| China is the biggest rice production country and it is also a country with severe shortage of water resources. The traditional cultivation method for rice production consumes huge amount of water and it alone uses nearly 65% of the total irrigation water in China. Therefore, the development and extension of water-saving rice cultivation technology is vital for saving the limited water resources and alleviating this problem of water shortage in China. This study was conducted in the experimental farm of Huazhong Agricultural University in 2007 and 2008. 4 varieties (combinations) of hybrid rice were used as experimental materials and planted on plots of paddy field. 2 treatments (half period dry management and traditional flooded cultivation as control) were adopted to provide the water. The half dry management maintained shallow standing water from transplanting till active tillering stage and discharged surface water at late tillering stage, and then kept the dry land management to maturity. comparetive analysis was made on the yield, main element analysis of quality, relative influence ratio and variance analysis. The effect of half period dry management on growth characteristics, yield and quality of rice and its water saving effect were investigated and discussed. The main results were as follows:1. It has saved 13.38 % of total water consumption in this experiment. if this study was in droughty year and in the condition of plenary using natural rainfall, maybe its potential of saving water would be larger. Production efficiency of grain and dry matter of treatment were 1.53 g. kg-1 and 2.81 g. kg-1, they were very significantly higher than traditional flooded cultivation about 35.4 % and 31.31 %. Thus it can be seen, half period dry management is capable of improving water using efficiency properly based on saving irrigation water.2. The growing stage of half period dry management delayed about 14 days compared with traditional flooded cultivation, plant height had no change, tillering stage of highest seedling peak was identical nearly. In addition, root biomass, root-shoot ratio was higher about 35.0 % and 25.0 % than contrast, difference reached very significant level. Besides that, SPAD and single stem wound flow was higher than contrast after growing stage, so it showed indirectly that half period dry management was propitious to maintain photosynthetic capacity and sustain root activity.3. The net increase of total biomass of half period dry management was 2.62 g and much higher than traditional flooded cultivation about 13.9 % during filling stage. Assimilates output rate of stem and sheath and total straw were 19.01 %,25.44 % and 19.87 %, which were higher about 9.3 %,13.9 % and 4.6 %, but difference did not reached significant level. Therefore, half period dry management promoted assimilate transportation and distribution in stems and straw, it was benefical to the formation of grain yield.4. Grain number per panicle and yield increased about 1.7 % and 5.2 % for most of varieties in comparison with traditional flooded cultivation. Positive correlations (r=0.8570**, 0.8094**, respectively) were found between seed setting rate, spike number and yield. The size relation of yield conponents as fellows: seed setting rate>spike number>ear length>1000-grain weight>grain number per panicle, seed setting rate and spike number were restriction factors of yield components.5. The mean head milled rice rate and Length/wide and protein content somewhat increased under half period dry management, the increase were 19.95 %,0.49 % and 0.27 % respectively; but brown rice rate and chalk percentage and chalkiness was reduced, the increase were 1.34 %,12.36 % and 14.95 % respectively. That was to say which could improve partial quality.6. About the different ratios of cutting lateral root under half period dry management and traditional flooded cultivation, the results showed that, cutting root all lead to the decrease of grain, the decreasing range interval of contrast was 6.25 %-32.03 %, but the treatment was 11.36 %-50.76 %, thus, cutting lateral root had more remarkable effect on grain under half period dry management and its root was not redundant growth. |
