treatments were installed, i . e ., 80% (Ⅰ), 65% (Ⅱ) and 50% (Ⅲ) soil water content. The results showed that when cultivated in spring, the photosynthetic rate (P_n) and transpiration rate (T_r) of tomato leaves were the highest in treatment Ⅰ, followed by treatmentsⅡ and Ⅲ, while the water utilization efficiency (WUE) was the highest in treatment Ⅱ. The decrease of soil water content changed the diurnal variations of P_n and T_r significantly, and aggravated the midday depression of photosynthesis. The tomato growing in winter had the lowest P_n and T_r in treatment Ⅲ, while no difference was observed between treatments I and II.No midday depression of photosynthesis was found among the three treatments. The WUE was the highest in treatment Ⅲ, and the lowest in treatment Ⅰ. All of these suggested that the tomato plants cultivated in different seasons had differ-ent responses to soil water content. The diurnal variations of their P_n and T_r were significantly differ-ent, and the P_n and T_r of spring tomato were significantly higher than those of winter tomato under the same soil water content.

Effects of D-arginine on polyamine content and anaerobic respiration metabolism of cucumber seedling roots under hypoxia stress

LI Jing; HU Xiao-hui; GUO Shi-rong; JIA Yong-xia; DU Chang-xia

2007, 18(02):  376-382 . 

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By the method of solution culture, this paper studied the effects of D-arginine on the seedling roots polyamine content and anaerobic respiration metabolism of two cucumber (Cucumis Sativus L.) cultivars Zhongnong No.8 and Lübachun No.4 differed in hypoxia tolerance. The re-sults showed that under hypoxia stress, the putrescine (Put), spermidine (Spd) and spermine (Spm) contents in the seedling roots of test cultivars increased significantly, and anaerobic respira-tion accelerated. The ethanol fermentation activity was higher in the seedling roots of hypoxia-tolerant cultivar Lübachun No.4 than in those of hypoxia-sensitive cultivar Zhongnong No.8, while lactate fermentation activity had an opposite trend. Comparing with treatment hypoxia, hypoxia plus D-arginine decreased the Put, Spd and Spm contents in roots significantly, enhanced the activities of alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH) and the contents of ethanol and lactate, and inhibited plant growth. Exogenous Put application lessened the effects of D-arginine. Higher level of polyamines in roots could have great benefits for cucumber seedlings to improve their resistance to hypoxia stress.

Effects of DMPP-compound fertilizer on greenhouse celery growth and nutritional quality

WU Shao-fu^1,2;WU Liang-huan¹;YIN Yi-meng³;YANG Shu-dong³;CHEN Xian-you¹

2007, 18(02):  383-388 . 

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A field study with greenhouse celery (Apium graveolens L.) showed that compared with basal application of ordinary compound fertilizer, one-time basal application of DMPP-compound fertilizer (ENTEC^®, 12-12-17) at the rates of 67.5 kg N·hm^-2 and 54.0 kg N·hm^-2 increased the yield by 5.78% and 10.14%, respectively. The application of ENTEC^® also improved the nu-tritional quality of edible parts, e . g ., the Vc, amino acid, soluble sugar, N and P contents in-creased, while nitrate content decreased. Compared with basal plus side dressing applications, appropriately reducing the application rate and times of ENTEC^® had more beneficial effects on celery yield and quality, and reduced the production costs. ENTEC^® could suppress the transf-ormation of soil NH₄⁺-N to NO₃^--N effectively, and thus, its application could retain soil residual N more in NH₄⁺-N than in NO₃^--N form after celery harvested,resulting in a reduction of nitrate leaching.

Mechanisms of high temperature-induced Pseudoperonospora cubensis resistance of cucumber

SHI Yan-xia¹; LI Bao-ju¹; LIU Xue-min²

2007, 18(02):  389-394 . 

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This paper studied the effects and control efficiency of high temperature on the pathoge-nicity and occurrence of Pseudoperonospora cubensis. The results showed that the P. cubensis resist-ance of cucumber was most obvious after treated at 40 ℃ for 2 h or at 45 ℃ for 1 h, with the con-trol efficiency being 58.40% and 45.81% at the forth day, and 39.35% and 37.65% at the sixth day after P. cubensis inoculation, respectively. Under high temperature, the activities of peroxidase (POD), phenylalanine ammonia lyase (PAL), chitinase (Cht), β-1,3-glucanase (Glu) in cucumber leaf were significantly higher, and large amount of lignin was deposited on the cell wall of leaf tissue, indicating that after treated with high temperature, cucumber plant manifested an induced P. cubensis resistance.

Changes of oviposition preference of diamondback moth after experiencing a neem-based repellent/deterrent BIOACT-T^TM

LI Yue-hong; LIU Shu-sheng

2007, 18(02):  395-399 . 

