Effects Of Different Water And Phosphorus Condition On Yield Formation In Three Spring Wheat Cultivars

A potted plant experiment was conducted under an auto-rain-shelter to investigate three different spring wheat cultivars for growth,water use efficiency,root-shoot ratio and grain yield as affected by water and phosphorus regimes.Two soil water treatments were employed:drought stress(W₀,45～50%of field water capacity) and well-water supply(W₁,75～80%of field water capacity).Three phosphorus treatments were also employed:no phosphorus(P₀,added 0.00g P₂O₅/kg dried soil),suitable phosphorus(P₁,0.10g P₂O₅/kg dried soil) and high phosphorus(P₂,0.25g P₂O₅/kg dried soil).The wheat selected as bellow:'heshangtou'(H,a native widely plant used during 50s and 60s of latest century),'gaoyuan602'(G,cultivated at late 70s in Qinghai and introduced in Gansu at 80s) and 'longchun8275'(L,the neoteric cultivar cultivated in 1996).In order to analyze and study the effects of water and phosphorus on the traits related to yield formation of different spring wheat,shoot biomass,root biomass,height and leaf area were measured in jointing,flowering and mature stage. Grain yield were also measured in mature stage.The main results were listed as follows:1.Height and leaf area,dry mater accumulation(including root and shoot biomass), water consumption,yield components(including grain yield,thousand-gain weight, spike number,gain number per spike,number of valid spike and head length) and water use efficiency were influenced uniformly by water and phosphorus.Under well-water supply,the effects were the largest while employed with phosphorus.The following was drought stress with phosphorus.The application of drought stress without phosphorus had the lowest effect on them.2.The results showed that well-water supply and phosphorus fertilizer significantly increased the growth,accumulation of dry matter,water use efficiency and yield components,and the remarkable positive effects of phosphorus boosted up with the improvement of moisture.In spite of the growth and accumulation of dry matter in high phosphorus increased when compared to that in middle phosphorus treatments, water use efficiency can't be improved accordingly,causing the yield can not be improved.So based on the economic benefit,a moderate phosphorus supply strategy was better.3.Water and phosphorus deficit increased root-shoot ratio at early stage,but the effect of phosphorus was not significant.In middle and later periods,root-shoot ratio increased remarkably with the using of phosphorus,but water made no difference to them.There was no much difference between suitable phosphorus and high phosphorus treatments.And the root-shoot ratio of different cultivars declined with the advance of breeding decades.4.Harvest indexes raised with the improvement of water-supply level and declined along with the P rate while the difference between fertilization treatments was not significant.Treatments under suitable phosphorus were slightly lower than high phosphorus,and the difference between them was indistinctive.Under drought stress, the measurement order of different cultivars was:G＞L＞H.Then under well-water supply condition,the sequence was:G＞H＞L.Under whatever water condition,there was no significant difference.5.Height,root and shoot biomass,water consumption and yield components of different cultivars all decreased with the advance of breeding decades,that was: H＞L＞G.As to shoot biomass,the difference between cultivars was significant.But it was different for thousand-grain weight,spike number and water consumption. Cultivar H was significantly higher than cultivar G and L while the difference between the later two was not significant.The difference of other traits to different variety wasn't significant too.6.The measurement order of leaf area,water use efficiency for biomass and grain yield was:L＞H＞G.Leaf area of cultivar L was higher than cultivar H,and there was no much difference between them.To water use efficiency for biomass and grain yield, the difference was not significant.