| Controlling water pot experiment of the two varieties, Shangyu 397 and Suijing 3, with same growth period and different quality were studied in a rain-proof shelter. Soil water potential (SWP) was examined rigorously with negative pressure soil moisture tensiometer. Controlling water treatments (CWT) at–30-35kPa and–60--65kPa of SWP were carried out during tillering period, panicle formation period, 1-10days after heading, 11-20days after heading, 21-30days after heading and 1-30days after heading, respectively. The effects of soil moisture on growth and development, yield and quality of rice plant were studied systematically. The results are as follows:1. The effect of CWT during tillering stage was to reduce the panicles per hill and grains per panicle. CWT during panicle formation stage decreased the panicle length, branches and grains per panicle, filled grain rate and 1000-grain weight. CWT during 1-10days after heading stage enabled grains per panicle and 1000-grain weight to decrease. The effect of CWT on secondary branches, total grains on secondary branches, filled grain rate and 1000-grain weight was greater than that on primary branches. The sequence of yield reduction in two varieties under the same water stress condition was: treatments at panicle formation stage, treatment at tillering stage, treatment during 1-10days after heading, other treatments. The order of yield components affected by CWT was: panicle grains, filled grain rate, panicles per hill, 1000-grain weight.2. While SWP during tillering stage was kept at -30--35kPa, the heights of the two varieties were restrained obviously, but still were normal at last, the culms of the two varieties reduced apparently. While SWP during panicle formation stage were kept at -30--35kPa, the heights of the two varieties decreased obviously and its main reason was the internode length between the second node and the forth node decreased significantly. The culms of the two varieties were more than CK significantly. While SWP before heading stage was kept at -30--35kPa, the flag leaf area of the two varieties reduced apparently and depressed range at tillering stage was greater than that at panicle formation stage. CWT during tillering stage made areas of the second and the third leaf from top to reduce.3. While SWP was kept at -60--65kPa, grain-filling was affected distinctly, and grain-filling rate and Gmax.of many treatments decreased. R0 value of superior grain was the biggest, the second was middle grain, the last was inferior grain. Tmax··G value of inferior grain in two varieties was biggest, the second was middle grain, the last was superior grain. I value of many treatments after CWT decreased and D value increased.4. Brown rice rate and milled rice rate of most treatments by CWT before heading decreased differently. Many treatments of the two varieties by CWT after heading increased milling quality differently. The effect of CWT on head rice rate was greatest, the second was on milled rice rate, the last was on brown rice rate. While SWP was kept at -30--35kPa, the whole grain rate treated before heading, especially panicle formation stage decreased significantly. The immature grain rate increased significantly. Striped grain rate under CWT of differently-positioned grain was low and those of GAD at late stage and after heading stage were high. One of the main water sensitive stages that affected grain shape was panicle formation stage. Many treatments of the two varieties increased the grain thickness differently. Soil water affected grain length/ width of the two varieties slightly. Chalkness and percentage of chalk grain of all treatments, except tillering stage, in Shangyu 397 decreased differently and that of many treatments in Suijing 3 were reverse.5. While SWP during panicle formation stage was kept at -30--35kPa, protein content and fatty acid content in the two varieties increased significantly. Eating value of differently- positioned grain of treatments 3 and 4 in the two varieties decreased. Eating value under light CWT was higher than that of heavy CWT. Eating value of treatment 11, 12 did not decreased. Path coefficients between protein, amylose, fatty acid content and eating were as follows, Shangyu397 : p1>p2>p3 , Suijing3 : p1>p3>p2. The results showed that protein content had great influence on eating value in the two varieties. 6. While SWP was kept at -60--65kPa, albumin content increased under CWT before heading and albumin content decreased under CWT during 1-10day after heading. All treatments caused the glutelin and globulin contents to increase and eating quality to decrease obviously, except treatment 2. CWT had little influence on prolamin content. Albumin, globulin, glutelin contents of four kind of protein were different slightly. The effect of globulin on protein content and eating value was bigger than that of others. The ratio of glutelin to protein was first, the ratio of prolamin to protein was last, others were similar. Increasing albumin and globulin contents suitably, good eating trait of rice could be maintained.7. While SWP was kept at -30--35kPa, SOD activity in leaf of Shangyu397 under all treatments was lower than, or equal, that of CK, but Suijing3 was opposite. POD activity in the two varieties under all treatments was lower than that of CK fundamentally, the sensitive degree of POD to water stress was stronger than that of SOD. MDA content in leaf of the two varieties under all treatments increased,. CWT caused endopeptidase activity in leaf, protein content in grain and soluble sugar content in leaf to increase. The higher soluble sugar content in leaf was, the stronger ability of Q enzyme, or compose amylose, was, especially in superior grain.
|
PDF Full Text Request