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For the adults of phytophagous insects, their experience of non-host plant-originated re-pellent/deterrent may produce habituation or induced preference to it. In this study, the experi-enceinduced changes in oviposition responses of diamondback moth Plutelle xylostella L. to a neem-based repellent BIOACT-T^TM EC508 were examined in laboratory. 2—6 days old female moths were offered with 2—6 times or 2—6 days experience of the repellent, and their ovipostion preference to untreated and BIOACT-treated Chinese cabbages were evaluated. The results showed that BIOACT had a strong repellent effect to all of the naive 2—6days old females, that only laid approximately 10% of their eggs on BIOACT-treated plants. As for the 2, 4 and 6 days old females who experienced 2 times or 2 days, 4 times or 4 days, and 6 times or 6 days of BIOACT, their mean oviposition rate on BIOACT-treated plants increased to 17%, 21%—24%, and 29%, re-spectively,demonstrating that this experience of the females induced their habituation or preference to BIOACT, and consequently, the repellent effect of BIOACT decreased. However, there were substantial variations in the experience-induced changes of oviposition preference among the individuals of the moth.

Effects of Tagetes erecta extracts on glutathione S-transferase and protease activities and protein content in Tetranychus viennensis

SHI Guang-lu¹; WANG You-nian¹; WANG Hong-lei²; ZHAO Li-lin²; LIU Su-qi³; CAO Hui³; YU Tong-quan¹; LU Ping¹

2007, 18(02):  400-404 . 

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With in vivo and in vitro Tagetes erecta roots under light and dark as test materials, this paper studied the effects of their extracts on the glutathione S-transferase and protease activities and protein content in Tetranychus viennensis. The results showed that the chloroform extract of T. erecta roots had the highest light-activated activity, followed by water extract, and methanol extract. After treated with chloroform extract, the glutathione S-transferase and protease activities in T. viennensis increased markedly, while its protein content decreased obviously. The variation degree of T. viennensis protease activity and protein content was significantly higher when the chloroform extract came from the T. erecta roots under light, suggesting that there existed active matters in the extract, which could promote the activation of protease, and thus, the decomposition of protein in T. viennensis. The bioactivity of T. erecta metabolites was mainly of light-activated one.

Abundance and biomass of meiobenthos in Southern Yellow Sea in winter

ZHANG Yan¹; ZHANG Zhi-nan¹; HUANG Yong^1,2; HUA Er¹

2007, 18(02):  411-419 . 

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A two cruises investigation on the meiobenthos in the continental shelf of Southern Yellow Sea was made in January 2003 and January 2004. The results showed that the average abundance of meiobenthos was (954.20±269.47) ind·10 cm^-2 and (1 186.12±486.07) ind·10 cm^-2, and the biomass was (954.38±403.93) μg·10 cm^-2 and (1 120.72±487.21) μg·10 cm^-2 in January 2003 and January 2004, respectively, with no significant difference observed. A total of twenty meiobenthic groups were identified. Free-living marine nematodes was the most dominant group in abundance, with a relative dominance of 87% in 2003 and 90% in 2004, followed by benthic harpacticoids copepoda, polychaeta and kinorhyncha. In terms of biomass, the dominant groups were nematoda (34%—38%), polychaeta (25%—33%), ostracoda (9%—22%) and copepoda (8%). 96.64% of the meiobenthos distributed in the top 0—5 cm of sediment, while 72.48% of nematode and 89.46% of copepoda were in the top 0—2 cm of the sediment. Meiob-enthos biomass had significant correlation with the sand and silt contents of sediment and the content of Chla. The species composition and biodiversity analyses of six representative stations indicated that there were three meiobenthos communities in the study area, i . e ., inshore, cold waters mass, and transitional communities.

Effects of different concentration ammonium-N on Hydrilla verticillata antioxidant enzymes under Cd stress

XU Qiu-jin; JIN Xiang-can; WANG Xing-min; HU Xue-wen; CHEN Shu-qin; YAN Chang-zhou

2007, 18(02):  420-424 . 

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In this paper, submersed plant Hydrilla verticillata was cultivated in a 1/10 Hoagland culture medium added with different concentration NH₄⁺-N (0, 0.5, 2.0, 4.0 mg·L^-1) and 10 mg·L^-1 cadmium to study the effects of NH₄⁺-N on H. verticillata growth and its antioxidant en-zyme system under Cd stress, and approach the degradation mechanism of submersed macrophyte in eutrophic and polluted water bodies. The results showed that under 10 mg·L^-1 Cd stress, the chlorophyll content of H. verticillata decreased obviously, and SOD and POD activities increased first but declined then. NH₄⁺-N accelerated the stress effect of Cd. Under 0.5 h joint stress of Cd and NH₄⁺-N, SOD activity increased significantly, while such an increase needed 3 hours under single Cd stress. Relative to chlorophyll and protein, antioxidant enzyme system was an early sensi-tive index, and SOD was more sensitive than POD. After two days exposure to Cd plus NH₄⁺-N, H. verticillata was mainly stressed by Cd, and NH₄⁺-N stress could be neglected.

