Effects Of Phosphorus Levels On Growth Characteristics And Yield In Winter Wheat Under Water-saving Cultivation

In order to clarify the regulation effect of phosphorus application amount on the growth,development characteristics and yield in winter wheat under water-saving cultivation consitions,field experiments were arranged in a split design by which the effects of phosphorus levels on the population growth traits,yield,and gene expression were investigated.The main results are as follows:1.Under water-saving condition?only one irrigation in spring performed at jointing?,drastic effects of phosphorus levels were observed on total stem number,LAI,and dry matter accumulation among the P level treatments.The total stem numbers,LAI,and population biomass at various growth stages were increased by the eleveated P applied amounts.Compared with Shixin 828,Jimai 22 were higher on the population growth traits than under various P application levels.2.The chlorophyll contents?Chl?were elevated by the increased P levels in tested wheat cultivars under water-saving condition.So were the photosynthetic parameters,such as net photosynthetic rate?Pn?,transpiration rate and stomatal conductance.However,the intercellular CO₂ concentration was lowered along with the increase of applied P levels.Compared Shixin 828,Jimai 22 were higher on Chl and Pn under various P level treatment.These results suggested that suitable increase of P level promote the photosynthetic function of winter wheat under water-saving cultivation.3.Similar effects of P level on the activities of protective enzymes?SOD,CAT,and POD?and soluble sugar and soluble protein were found in tesed wheat cultivars among the P level treatments,showing that higher activities of SOD,POD and CAT and more amounts of soluble sugar and soluble protein under high P level treatment.Compared with Shixin 828,Jimai 22 were higher on activities of protective enzymes and soluble sugar and protein amounts than Shixin 828.These results indicated that increase of P level can promote the activities of protective enzymes and enhance the biochemical metabolism of sugar and nitrogen.4.Under P₀ treatment,the yields of the tested varieties were the lowest among the P level treatment.Both Jimai 22 and Shixin 828 increased yields significantly under P₆₀ and P₁₂₀ treatment with respect to P₀,and the highest yield was found under P₁₂₀ treatment.The harvest index?HI?,spikes per planting area,grains per spike and 1000-grain weight under different treatments were shown in an order P120>P60>P0.Compared with Shixin 828,Jimai 22 were shown to be improved on yield,harvest index,and the yield components under different levels.5.Compared with P₀,totally 1806 genes were identified to be differentially expressed in leaves,including 767 to be up-regulated and 1039 down-regulated.These differential genes are categorized into functional groups of cell components,binding,cell response and metabolic processes and mainly associated with hormone signal transduction,plant-pathogen interaction,phenylalanine metabolism,terpenoid skeleton biosynthesis,phosphatidylinositol signaling system,galactose metabolism,and linolenic acid metabolism.Likewise,a total of 2947 genes were found to be differentially expressed in grains,of which,993 were up-regulated and 1954 down-regulated.These differential genes are overrepresented by biochemical pathways of phenylpropanoid biosynthesis,photosynthesis-antenna protein,carbon sequestration,glyoxylic acid and dicarboxylic acid metabolism,cysteine and methionine metabolism,and fructose and mannose metabolism.Our results suggested that the responses of leaves and grains to external P levels are closely associated with the modulation on transcription efficiency of a quantity of genes related to cellular structure,molecular function,and biological processes.In summary,the yield,population growth traits and physiological indexes of different phosphorus application levels were analyzed.The P applied by 120 kg/hm² P₂O₅ is recommended in winter wheat cultivated under water-saving condition in Hebei Plain.