外源海藻糖对高温胁迫下穗分化期水稻叶片生理特性及产量的影响

该研究以耐热型水稻品种Nagina22和热敏型水稻品种YR343为供试材料,采用盆栽试验,设置喷施清水+常温处理(NT0)、喷施清水+穗分化期高温胁迫(HT0),以及分别喷施5、10、15、20 mmol·L^-1外源海藻糖+高温胁迫(分别记为HT1、HT2、HT3、HT4)共6个处理,分析外源海藻糖对高温胁迫下穗分化期水稻叶片叶绿素含量、光合气体交换参数、抗氧化酶活性、渗透调节物质含量、活性氧含量等生理特性,以及籽粒产量及其构成因素的影响,为水稻抗热栽培和耐热品种的选育提供理论依据。结果表明:(1)在高温胁迫下水稻穗分化期,2个水稻品种叶片的叶绿素含量、光合气体交换参数及渗透调节物质含量均降低,叶片MDA和H₂O₂含量以及■的产生速率均上升,叶片抗氧化酶活性呈先增后降的趋势,最终显示水稻籽粒产量及其构成因素显著下降。(2)喷施外源海藻糖能显著增加高温胁迫下穗分化期水稻的每穗粒数、千粒重和结实率,从而提高籽粒产量,其中弱势粒千粒重和结实率的增幅高于强势粒,外源海藻糖最适喷施浓度为15 mmol·L^-1...

Effects of Exogenous Trehalose on Leaf Physiological Characteristics and Yield of Rice at Panicle Initiation Stage under High Temperature Stress

In this study, Nagina22 (a heat-resistant rice variety) and YR343 (a heat-sensitive rice variety) were selected as test varieties. Six treatments were set: spray water + normal temperature treatment (NT0), spray water + high temperature stress at panicle initiation stage (HT0), and spray exogenous trehalose + high temperature stress (HT1, HT2, HT3, HT4) at 5, 10, 15, 20 mmol·L^-1, respectively. The effects of exogenous trehalose on chlorophyll content, photosynthetic gas-exchange parameters, antioxidant enzyme activities, osmotic regulatory substance content, active oxygen content and yield of rice during panicle initiation stage under high temperature stress, were analyzed to provide theoretical basis for developing heat-resistant rice cultivation and breeding heat-resistant varieties. The results show that: (1) under high temperature stress at panicle initiation stage, the contents of chlorophyll, photosynthetic gas exchange parameters and osmotic regulatory substances in the leaves of the two rice varieties decreased, while the contents of MDA and H₂O₂ in the leaves, as well as the production rate of O₂^-· increased, and the activities of antioxidant enzymes in the leaves increased first and then decreased; which resulted in a significant decline in the kernels yield and its constituent factors. (2) Application of exogenous trehalose could significantly increase the number of grains per panicles, 1000-grain weight and seed setting rate of rice at panicle initiation stage under high temperature stress, thus improving yield. The 1000-grain weight and seed setting rate of the inferior spikelets were higher than that of the superior spikelets. The optimal concentration of exogenous trehalose was 15 mmol·L^-1. (3) Exogenous trehalose spray with appropriate concentration can improve the chlorophyll content of rice leaves, promote the photosynthetic rate, enhance the activities of antioxidant enzymes SOD, POD and CAT, increase the contents of soluble sugar and soluble protein, and reduce the contents of MDA, H₂O₂ and the production rate of O₂^-·, so as to alleviate the damage to rice caused by high temperature stress at panicle initiation stage and improve the yield. It was found that exogenous application of 15 mmol·L^-1 trehalose could improve the photosynthetic physiological characteristics of rice leaves, enhance osmotic regulation ability, enhance the activity of antioxidant enzyme system, and thus improve the heat resistance and grain yield of rice under high temperature stress at the panicle initiation stage. The results can provide a theoretical basis for developing heat-resistant cultivation and breeding of heat-resistant rice varieties.