The Relationship Between Root System,Water Use Pattern And Grain Yield Of Spring Wheat

As a major world crop,wheat has shown increased yields following advances in breeding.Indeed,breeding have led to significant variations in biological characteristics,including biomass,morphology,life history behavior,harvest index and reproductive allocation.The spring wheat(Triticum aestivum L.)growth is mainly dependent on stored soil water in semiarid regions of Loess Plateau of China,which is quite low during the grain filling period.The relationship between root system,water use pattern and grain yield of spring wheat in semiarid regions is our research purpose.Two experiments were conducted in our research.Experiment 1:In the first pot experiment,the six cultivars released in different period were used in this studies growing in PVC pot with 11c m diameter and 130c m height.In the experiment,every PVC pot only one plant and two water regimes,(1)well-watered treatment(WW):plants maintained at 80%-90%field capacity;(2)water-stressed treatment(WS):withholding the water supply 60 days after sowing(DAS)exception the additional 70 mm water supply at 87 DAS.Experiment 2:The eighteencultivars with similar phenological development selected from 178 cultivars were used in this studies growing in larger PVC cylinders with 0.4 m diameter and 2 m height.37 plants per PVC cylinders(pot)which was equivalent to 300 plant per m~2in field.A total of 70 mm tap wate r(befor sowing the soil water storage in PVC pipe is about 60.3kg),which simulated the effective rainfall of spring wheat growing season in local field,was imposed to each large PVC cylinder from every 10 days after sowing(DAS).The result of experiment were:(1)Under the condition of experiment 1,the grain yield of six cultivars in no competition had not significant difference at two water regimes.The new cultivars have more kernel weight per ear than the old cultivars;but the old cultivars had significantly less harvest index than the new cultivars.(2)New cultivars have more biomass allocation to spike compared old cultivars.Old cultivar’s root ratio significantly more than new cultivars.And the root ratio in water-stressed treatment significantly more than well-water treatment.(3)Old cultivars use more water than new cultivars,but the water use efficiency have inverse trends.(4)Under s condition of experiment 2,the grain yield of eighteen cultivars was positively correlated to water use at reproductive phase,whereas negatively correlated to water use at vegetative phase.(5)The grain yield was varying from 43 to 92 g pot-1,with inverse trends to grain yield was observed in total root biomass for all cultivars.High grain yield of srping wheat was associated with high harvest index and water use efficiency for grain(WUE_G).(6)The grain yield was positively correlated to water use at reproductive phase,whereas negatively correlated to water use at vegetative phase.(7)The root dry weight ang root length density had inverse trends to grain.And the grain yield was negatively correlated to root shoot ratio.The research results show that in the loess plateau semi-arid areas long-term breeding practice,choose a small root system of spring wheat.A small root system with less water use before grain filling is beneficial for grian yield,because which reducing the risk of severe drought occurred during grain filling.The result has the important enlightenment of crop breeding in the future.