The Research On The Physiological Mechanism Of Premature Aging In Spring Wheat Caused By High Temperature In Different Periods After Anthesis

Global climate change causes the extreme weather, such as the high temperature frequently accurring. It leads to premature aging, declining production in spring wheat, which is the main reason for seriously restricting the production of spring wheat. So two spring wheat varieties (NingChun4and NingChun47) as materials were used to study the physiological mechanism of premature aging caused by high temperature in different periods after anthesis. The main results were as followed:1、High temperature after anthesis promoted premature aging in spring wheat, resulting in decrease in chlorophyll content, decline in photosynthetic rate and fluorescent comprehensive value of PI. In addition, the earlier of high temperature period, the greater of impact on photosynthesis and the more serious the premature aging. This study found after5days of anthesis the treatment of high temperature to premature aging of spring wheat was the greatest impact. It caused net photosynthetic rate of T2D1in NingChun47and NingChun4reduced than TI (CK) by25.37%and34.35%after15days of flowering; Fluorescence comprehensive value PI decreased in12.81%and12.81%, respectively; Chlorophyll content (SPAD value) decreased in34.11%and34.11%respectively.2、High temperature after anthesis significantly decreased the activity of protective enzyme, permeability of cell membrane increased, MDA content increased, membranous peroxide degree increase. Heat treatment the earlier, the greater the wheat body hurts, the more rapidly the protective enzyme activity.The T2D1of15d from NingChun4and NingChun47after anthesis of membrane permeability increased by25.78%and25.78%respectively;The contents of MDA increased by94.28%and19.38%; The content of POD increased by16.44%and11.48%respectively; The contents of SOD increased by44.18%, NingChun47was reduced by30.16%; The CAT content of NingChun No.4increased by21.61%and NingChun No.47reduced by15.91%; The content of Proline NingChun No.4increased by43.83%, and NingChun No.47was reduced by4.8%.3、High temperature treatment reduced the yield of spring wheat significantly, promote plant premature aging, and the earlier high temperature treatmentthe the greater impact on yield, The more severe premature aging plants, decrease of grain starch content, starch synthase is reduced, dry matter accumulation and plant senescence in advance, for these reasons lead to the grouting is insufficient, grain weight and yield decreased.High temperature treatment after anthesis the NingChun4of T2D1, T2D2, T2D3, T2D4, T2D5to compare with T1(CK) of thousand seed weight was reduced by52.18%,39.62%,36.74%,42.06%and36.04%; Economic coefficient was reduced by54.17%,27.08%,54.17%,31.25%,and22.92%. High temperature treatment after anthesis the NingChun47of T2D1, T2D2, T2D3, T2D4, T2D5compare with T1(CK) of thousand seed weight was reduced by37.54%,27.78%,17.4%,23.17%and9.56%; Economic coefficient was reduced by20.57%,14.45%,20.57%,2.57%and2.53%.4、It indicated that the Correlation analysis and principal component analysis of high temperature on spring wheat physiological, the biochemical related indicators the yield and photosynthetic rate, fluorescence parameters PI, chlorophyll content, and other protective enzyme activity was positively correlated; with MDA, leaf membrane permeability, proline, etc. There was a negative correlation. Principal component analysis showed that the protective enzyme factor on yield and photosynthetic factors contributed greatly. Therefore, increasing the protection of high activity, accelerate the rate of photosynthesis, photosynthetic rate to extend the duration of the high value, increasing the Fv/Fm, PI, chlorophyll content, is conducive to the accumulation of spring wheat starch content and yield increase.