强筋与弱筋小麦籽粒蛋白质组分与加工品质对灌浆期弱光的响应

选用强筋小麦品种济麦20和弱筋小麦品种山农1391,在大田试验条件下,分别于籽粒灌浆前期(花后6—9 d)、中期(花后16—19 d)和后期(花后26—29 d)对小麦进行弱光照处理,研究了籽粒产量、蛋白质组分及加工品质的变化。灌浆期弱光显著降低小麦籽粒产量,灌浆中期对济麦20和灌浆后期对山农1391的产量降幅最大。弱光处理后,籽粒氮素积累量及氮素收获指数减少。但弱光使籽粒蛋白质含量显著升高,其中灌浆中期弱光升幅最大,原因可能是由于其粒重降低造成的。弱光对可溶性谷蛋白无显著影响,但增加不溶性谷蛋白含量,使谷蛋白聚合指数显著升高,面团形成时间和稳定时间亦升高,籽粒灌浆中、后期弱光对上述指标的影响较前期大。灌浆期短暂的弱光照对改善强筋小麦粉质仪参数有利,但使弱筋小麦变劣;并均伴随籽粒产量的显著降低这一不利影响。

Comparison of grain protein components and processing quality in responses to dim light during grain filling between strong and weak gluten wheat cultivars

Low light intensity as a result of cloudy or rainy days often occurs during the grain filling of winter wheat (Triticum aestivum L.) in Huanghuai region of China, largely affecting grain yield and quality. Many investigators have demonstrated the effects of shading on photosynthesis, dry matter accumulation, grain yield and its components of winter wheat. However, there are few reports on the effects of shading on protein compositions and processing quality in wheat grain. The strong gluten wheat cultivars are remarkably different from the weak gluten cultivars in many grain quality parameters. This study attempted to determine the processing quality and protein compositions of wheat cultivars differing in quality type wheat grown under low light intensity at different grain filling stages. Two wheat cultivars, Jimai 20 (strong gluten wheat cultivars) and Shannong 1391 (weak gluten wheat cultivars), were used to investigate the effect of dim light on grain yield, protein compositions and processing quality. The field was shaded by the black nets with 90% shading over the plants in early (6-9 d after anthesis, S1 treatment), middle (16-19 d after anthesis, S2 treatment) and late (26-29 d after anthesis, S3 treatment) grain filling. The treatments were arranged in a randomized complete design with three replications. The results showed that dim light after anthesis remarkably reduced grain yield, especially in S2 treatment for Jimai 20 and S3 treatment for Shannong 1391. Shading stress after anthesis significantly decreased the kernel weight. The kernel number per spike had great difference in treatments. The low light stress of S1 treatment reduced the kernel number per spike, in fact, it reduced the upper kernel number per spike, and the decrease extent of kernel weight of S1 treatment was lower than S2 and S3 treatments. Under shading condition, grain nitrogen accumulation and nitrogen harvest index decreased sharply in both cultivars. Dim light after anthesis significantly increased the grain protein content in both cultivars, especially at the middle grain filling stage, and the trend as following: S2>S3>S1>Control. Combined grain protein content with kernel weight, we suggested that it was less kernel weight that increased protein content of shading treatments. Under shading stress, especially at middle and late grain filling stages, the insoluble glutenin content enhanced significantly, but the soluble glutenin content was no significant difference with the control, then, the glutenin polymerization index in grain increased sharply. Compared with the control, The dry and wet gluten contents and sedimentation values were all significantly increased at three shading stress. And dim light after anthesis significantly increased the dough development time and stability time, especially at middle and late grain filling stages. After it was analyzed that the relationship between the farinograph parameters and insoluble glutenin content and glutenin polymerization index of two wheat cultivars. The results suggested that different farinograph parameters were tied up by the differences of insoluble glutenin contents and glutenin polymerization indexes between the cultivars. Insoluble glutenin contents and glutenin polymerization indexes affected farinograph parameters, and then influenced wheat grain processing quality.. Transient shading stress during grain filling improved farinograph parameters for strong gluten wheat cultivars, but worsen farinograph parameters for weak gluten wheat cultivars. And grain yield decreased significantly at one time.