油菜秸秆还田对水稻根系分布及稻谷产量的影响

根系健康是水稻正常生长及高产的前提,为明确油菜秸秆还田方式和还田量对水稻生长及产量的影响,以秸秆不还田作为对照,设置秸秆半量还田(1.5 t/hm²)、全量还田(3.0 t/hm²)、超量还田(4.5 t/hm²)3个还田量以及秸秆覆盖还田(FG)、秸秆翻埋还田(FM)两种还田方式,通过盆栽和大田试验相结合,研究秸秆处理对水稻根系分布及产量构成的影响.结果显示,秸秆快速腐解期(移栽后第23天)根系总长度、总鲜重及白根长度、白根鲜重均随还田量的增加而减少,但缓慢腐解期(移栽后第53天)覆盖处理总根系变化趋势与前期一致,翻埋处理根系长度和鲜重在FM2、FM3处理较大.覆盖还田促进移栽后期20-50 cm土壤中根系的生长,翻埋还田促进移栽后期各土壤深层根系的生长.覆盖和翻埋还田在返青期分蘖数分别比秸秆不还田减少1个/株和1.67个/株,翻埋还田更不利于返青期分蘖保持,但翻埋处理在移栽后期更有利于分蘖数的增加.单株有效穗在超量还田处理下达到最大值12.11和12.65,但千粒重、结实率、穗着粒数和产量均在全量还田处理下达到最高水平.本研究表明油菜秸秆还田抑制水稻移栽前期根系生长,同时覆盖处理对移栽后期根系生长不利,翻埋处理明显促进移栽后期根系的生长;油菜秸秆还田处理能提高水稻产量,其中以秸秆全量还田效果最佳.(图6表4参38)

Effects of rape straw returning on root distribution and yield of rice

The objective of this research was to illustrate the effects of oilseed-rape straw returning on the growth and yield of rice, as a healthy root system is required for the growth and high yield of rice. Two straw returning methods, mulching(FG) and burying(FM), and four returning amounts(0, 1.5, 3.0, and 4.5 t/hm²) of rape straw were used for this experiment. The effects of rape straw returning on the root distribution and yield components of rice were studied using pot and field experiments. Results indicated that the length and fresh weight of total roots, as well as the length and fresh weight of white roots, all decreased with increasing amounts of straw returning during the rapid straw decomposition period(23 d after transplanting). However, the dynamic changes in total roots under the FG treatment were consistent during the early stage and the slow decomposing period(53 d after transplanting), and the root length and fresh weight of FM2 and FM3 during the slow decomposing period were greater than those during the early stage. Straw returning by FG promoted the growth of rice roots in 20-50 cm soil, while straw returning by FM was better for the growth of roots in all observed soil layers during the slow decomposing period associated with rape straw. During the regreening stage of rice, the tiller number of rice under FG and FM treatments decreased by 1 and 1.67 per plant, respectively, compared with the control treatment. Compared with the FG treatment, the FM treatment was more detrimental to tiller maintenance in the regreening period, but it was found to better for increasing the tiller number in the later period of transplanting. The number of panicles per plant reached a maximum value of 12.11 and 12.65 with excess of straw returning, but the 1 000-grain weight, spikelet fertility, spikelet per panicle, and yield all reached the highest level with the full amount of straw returning. This study showed that returning rape straw into the field hindered root growth during the early stage of rice growth. Straw returned by FG was a disadvantage to root growth, while straw returned by FM promoted root growth during later stages of rice growth. Returning rape straw into the field, either by FG or by FM, increased the grain yield of rice. In addition, rape straw returning methods based on high quantities(the full amount in the present study) may be beneficial for rice production.