Effects Of Different Weak Light Duration At Anthesis Stage On Physiology Characteristics And Grain Yield Of Maize

The aim of this study was conducted from 2015-2016 year and 6-9 month in the experimental farm of Henan Meteorological Station,selects the main summer maize varieties of huanghuaihai plain deepened 29 for single material,use 70% light transmittance of shade net,from the most sensitive response to weak light processing period(tasseling stage)began to set different shade processing time length,explore the corn flowering duration of weak light effects on grain yield and physiological characteristics.Its main findings are as follows:1.As the time of the low light processing of the corn is increased,the pollen shedding ending dates and silking date delay time are extended with the accompany low light stress duration elongation since tasseling,of which silking date delay time longher than the pollen shedding ending dates delay time,the husk length rate was smaller with the fast growing period extended,but maintained high growth rate at 12 d after tasseling,leading to husk length increased no significantly,dry matter accumulation rate decreased significantly,as well as the naked ear length,dry matter weight and filaments elongation rate,These decreases infulenced the ear at the top of the filaments remarkablely,extening the powder interval,reducing the number of spinning,pollination fertilization and seed setting rate.2.Flowering duration of weak light stress had significant effect on photosynthetic physiological characteristics of maize.There were no significant effect of weak light stress during 3 d on chlorophyll(chlorophyll A and chlorophyll B,chlorophyll and carotenoid(A + B))and 2000 mu in mol · m-2 · s-1 under the condition of photosynthetic rate of ear leaf(P2000),stomatal conductance(P2000)(Cond2000)and intercellular CO2 concentration(Ci2000).Weak light processing more than 6 days of chlorophyll content and the comparison between the difference reached significant level,P2000 at weak light duration of 6-9d and over 12 d treatment decreased slightly;weak light stress caused by transpiration rate(Tr2000)with different degree rise,along with the extension of weak light stress duration,while Cond2000 and Ci2000 expression is significantly higher than control,that time is too long to weak light stress results in a decreased photosynthetic production capacity is not reversible.Weak light stress effect of corn leaf physiological aging,weak light processing speeds up the production of ultra oxygen anion,MDA content increased,with the increase of stress level,SOD,POD,CAT enzyme activity brings down-up-down trend,soluble protein content compared to present a trend of reducing the rise,in addition to the CAT enzyme activity reached significant difference between the 3 days and contrast,SOD,POD and soluble protein content and more significant in the 6 day,maximum and soluble protein content in the 6 day.3.The weak light stress resulted in soluble sugar content of leaf decreased,especially when weak light last 6d or more(P < 0.05);and the starch content in grain decreased slightly.Weak light stress lead to leaf Rubp,PEPc and SPS activity decreased significantly(P < 0.05).Compared with CK,sucrose synthase(SS)activity of upper ear grains deceased and that of lower-middle ear grains increased except at weak light duration of 3 d.Starch synthase(SSS)of the upper ear grains reduced gradually with the weak light time,whlie that of the lower-middle ear grains was lower than that of CK at 3-12 d,and maintained the same level to 15 d.The growth rate of dry matter increased after 3-9 d weak light,still significant lower than that of CK.4.The bald tip length of weak light treatments were highter significant than that of CK except that in weak light stress 3 d,and hundred grain weight reached no significant difference with CK.Bald tip longth and empty bar rate increased significantly,but ear length,ear diameter,yield components and yield were all significantly decreased(P<0.05).The yield and yield components of the weak light stress treatments reached linear significant difference with that of CK,but the hundred grain weight except ear of grain number.The weak light duration last 9d or more treatments decreased significantly the grain yield,even made the reduction of yield close to 95%.