Abstract: We examined the responses of morphological structure and dry matter distribution of spring wheat to drought stress in different developmental periods in 2018, with the mainly popularized variety of Yongchun No. 4 in Ningxia as the experimental material. There were six different irrigation treatments. The results showed that the treatment of no irrigation at all growth stages shortened the whole growth stage by 11 days. Drought in the tillering and jointing stages reduced lower stem segments of spring wheat spike, leaf area, and plant height, and advanced leaf yellowing. Water shortage at tillering stage had the strongest effect on leaf area, while water shortage at jointing stage had the most effect on plant height. Drought affected the accumulation and distribution of dry matter in spring wheat. When spring wheat was under drought stress at the tillering stage, the proportion of leaves in the total dry matter decreased by 6.6%, and the proportion of leaf sheath in the total dry matter increased by 9.0%. Compared with the control, when the spring wheat was under no irrigation at all growth stages, the spike length, spike number, spike grain number and thousand kernel weight were reduced by 5.9%, 43.4%, 9.6% and 7.6% respectively. Mild drought at tillering stage significantly decreased the wheat spike number, but increased the number of grains per spike and the thousand kernel weight by 9.2% and 4.7%. The drought during flowering to filling stage had the greatest effect on the thousand kernel weight, with a decrease of 17.4%.

Key words: saline-alkali ecosystem, cultivated land, remote sensing image interpretation, modified method.