Dynamics of Cd adsorption on rice seedlings root surface with iron coating and Cd uptake by plant

LIU Hou-jun^1,2; HU Xiang-bai¹; ZHANG Jun-ling¹; ZHANG Fu-suo¹

2007, 18(02):  425-430 . 

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In a water culture experiment, rice seedlings were grown in a nutrient solution containing 10 μmol Cd·L^-1, and harvested after different durations of growth. Two treatments were installed, i . e ., adding 50 mg Fe²⁺·L^-1 to induce the formation of iron coating on seedlings root surface (treatment Fe₅₀), and the control. The study on the dynamics of the Cd adsorption on root surface and of the Cd uptake by plant showed that both in the treatment Fe₅₀ and in the control, the amount of adsorbed Cd on root surface was the highest in the first 2 hours, decreased dramatically then and remained relatively stable thereafter, while the Cd concentrations in roots and shoots increased slow-ly within the first 8 hours and rapidly then. The increment of Cd concentrations in roots and shoots was smaller in treatment Fe₅₀ than in the control, and the amounts of adsorbed and absorbed Cd also showed the same picture, suggesting that the iron coating on rice root surface had little effect on the dynamics of Cd content in different parts of rice seedlings, and the reduced Cd uptake in treatment Fe₅₀ was probably relevant with the Fe concentration in roots.

Effects of dissolved organic matter on phenanthrene adsorption by soil

XIONG Wei; LING Wan-ting; GAO Yan-zheng; LI Qiu-ling; DAI Jing-yu

2007, 18(02):  431-435 . 

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This paper studied the effects of exotic and native dissolved organic matter (DOM) on the phenanthrene adsorption by three soils differed in soil organic carbon content (f_oc). The exotic DOM came from decayed rice straw, while the native DOM was extracted from the test soils. In all cases, the adsorption of phenanthrene by treated soils could be well described with linear-type mod-el, and there was a positive correlation between adsorption coefficient (K_d) and f_oc. Compared with the control, the K_d value of test soils after native DOM removed was increased by 7.08%—21.4%, and the increment (ΔK_d) was positively correlated with f_oc, indicating that the presence of soil native DOM impeded the phenanthrene adsorption by soil. The effects of exotic DOM on phenan-threne adsorption had a close relation with its added concentration in soil-water system. Within the range of 0—106 mg DOC·L^-1, the K_d value increased first, and then decreased with the increase of added exotic DOM concentration. Lower concentrations of added exotic DOM promoted the phe-nanthrene adsorption by soil, while higher concentrations (≥52 mg DOC·L^-1) of it obviously im-peded this adsorption. These effects of exotic and native DOM on soil phenanthrene adsorption were considered to be related to the association of phenanthrene with DOM in solution, and the ‘cumulative adsorption effect’ between soil solid and aqueous phases.

Research advance in seed germination of desert woody plants

CHANG Wei^1,2; WU Jian-guo²; LIU Yan-hong¹

2007, 18(02):  436-444 . 

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This paper reviewed the research methods of desert woody plants seed germination, and the effects of internal and external ecological factors on it. Most researchers use incubator and artifi-cial climate chamber to dispose the seeds, while field investigation was few involved. Seed dorman-cy is the important physiological factor affecting germination, while seed size, mass and color are closely correlated with its maturity and vigor. The poor permeability of seed capsule is a barrier that restrains the germination, which can be weakened or eliminated by shaving, cutting, treating with low temperature, and dipping in chemical reagent, etc. Seed water content has a close correlation with its storage life and water-absorbing capability. Suitable temperature is the prerequisite of seed germination, while changing temperature can accelerate the germination. Soil moisture content is a limiting factor, while illumination is not so essential to the seed germination of most desert woody plants. Sand-burying plays an important role in the seed germination through regulating illumina-tion, temperature, and soil moisture content. Salinity stress restrains the seed germination of desert woody plants observably. In further studies, the effects of multi-factors and the eco-physiological and molecular biological mechanisms of germination should be more concerned.

Research advances in vulnerability assessment of natural ecosystem response to climate change

ZHAO Hui-xia^1,2; WU Shao-hong¹; JIANG Lu-guang¹

2007, 18(02):  445-450 . 

