Studies On Relationship Of Endogenous Hormones To Grain Development And Filling In Wheat

~: 慗拁-~~~ STUDIES ON RELATIONSHIP OF ENDOGENOUS HORMONES TO GRAIN DEVELOPMENT ANII) FILLING IN WHEAT Postgraduate: Sheng Jing Supervisor: Prof Feng Chaon Ian & Prof Guo Wenshan &Prof Peng Yongxin (Agric. Coil., Yangzhou University, Yangzhou 225009) ABSTRACT The relationship of endogenous hormones to grain development and filling was analysed, dynamic changes in endogenous hormone content and their proportions and physiological mechanism were studied in wheat (Triticum aestivum L.) on the Experimental Field of Crop Cultivation and Physiology Key Laboratory, Yangzhou University from 1998 to 2000. The major results could be concluded as follows: 1. The dynamic changes of endogenous hormone content in wheat During spike differentiation, GA content in young ear was increased from elongation to floret primordium formation, then declined sharply, and changed relatively steadily from pistil and stamen primordiuxn formation to booting stage. Change of GA content in flag leaves and grains was showed as a characteristic curve with a single peak: GA content in flag leaves changed relatively steadily from booting to anthesis, then increased sharply and reached peak value at the 7th day past anthesis(DPA) and then began to decline. GA content in grains for different treatments had the similar change tendency, but the peak time appeared at the 21St DPA for optimal sowing treatment, and at the 14th DPA for late sowing treatment. IPA and ZR content in young ear was relatively low from single-ridge to floret 40 primordium formation, then increased sharply and reached peak value at pistil and stamen primordiuni formation and then began to decline. WA and ZR content in flag leaves increased till the 7th DPA to reach the maximum value, and declined quickly from the 7th DPA to the 21st DPA, and then changed relatively steadily. ZR and WA content m grain declined continuously the 7th DPA after. The change of ABA content in the young ear was high at elongation, and low at single-ridge, then increased steadily and reached peak value at booting stage. ABA content in flag leaves was increased continuously till anthesis and declined quickly from anthesis to mature. Dynamic change of ABA content in grains was resembled to that in flag leaves. IAA content in young ear was relatively low in the early stage of spike differentiation, and rise rapidly from floret primordium formation to pistil and stamen primordiuni, then declined sharply. IAA content in grain reached the peak at the 14th DPA, then declined. 2. Relationship between hormone and grain development and filling (1 )Relationship between endogenous hormone and leaf growth GA, WA and ZR content had no difference in different functional leaves of the same period. But there existed significant difference in ABA content. ABA could delay leaf senescence in early stage. At elongation, ABA content of the top 2 leaf was higher than that of the top 3 leaf. From late double-ridge to booting ABA content was the top 4 leaf> the top 3 leaf> the top 2 leaf> the top 1 leaf. Increase of ABA content was synchronized with leaf senescence. (2)Relationship betw...