紫云英还田下氮肥减施对桂南水稻光合特性及产量与品质的影响

Effects of Chinese milk vetch returning and reducing nitrogen fertilizer on rice photosynthetic characteristics, yield and quality in southern Guangxi

【目的】评价紫云英还田条件下化学氮(N)肥减施对水稻光合特性、产量及稻米品质的影响,探明水稻轮作紫云英的化学N肥替代潜力,为生产优质水稻提供科学依据。【方法】开展多年定位试验,设置常规施N(100%N)、紫云英还田配施100%、80%、60%和40%N肥(分别以MV+100%N、MV+80%N、MV+60%N和MV+40%N表示)及不施N肥(对照,CK)6个处理,在水稻抽穗期测定各处理的叶绿素含量(SP_(n)AD值)、净光合速率(P_(n))、气孔导度(G_(s))、胞间CO浓度(C)和蒸腾速率(T)等光合指标,在收获期考种测产并检测稻米的品质指标。【结果】与CK相比,紫云英还田配施100%、80%、60%和40%N肥均可显著提高水稻剑叶的SP_(n)AD值、P_(n)和G_(s)(P_(n)<0.05,下同),增幅分别为3.53%~7.29%、10.98~16.43%和4.88%~14.63%,并显著提高水稻产量及稻米蛋白含量,增幅分别为24.01%~41.85%和7.38%~18.17%。在光合特性方面,MV+100%N处理的SP_(n)AD值和P_(n)显著高于100%N处理,而MV+80%N处理和MV+60%N处理的SP_(n)AD值、P_(n)、G_(s)、C和T与100%N处理均无显著差异(P_(n)>0.05,下同);在水稻产量及性状方面,MV+100%N处理、MV+80%N处理和MV+60%N处理分别较100%N处理增产12.06%、7.72%和6.64%,但水稻产量及有效穗数、穗长、千粒重和结实率等与100%N处理均无显著差异;在稻米品质特征方面,MV+100%N、MV+80%N和MV+60%N处理稻米的加工品质、外观品质、营养品质与100%N处理均无显著差异,但MV+80%N和MV+60%N处理的稻米蒸煮品质显著高于100%N处理。相关分析结果表明,紫云英还田可通过提高水稻的SP_(n)AD值、P_(n)和G_(s)改善水稻产量性状,提高水稻产量,改善稻米的加工品质、蒸煮品质和营养品质。【结论】紫云英还田条件下配施100%、80%、60%和40%N肥均可显著提高水稻剑叶的SP_(n)AD值、P_(n)和G_(s)等光合指标和水稻产量,其中紫云英还田配施80%N肥或60%N肥对改善稻米加工品质、蒸煮品质和营养品质的效果均较佳,可在优质水稻生产中参考应用。

【Objective】The present paper aimed to evaluate the effects of reducing nitrogen fertilizer during Chinese milk vetch returning on photosynthetic characteristics, yield and quality of rice, to explore the potential of chemical nitrogen replacement in crop rotation of Chinese milk vetch and rice, so as to provide a scientific foundation for the production of high-quality rice.【Method】Based on years of positioning tests, a control group of no nitrogen fertilizer(CK) was used, and six treatments were set up, including conventional nitrogen application(100%N),Chinese milk vetch combined with 100%,80%,60% and 40% nitrogen application(marked as MV+100%N,MV+80%N,MV+60%N,MV+40%N) and no application of nitrogen fertilizer(control group, CK). Rice photosynthetic characteristics of chlorophyll content(SPAD value), net photosynthetic rate(P), stomatal conductance(G), intercellular COconcentration(C) and transpiration rate(T) were measured during the heading stage, and rice quality was measured during the harvest stage.【Result】In comparison to CK,a combination of 100%,80%,60% and 40% nitrogen fertilizer applied to returning Chinese milk vetch could significantly increase the SPAD value, P,and Gof rice(P<0.05,the same as below). The increases were 3.53%-7.29%,10.98%-16.43% and 4.88%-14.63%,respectively. Rice yield and protein content were also significantly increased by 24.01%-41.85% and 7.38%-18.17%,respectively. Compared with conventional N application(100%N),the SPAD value and Pof MV+100%N treatment were significantly higher than those of 100%N treatment. However, there were no significant differences in SPAD value, P, G, Cand Tin MV+80%N,MV+60%N and 100%N treatment(P>0.05,the same as below). In terms of rice yield and traits, yield of MV+100%N,MV+80%N and MV+60%N treatment increased by 12.06%,7.72% and 6.64% compared with 100%N treatment, but the yield, effective spikes, panicle length, number of grains per panicle, 1000-grain weight and seed setting rate had no significant difference with 100%N treatment. In terms of quality characteristics, there were no significant differences in milling quality, appearance quality, nutritional quality of MV+100%N,MV+80%N,MV+60%N and 100%N treatments. However, the cooking quality of MV+80%N and MV+60%N treatments were significantly improved compared with 100%N treatments. The results of correlation analysis showed that returning Chinese milk vetch could improve rice yield trait through increasing SPAD value, Pand G, thus, improving rice milling quality, cooking quality and nutrition quality.【Conclusion】Chinese milk vetch combined with 100%,80%,60% and 40% nitrogen application can significantly improve photosynthetic indexes and increase rice yield SPAD value, Pand G. Chinese milk vetch combined with 80% and 60% nitrogen application can also improve the milling quality, cooking quality and nutrition quality of rice, thus providing reference for high quality rice production.