臭氧浓度增加对超级稻南粳9108稻穗不同部位籽粒氨基酸含量的影响

为了解臭氧浓度升高对稻米品质的影响,2015年以高产优质超级粳稻南粳9108为供试材料,利用自然光气体熏蒸平台,设置对照(18 n L·L~(-1))和高浓度臭氧(100 n L·L~(-1))处理,研究了臭氧浓度增加对成熟期稻穗不同部位糙米氨基酸性质的影响。结果表明:臭氧浓度增加使稻米氨基酸、必需和非必需氨基酸总量显著增加,但对必需或非必需氨基酸占氨基酸总量的百分比无显著影响;从氨基酸组分看,除半胱氨酸外,臭氧浓度增加使糙米中7种必需氨基酸和9种非必需氨基酸的含量均呈增加趋势,其中苏氨酸、丝氨酸、谷氨酸、亮氨酸、络氨酸、天冬氨酸和苯丙氨酸的增幅均达显著或极显著水平;总体上,稻穗下部稻米氨基酸及其组分浓度对臭氧浓度增加的响应大于稻穗上、中部,其中臭氧处理与籽粒着生部位对苯丙氨酸、络氨酸、组氨酸、精氨酸有明显的互作效应(P0.1)。以上数据表明,100 n L·L~(-1)臭氧浓度使供试超级稻稻米氨基酸及其组分浓度明显增加,且多数情况下弱势粒的增加趋势大于强势粒。

Impacts of ozone stress on grain amino acids of super rice cultivar Nanjing 9108 differ with grain positions on a panicle

The increase of ground-level ozone concentration caused by human activities can reduce rice yield, but its effects on rice quality, especially super rice quality in association with grain positions in panicles were not studied yet. A Japonica super rice NJ9108 was grown in glasshouse type chambers at either low(18 nL·L^-1) or high(100 nL·L^-1) ozone concentration from seedling transplanting until plant maturity. The seeds on a panicle were separated into three groups based on its position on a panicle, namely upper, middle and lower part of a panicle. The grains from the upper and lower part of the panicle refer to superior and inferior grains, respectively. Compared with plants grown in clean air with low ozone concentrations, ozone stress significantly increased the contents of total amino acids, essential amino acids and nonessential amino acids, but the percentage of essential or nonessential amino acids to total amino acids was unchanged. Except for cysteine, ozone stress induced a trend of increase in the concentrations of other 16 amino acids, among which the significant increases were detected for threonine, serine, glutamic acid, leucine, tyrosine, aspartate and phenylalanine. In general, ozone stress had greater impacts on amino acid concentrations of inferior grains than the superior grains or the grains in the middle part of a panicle, and ozone by grain position interactions were significant at P<0.1 for concentrations of phenylalanine, tyrosine, histidine, arginine. The results indicated that ozone concentration of 100 nL·L^-1 during the growth of super rice increased total amino acids and its components, and in most cases, the increase of amino acids concentration in inferior grains is greater than superior grains.