不同还原物料及土壤改良剂对冬水田水稻生长、养分吸收和土壤性状的影响

Impacts of reducing materials and amendments on rice yield,nutrient uptake and soil properties in the waterlogged paddy field

为探究水稻在土壤淹水还原性条件下坐蔸成因以及防治措施,通过盆栽试验添加不同还原物料,对比分析两个抗性不同的水稻品种在土壤还原性条件下生长反应。采用盆栽试验,模拟冬水田长期渍水状况,研究了3种还原物料(稻草粉、硫酸亚铁和白糖)不同用量和4种潜在改良剂对两个水稻品种(川香优9838和川谷优7329)生长的影响。试验设12个处理,每个处理5次重复。结果表明,稻草粉20 g·kg-1和白糖5 g·kg-1处理对两个水稻品种的分蘖动态影响最大,这两个处理对川香优9838有效穗分别比对照下降40%和25%,对川谷优7329均下降45. 8%。低量的稻草对水稻生长有一定促进和增产作用,随着稻草用量增加,水稻生长受到抑制,产量降低; 20 g·kg-1稻草粉处理降低了川香优9838和川谷优7329产量,降幅分别达19. 7%和46. 1%。与对照相比,硫酸亚铁比过量施用稻草处理显著增加了川香优9838的产量;所有其他处理均较稻草粉20 g·kg-1处理增加或显著增加了水稻产量。稻草粉处理显著增加了土壤Fe2+和Mn2+含量,降低了Eh值,并与稻草粉用量呈正相关;而白糖、硫酸亚铁处理对土壤Fe2+、Mn2+和Eh影响不显著。在稻草粉20 g·kg-1处理基础上施用不同土壤改良剂,石灰和硼砂对水稻苗期毒害有缓解作用,但效果并不明显。四川省冬水田前季水稻收获时局部残留稻草堆积是翌年水稻坐蔸发生的主要原因,稻草在分解过程中产生的还原性有毒物质抑制了水稻生长,从而造成水稻减产;在冬水田稻区,少量稻草还田能促进水稻生长,比其他大多数处理显著增加水稻产量。

In order to explore the causes and counter-measures for straighthead disease of paddy rice grown under waterlogged conditions,a pot experiment was carried out to study the effects of addition of different reducing materials on growth of two rice cuhivars varying in their resistance to the disease.The experiment consisted of twelve treatments including three reducing materials (rice straw,ferrous sulfate and sugar)and four potential amendments with five replications.Two rice cultivars (Chuanxiangyou 9838and Chuanguyou 7329)were employed and grown under waterlogged conditions throughout the growing season. It showed that the two treatments,20g ·kg^-1 rice straw and 5g·kg^-1 sugar,strongly impacted tillering of the two rice culfivars.Effective tillers of Chuanxiangyou 9838were reduced by 40%and 25%by the two treatments,respectively,and those of Chuangnyou 7329were equally reduced by 45.8%compared to the control.Rice grain yield increased firstly with an in- crease in rates of straw added and then decreased,and thus,the treatment with 20g·kg^-1 rice straw produced the lowest flee yield,19.7%and 46.1%lower for Chuanxiangyou 9838and Chuanguyou 7329,respectively,than that with the control. Addition of ferrous sulfate,however,produced the higher rice yield than the control for Chuanxiangyou 9838,and all the other treatments achieved much higher rice yield than the straw 20treatment.Rice straw treatments significantly enhanced contents of Fe^2+and Mn^2+and decreased Eh values of the soil,which were well correlated with rates of rice straw added;while the treatments of sugar and ferrous sulfate non-significantly impacted contents of Fe^2+,Mn^2+and Eh values.Among the four treatments with addition of different amendments on the basis of rice straw,only lime and sodium borate alleviated straighthead disease to some extent at rice seedling stage.The piled-up rice straw in the all-time waterlogged paddy field from previous harvest could be the main reason for the straighthead disease of next rice season.The released toxic reducing substances from the residual rice straw decomposition,thus,impeded plant growth and finally resulted in rice yield reduction.In the all-time waterlogged paddy rice region,application of reasonable rate of rice straw can promote flee growth and significantly increase rice yield as compared to most of the treatments.