Differences Of Physiological Characterastics And Yield Traits Of Wheat Under Different Irrigation Conditions

In order to clarify the differences of physiological characterastics and yield traits of wheat under different irrigation conditions, a field experiment with three irrigation regimes, namely S1 (two irrigations,.before over-winter and at stem elongation), S2 (one irrigation at stem elongation) and S3 (two irrigations at stem elongation and grain filling respectively) was conducted on the Teaching and Demonstration Farm of Agricultural University of Hebei, Baoding, during 2003-2004, with field-grown winter wheat of two cultivars, Henong 859 and Yumai 49 as experimental materials. Yumai 49, a half-winter cultivar with high yield provided enough water and high fertility, was a main variety in Henan province, while Henong 859, a half-winter cultivar with strong drought-resistance, was a main cultivar in Hebei province. The main results were summarized as follows:1. Under water stress, leaf Chi content, Pn and gs decreased, while Ci increased. With the increasing of Ci, great amount of CO₂ was accumulated in intercellular space. As a result, dry matter production was also reduced which led to the decrease of grain yield. Comparing with Yumai 49, Henong 859 kept relatively higher Pn and TR, and the decrement of Pn and TR was smaller under water stress. These provided a basis for the higher yield of the cultivar Henong 859. The facts that there existed differences between the two cultivars in Pn and TR indicated that it was of significance to select wheat cultivars with high photosynthetic efficiency according to different water conditions.2. Under water stress, soluble protein content in leaves was reduced, and the fluctuation of soluble protein content of Henong 859 was smaller than that of Yumai 49. Also, soluble protein content in flag leaf was relatively sensitive to water stress comparing with the top 2nd leaf and the top 3rd leaf. Under water stress, soluble sugar, MDA and proline in different leaves were increased, and these two physiological indices of Henong 859 were obviously smaller than those of Yumai 49, no matter under serious stress as well as moderate stress. These showed that mere were no direct relations between the contents of soluble sugar and proline and drought-resistance of wheat.3. Plant heights, spike length and spike stalk length of S3 treatment with irrigation at grain filling stage was superior to those of S1 and S2 without irrigation at grain filling, especially for Yumai 49.4. Higher grain number per spike, 1000-grain weight, grain yield and economical...