关键词: 农林用地, 广佛都市圈, 农林生态系统服务价值, 城市化

Abstract: Taking two cotton cultivars of high efficient genotype (HG) and low efficient genotype (LG) as test objects, a field experiment was conducted to study their photosynthesis and photosynthate accumulation and partitioning under low potassium (K) stress. Low K stress decreased the leaf net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), and plant biomass, promoted the partitioning of photosynthates to vegetative organs but decreased the partitioning ratio to reproductive organs, and thus, decreased the harvest index. There existed differences in the photosynthetic parameters between the two cotton cultivars. Whether K was applied or not, HG cultivar had higher P_n, T_r, G_s, and C_i, as compared with LG cultivar. There also existed differences in the biomass partitioning between the two cotton cultivars. The HG cultivar partitioned less biomass to vegetative organs but more to reproductive organs, and maintained a higher harvest index, while LG cultivar was in adverse, regardless of the K condition. The biomass of the two cotton cultivars had no significant difference at seedling stage and squaring stage, but the biomass of HG cultivar was higher than that of LG cultivar at bolling stage and boll opening stage. Moreover, the K use index of HG cultivar was higher than that of LG cultivar at bolling stage and boll opening stage. This study indicated that K application could improve the photosynthetic function of cotton leaf and the partitioning efficiency of photosynthates.

Key words: agriculture and forestry land, Guangzhou-Foshan Metropolitan Area （GFMA）., urbanization, agriculture and forestry ecosystem services value (AESV)