| Irrigation water management is becoming critically important throughout the world. China has led to the urgent need in reduction of irrigation. Rice is the important food crop and consumes the greatest irrigation water in China as well as Zhejiang. As freshwater for agriculture becomes increasingly scarce, the measure should be taken to improve the water utilization efficiency in rice production. Presently, the water-saving and high-efficiency rice cultivation (WSHERC) mainly involved in direct-seeded rice with moist cultivation (DS), transplanted rice with moist cultivation (TP) and dry cultivation with mulched plastic film (DC). The field experiments for two consecutive years (1999 and 2000) with above three WSHERC were conducted to determine their ecological effects on rice field, especially in soil water content and temperature, and on nutrient accumulation, distribution and translocation, and dry matter accumulation as well as grain filling rate. In addition, the effect of DC, DS and TP on root and leaf senescence, photosynthesis during the grain filling stage and grain yield and quality were also studied. DC included dry-direct-seeding and wet-direct-seeding. There were three methods of WSHERC with moist cultivation (WMC): dry-direct-seeding, wet-direct-seeding method and transplanting, and corresponding controls are their conventional cultivation methods (CK). The main results were as follows: 1) All WSHERC have obvious functions in terms of water saving, thus leading to reduced irrigation times and irrigation water consumption, and increased water use efficiency (WUE). Soil water content (SWC), on an average of whole rice growth duration, varied in treatments and was 30%, 35~39% and 40?45% for DC, WMC and CK, respectively. In the field treated by WSHERC, the temperature at the ground surface. 5cm and 10cm depth. underground, daily maximum i.emperature and daily? temperature difference were higher than those in the control. The daily minimum temperature in WMC was lower than that in the control, but it was higher for DC. In comparison with moist cultivation, daily surface and underground temperature in DC condition showed significant increase. In addition, the time of daily maximum temperature occurred later as the ground depth increased. The results showed that DC significantly increased the surface and underground temperature. As a result, WSHERC might be favorable to higher rate in soil nutrient release and absorption by Iv rice due to its regulation of the soil moisture. 2) The variation in shoot dry matter accumulation during the duration from booting to maturity stage revealed that the total dry matter under DC was lower than that in moist cultivation, and became greater with the growth and development. In comparison with CK, the total shoot dry matter in WMC was lower before booting stage, similar at heading, and higher during grain filling stage. As to the redistribution of dry matter to various plant organs, there were no insignificant difference at booting stage among the treatments, but relatively less and more allotment to ear and to leaf blade, respectively were found for DC at heading stage. Moreover, at maturity stage, DC had highest ratio of dry matter allotment in ear followed by WMC and CK was leaf sheath the lowest. Correspondingly, allotment ratio of dry matter in ~ was lower for both DC and WMC. The translocation of the biomass after... |
PDF Full Text Request