Effects Of Seeding Rate And Nitrogen Fertilizer On Grain Yield And Nitrogen Utilization And Its Physiological Regulation

In recent years, Cultivation techniques updating and genetic improvement are becoming an important way in wheat grain yield enhancement. Many new varieties of wheat have been developed by the scientific research units. In order to explore the potential of new wheat species, Corresponding high yield cultivation mode must be established. The nitrogen fertilizer rate and density exert a tremendous influence on the yield of wheat. The plant growth regulators (PGRs) can play a regulatory role on yield components as well. Field experiments were conducted in Jiangpu and Tangquan during 2011-2013 to explore the effect of nitrogen fertilizer rate, seeding rate and PGRs on grain yield, group structure, photosynthetic produce characteristics and nitrogen utilization efficiency. The main results were as follows:1. The effects of seeding rates (150,225,300 and 375×104 seeds/hm2) on grain yield formation, nitrogen uptake and utilization of wheat from different nitrogen fertilizer rate released from 150 to 300 kg/hm2. The results showed that there were significant differences in grain yield and yield components among nitrogen fertilizer rate and seeding density. Yield components show the same trend between optimum sowing and late sowing. Optimum sowing has a higher kernels per spike and thousand kernel weigh than late ones, and the grain yield has a clear advantage at same time. The nitrogen accumulation of the vegetative organs of wheat both at anthesis and mature increased along with the nitrogen fertilizer and seeding rate Increasing, The nitrogen uptake efficiency, nitrogen agronomy efficiency and nitrogen harvest index declined along with the nitrogen fertilizer rate enlarge, while the nitrogen agronomy efficiency to be maximized when the seeding rate at the level of 225×104 seeds/hm2.2. Effects of nitrogen fertilizer rate, seeding rates on photosynthetic characteristics. The results showed that there were significant differences in photosynthetic characteristics among nitrogen fertilizer rate and seeding density. The leaf area of anthesis, SPAD content of flag leaf, nitrogen content of flag leaf, net photosynthetic rate rise along with the nitrogen fertilizer rate increased and seeding rate declined, the activity of SOD, POD were higher significantly, the content of MDA decreased obviously at the same time. Thus help to delay senescence of leaf. The increasing of nitrogen fertilizer rate is also profitable for the activity of NR and GS, what is more, it has a positive function on the assimilation of nitrogen.3. The effects of seeding rates (150,225 and 300×104 seeds/hm2) on grain yield formation and nitrogen uptake and utilization of wheat from different PRGs application. Spraying effects of the plant growth regulators decreased the yield of wheat when the planting density at the level of 150 seeds/hm2. Tebuconazole Thiram(TT) and Jinfeng(JF) can improve the yield of wheat at the level of 225 and 300 seeds/hm2, meanwhile choline chloride(CC)’s promoting effect is not obvious. The PGRs also have a Promoting effect on grain dry matter accumulation. The LAI, SPAD, dry matter accumulation after anthesis, photosynthetic capacity of the wheat sprayed by TT and JF were higher than that of wheat which was have no treatment, this phenomenon was sharp especially when the planting density at the level of 225 and 300 seeds/hm2. Under the JF and CC treatment, the activity of NR, GS were higher significantly. TT and JF can improve the nitrogen accumulation both anthesis and mature at the level of 225 and 300 seeds/hm2.Under TT and JF treatment, nitrogen uptake efficiency have a obviously advance when the seeding rate at the level of 300 seeds/hm2.To sum up, the adjustment function of nitrogen rate, seeding rate and the PRGs can change the photosynthetic characteristics which Has a positive promotion in dry matter accumulation and nitrogen transfer, and then the grain yield increased. In this study, the nitrogen fertilizer in the range of 225-300 kilogram per hectare cooperated with 225 seeds/hm2 can make the most reasonable components of yield, and we can obtain the highest yield in these conditions. In addition, Spraying Tebuconazole Thiram and Jinfeng in the heading stage can be further improved the yield of wheat which under D225 and D300 treatment, and play an active role in nitrogen uptake efficiency at the same time.