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Climate change with global warming as the sign has been caught great attention by the governments, international organizations, and scientists in the world. Human society and natural e-cosystem are both exposed to climate change, and more and more people are waked up by its in-creasing harm. Vulnerability analysis and assessment are the key and basis for adapting and mitiga-ting climate change, being the highlight in the research fields of climate change and ecology in re-cent years. The vulnerability assessment of climate change is being carried out in various research fields and on different scales, and much progress has been made. This paper introduced the concept of vulnerability, and summarized the research progress in vulnerability assessment of climate change, with the focus on the frame and methodology of vulnerability assessment of natural ecos-ystem response to climate change. The existed problems and future prospects in this research area were also discussed.

Flight behaviors of Bemisia tabaci and corresponding IPM strategies

ZHOU Fu-cai¹; WNAG Yong¹;REN Shun-xiang²; ZHU Shu-de¹; ZHOU Ze-hua³

2007, 18(02):  451-455 . 

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Bemisia tabaci, a pest insect with stronger capabilities of flying and host plant-exploita-tion, is capable of flying 150 m high and over a distance as far as 7 km, but hardly flies higher than 0.5 m and long distance in foodabundant areas. B. tabaci has the characteristics of both searching-and migrating flying, which enable it to exploit and locate on suitable hosts. Up to now, no oogene-sis-flight syndrome of B. tabaci has been detected. Visual spectrum, air temperature and relative humidity, host quality, and wind speed are the main factors affecting the flight behavior of B. tabaci. In this paper, the flying capability of B. tabaci and the factors affecting its flight behavior were summarized, and the corresponding IPM strategies in the areas where B. tabaci could not overwintering in open field were discussed.

Horizontal subsurface flow constructed wetland models

WEN Yue;ZHOU Qi

2007, 18(02):  456-462 . 

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As a new treatment technology, constructed wetland plays an important role and has broad prospects in water pollution control and environmental restoration. Its designing artifice is get-ting progress owing its increasing application in wastewater treatment coupling with the increasingly strict water quality standards.From the aspects of hydrodynamics, contaminants degradation dynam-ics and parameters uncertainty, this paper gave a systematic review on the horizontal subsurface flow constructed wetland models, including load approach, regression equation, first-order k-C* model and its reformed forms, and dynamic mechanistic models. Based on the comparison of the assump-tions and methodologies of the models, the intrinsic relationships in the development of horizontal subsurface flow constructed wetland models were analyzed, and the main issues of their application in constructed wetland design were indicated, with the perspectives in this field discussed.

Molecular genetic diversity of Fujian domestic duck breeds

LI Hui-fang^1,2; LI Bi-chun¹; MA Yue-hui³; TANG Qing-ping²;CHEN Kuan-wei²; TU Yun-jie²

2007, 18(02):  463-466 . 

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By using 28 micro-satellite markers with better polymorphism, this paper studied the ge-netic diversity of four Fujian provincial domestic duck breeds Jinding, Putian black, Liancheng white, and Shanma. According to the alleles frequencies, the polymorphic information content, av-erage heterozygosity, anaqular genetic distance (D_A) and Nei’s standard genetic distance (D_S) for each breed were calculated. Based on D_A and D_S, four dendrograms were obtained by neighbor-joining (NJ) and UPGMA methods. The results showed that the average heterozygosity of the four duck breeds was 0.5353, indicating that the protection of the genetic diversity of these breeds should be strengthened. The orders of the two types of genetic distances among the breeds were accordant, and the dendrograms were the same, reflecting that much more micro-satellite loci should be adopted to obtain more universal conclusions when the genetic diversity was analyzed. The phy-logenetic relationships among the four duck breeds were in accordance with their economic types and ecological localities.

Geostatistic analysis of spatial pattern of Fruhstorferiola tonkinensis Will(Orthoptera: Catantopidae) nymphs

CHEN Qiang; WU Wei-jian; ZHANG Zhen-fei; LIANG Guang-wen

2007, 18(02):  467-470 . 

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By the methods of geostatistics, this paper studied the spatial pattern of Fruhstorferiola tonkinensis nymphs in mulberry fields of north Guangdong. The results showed that the semivario-gram of F. tonkinensis nymphs at all development stages could be described by spherical model, im-plying an aggregative distribution, and the range of their spatial correlation was 1.973, 1.968, 2.169, 2.302 and 4.307 m from 1st to 5th instars. Based on the information obtained from investi-gation site, the isoclines maps of the instars were created by the geostatistical software Surfer 8.0 with Kriging interpolation, and the resulting maps gave a clear indication about the spatial patterns of the instars.Unlike other locusts, the younger instars of F. tonkinensis had an aggregative distri-bution, while the elder ones were dispersive in distribution.