Studies On Root Developmental Characteristics And Their Correlations With Grain Yield And Quality In Strong-Gluten Wheat (Triticum Aestivum L.)

【Objective】In this paper,different nitrogen application levels, chemical regulators,and strong-gluten wheat genotypes were employed to form wide differences in root morphology and physiology.Under different conditions, morphological and physiological traits of strong-gluten wheat root system and their correlations with grain yield and quality were systimatically studied in order to provide a theoretical basis for the high yield and quality.【Materials & Methods】High,medium,and low nitrogen application rates,two chemical regulators of ABT and NAA,and strong-gluten wheat cultivars Yumai 34, Zhengmai 9023,and Shanyou 225-19 were used in these field experiments. Morphological and quantitative root traits such as nodal roots per plant and per culm, root vigor,H~+-ATPase activity in roots,contents of total soluble sugars and total nitrogen were determined at different developmental stages before overwintering, regreening,jointing,flag leaf,grain formation,middle grain filling,and dough.Grain yield was determined and its commponents analysed when harvest,and in laboratory contents of grain protein,starch,wet gluten and flour paste traits were also analysed.【Results】The main results were as belows:(1)Morphological and quantitative root characteristics in strong-gluten wheat genotypes Changes of nodal roots per plant and per culm of strong-gluten wheat cultivars at different developmental stages were just like those of cultivars with common quality.They increased at first and decreased gradually then as the plant developed.(2)Physiological root characteristics in strong-gluten wheat genotypes Content of total soluble sugars in roots of strong-gluten wheat cultivars decreased at overwintering,but gradually increased after jointing and reached the maximum at flag leaf stage,and then gradually decreased.Total nitrogen content in roots was high at early and late developmental stages,but was low during middle stages.It gradually increased from overwintering to regreening stage,and then decreased until grain formation stage.Root vigor gradually decreased at overwintering stage,increased after regreening stage and got the maximum at jointing stage,and then showed a decreasing trend until dough stage.H~+-ATPase activity in roots was low at early stages,high at middle stages,and gradually decreased at late stages,showing a M-like curve.(3)Correlations of wheat root traits with grain yield and quality in strong-gluten wheat genotypes①Negative correlations existed between nodal roots per plant and root vigor and grain yield and quality at early stages,but some positive correlations appeared later,especially at grain formation and grain filling stages.②Nodal roots per plant and per culm of strong-gluten wheat cultivars had correlations with protein content in grains.Correlation between nodal roots per culm and grain protein content was significant(5%level)at dough stage,but at other every stages,correlations of nodal roots per plant and per culm of strong-gluten wheat cultivars with protein content in grains were either positive or negative.Positive correlations between total nitrogen content in roots and protein content in grains were extremely significant(1% level)at grain formation stage.Ccorrelation between root vigor and protein content in grains was extremely significant at regreening and grain formation stage.Correlation between H~+-ATPase activity in roots and protein content in grains was positive. Correlation between total soluble sugar content and protein content in grains was significantly positive at overwintering stage,but significantly or extremely significantly negative from flag leaf to grain formation.③Significantly positive correlations between nodal roots per plant and per culm of strong-gluten wheat cultivars and wet gluten content at overwintering and jointing stage,but at other stages,either positive or negative correlations presented.Total nitrogen content in roots and wet gluten content had a close correlation which was significant or extremely significant at almost every stages.Positive correlations existed between total soluble sugar content and wet gluten content at early stages while negative correlations existed at late stages.Certain correlations were between H~+-ATPase activity in roots and wet gluten content.④Significantly or extremely significantly positive correlations existed between nodal roots per plant and per culm of strong-gluten wheat cultivars and peak viscosity at early stages,but at other stages the correlations were either positive or negative.Correlations between H~+-ATPase activity and total nitrogen content in roots and peak viscosity content were not significant at each stages.A positive correlation existed between total soluble sugar content and root vigor and peak viscosity especially at regreening stage.(4)Regulation and control on development of root system in strong-gluten wheat genotypes①All nitrogen application rates,chemical regulators,and strong-gluten wheat genotypes had significant effects on nodal roots per plant and per culm.②Nitrogen application enhanced root vigor,and chemical regulators had also helped either improve or retard root vigor.③Total nitrogen content in roots incresed with nitrogen application rate.ABT had restricting effects on total nitrogen content in roots while NAA had promoting effects.Total nitrogen content in roots of strong-gluten genotypes differed at different stages.④Total soluble sugar content in roots decreased with nitrogen application.ABT had promoting effects on total soluble sugar content,but NAA had restricting effects.【Conclusions】Correlationships does exist between root development and grain yield and quality in strong-gluten wheat cultivars.In production practice,it is recommended that reasonable cultivation techniques regulating the development of root system be used to increase grain yield and improve grain quality.