结实期土壤水势对水稻籽粒品质及其粒间差异的影响

Effect of soil water potential on grain quality at different spike positions during grain filling in rice

为探讨结实期土壤水分对水稻籽粒品质的影响,以中熟籼稻"扬稻6号"和中熟粳稻"扬粳9538"为材料,在盆栽条件下,研究了不同土壤水势(0 kPa、–15 kPa、–30 kPa、–45 kPa)对水稻籽粒品质的影响,并进一步探讨了不同粒位间的差异。结果表明,结实期土壤水分对稻米籽粒品质有较大影响,且影响程度因品种、粒位不同而异。与对照(0 kPa)相比,土壤轻度胁迫(土壤水势在-15～-30 kPa之间)籽粒的精米率、整精米率和崩解值增加,垩白度和消碱值降低;不同粒位间比较,土壤轻度胁迫对水稻穗上二次枝梗或同一枝梗上较迟开花籽粒的影响较大。随土壤水势进一步降低稻米品质变劣。在0～–45 kPa范围内,随土壤水势的降低,粗蛋白含量和胶稠度增加。灌浆期土壤轻度落干(土壤水势在-15～-30 kPa)有利于稻米品质的改善。

This study investigated the effects of soil moisture stress during grain filling on the quality of grains at different rice spike positions.Two rice cultivars,＂Yangdao 6＂（indica） and ＂Yangjing 9538＂（japonica）,were pot-grown and subjected to four soil moisture treatments（0 kPa,–15 kPa,–30 kPa,–45 kPa） during post-anthesis grain filling stage.The study showed that soil moisture condition during the grain filling greatly influenced grain quality.The sensitivity of grain quality to soil moisture varied with cultivar and grain position within the panicle.Compared with 0 kPa（CK） soil water potential,milled rice rate,head milled rice rate and breakdown value at an increased rate under moderate dry soil treatment（i.e.,soil water potential of –15～ –30 kPa）.However,the degree of chalkiness and setback value decreased.Grains from secondary branches were more obviously affected than those from primary branches.Furthermore,moisture stress had greater effect on grains that flowered late than those that flowered early in the same branch.Rice quality also worsened with decreasing soil water potential.As soil water potential dropped from 0 kPa to –45 kPa,crude protein content and gel consistency increased.The results suggested that moderate dry soils with water potential of -15 ～ -30 kPa at grain filling enhanced grain formation and rice quality.