Effects Of Foliar Spraying 6-BA On Photosynthate Allocation And Transfer In The Reproductive Stage And Yield Of Maize

The use of growth regulators to control the growth and development of crops and to give full play to and utilize the potential of crops has become an effective measure to improve yield and quality in the standardized cultivation of many crops(such as cotton,rice and rape).On corn and other staple crops,people have also made some research on the development and application of growth regulators to regulate the growth and development of crops,improve the yield and improve the quality,but the application effect in the field is not ideal.A field plot experiment was conducted to investigate the effects of spraying 6-BA solution at different concentrations(50 mg/L,100 mg/L,200 mg/L,500 mg/L and 1000 mg/L)on the photosynthetic product distribution and yield of the popular maize variety “zhengdan 958”.The results show that:(1)Spraying different concentrations of 6-BA could improve the net photosynthetic rate and stomatal conductance of maize ear-leaf and non-sprayed leaves at the upper part under high light intensity,enhance their photosynthetic capacity,and significantly increase the content of chlorophyll a and total chlorophyll in the ear-leaf at the later growth stage of maize plants,delay the degradation of chlorophyll and prolong the functional period of photosynthesis.(2)For naturally growing maize plants,when they enter reproductive growth,the content of soluble sugar in leaves-sheath-stem presents a concentration gradient which gradually increases significantly.But the content of soluble sugar in stem is significantly higher than that of bract and young corncob(corncob & grain).Starch content in each organ was low,but there was a gradually increasing concentration gradient between leaf-sheath-stem-bract-young corncob(corncob & grain).(3)After spraying 6-BA on corn plants for 7 days,the content of soluble sugar and starch in ear-leaf and soluble sugar in bracts increased,while the content of soluble sugar and starch in stem and sheath increased significantly.However,with the extension of growth time to 28 days after spraying,the soluble sugar and starch content in ear-leaf and bract hardly changed,while the soluble sugar and starch content in sheath,stem and corncob decreased significantly,only the soluble sugar and starch content in grains increased significantly.However,except grains,spraying 6-BA solution did not affect the concentration gradient of soluble sugar and starch among different organs.(4)After spraying 6-BA on maize plants,the content of soluble protein and free amino acid in bract and sheath decreased,and the content of soluble protein in panicle axis increased significantly after spraying 14 days,but decreased significantly after spraying 28 days,only the content of soluble protein and free amino acid in grain increased.At the same time,spraying 6-BA solution had no obvious effect on the content of soluble protein and free amino acid in leaves.(5)After spraying 6-BA on corn plants for 7 days,the biomass of leaves,sheaths,stems,bracts and corncobs increased significantly,but this increased effect gradually disappeared with the extension of growth time.There was no significant difference in the total biomass between the spraying group and the control group,which showed that spraying 6-BA only made the rapid growth time of leaves,sheaths,stems,bracts and corncobs advance.When maize was fully mature,the biomass of leaves,sheaths,stems,bracts and corncobs of 6-BA treated plants decreased,but the biomass of grains increased significantly,which showed that 6-BA treated plants improved the transfer quantity and transfer rate of photosynthetic products in various vegetative organs and tissues to grains,and the contribution rate of photosynthetic products in bracts to the increase of grain weight increased significantly.(6)In terms of concentration effect,there was no significant difference between the effects of spraying different 6-BA solutions on carbon and nitrogen compounds content and biomass and yield traits in different organs of corn.Compared with each other,the effects of 50 mg/L and 100 mg/L are the best.In summary,spraying 6-BA solution with proper concentration on the "three-ear-leaves" of maize in the silking stage is beneficial to improve the photosynthetic rate of maize plants under high light intensity,enhance the photosynthetic capacity in the later growth stage and prolong the photosynthesis function period;At the same time,it can promote the transportation and distribution of photosynthetic products and nitrogen nutrition from vegetative organs to grains,thus effectively improving the yield per unit area of corn.