Effect Of Different Irrigation Pattern On The Characteristics Of Grain Sink In Winter Wheat (Triticum AestivumL.)

In order to understand the mechanism of water saving and high yield cultivation of winter wheat, this research was concentrated on the carbon and nitrogen remobilization, the process of grain filling, the differentiation of endosperm cell, the metabolism of the starch and activities of the key enzymes relative to the sucrose biosynthesis. The program included five irrigation treatments: absence of water completely in the spring (CK), jointing water (Trl), upstanding and booting water (Tr2), jointing and anthesis water( Tr3 ), upstanding> booting > anthesis and filling water(Tr4) and a high grain yield winter wheat ( Triticum aestivum L.) variety "Laizhou 137" was used . The main results were given here:1. Generally with the increase of water supply the yield of winter wheat also increased in the severely drought region, but there were no obvious difference between the treatment of watering twice and four times in the spring, especially Tr3, which can not only increase the yield, but also improve the adsorption of water.2. The treatment of Tr3 had a higher thousand- grain- weight than that of Tr4 and there were no obvious difference on the number of endosperm cell among the five treatments, which implied that it was the process of differentiation and not the number that was sensitive to the water supply and the grain size was determined by the capability of sink.3.The characters of grain filling and sucrose accumulation were analysised. and the results showed that there were difference on the duration (T), the maximum rate (Max) and the average rate of grain filling (R) among the five treatments, the treatments of Tr4, Tr3, Tr2 had the same period of grain filling, but significantly longer than Trl CK. The trends of Max were Tr4> Tr3> Tr2> Trl) CK, and the trends of R were Tr3 > Tr4 > Tr2> Tr1) CK, which suggested that severely and sustained drought (Tr1l CK) decreased the duration of grain filling and the maximum rate, not the average rate. Water deficit in the upper layer of soil would increase the rate of grain filling, such as the treatment of Tr3.4. In the duration of grain filling, different treatment brought about different dynamic of carbon and nitrogen immobilization. With the decrease of water supply, more carbon and nitrogen assimilated before anthesis would transferred into grains to synthesis the sucrose and protein. Water saving could sustain a higher rate of grain filling.5.The activities of SS, ADPG-ppase and SSS (dry weight basis) reached their peaks at the early stage of grain growth, and decreased with the grain filling. Comparing with Tr4, weather CK or Trl, their activities of the three enzymes decreased obviously, but Tr2 and Tr3, which were watered twice had similar activities. It should be noted that the later especially, had a high activity of SS at the early stage of grain filling, and a high activity of SSS at the later stage, which suggested that water saving (water twice) had no side effect on these key enzymes, on the contrary, had a trend of increasing SS and SSS activities. There were no obvious difference between superior and interior grains and the difference would decrease with the water deficit..