Floret Development And Grain Setting Of Winter Wheat In Response To Nitrogen Availability Under Irrigation And Rainfed Conditions

The grain yield of wheat is composed of spikes, grain weight, grain number per square meter.Improving grain number per spike is one of the key ways to improve wheat yield. The formation of small grain number process including floret differentiation and development,degradation, and strong physiological processes for example. So the physiological mechanism of grain number formation and its response to the cultivation regulation, the growth period of wheat breeding for high yielding varieties, cultivation management and so on has great meaning in the research of theory and significance reference. This test is under field conditions, choosing Shannong 20 as the experimental material, setting one water treatment(R,), three water treatment(W, jointing stage, flowering water) in two levels, three levels of N is 0(N0), 240(N1), 360(N2) kg hm- 2, the main results were as follows:1 W×N interaction on the influence of floret developmental degree in different spike position of wheatWater and nitrogen fertilizer for different spike position 1, 2, floret development effect was not significant. Water and nitrogen fertilizer significantly influenced the the third floret in basal and apical spike, the fourth floret in basal spike. Water effect on the fourth floret in central spike was significantly than nitrogen effect. The floret(5-7) in higher position failed to develop W10 stage, showing that the processing of high floret will not be able to develop into fertile floret, but increasing nitrogen application significantly increased the development degree of different spike position. The fifth floret of basal, central, apical spike of RN0 treatment can develop to W4.2, W4.5, W4.2 stage, while the floret of RN1 treatment can develop to W5.5, W6.5, W5. The fifth floret of basal, central, apical spike of WN1 treatment can develop to W5.8, W6.75, W5.8 stage, while the floret of WN0 treatment can develop to W4.5, W5.2, W4.5 stage. Two water conditions that increasing nitrogen application significantly improved the floret development degree, and increasing nitrogen can alleviate the effects of water deficit on the floret development. Under the same nitrogen fertilizer condition, The developmental degree of the fifth floret in basal, central, apical spike was WN0>RN0, WN1>RN1, WN2>RN2 treatment, showing that water effect significantlyincreased the development degree of the floret. RN0, RN1, RN2, WN0, WN1, WN2 treatment for the sixth floret of basal and central spike, the seventh floret of basal and apical spike, and the fifth floret showed similar patterns. Although the sixth floret development degree of apical spike under WN2 treatment of was higher than the RN2 treatment, but the difference was not significant, the seventh floret development degree of central spike under WN0, WN2 treatment was higher than RN0, RN2 treatment, but no significant difference.2 W×N interaction on the number fertile floret(FF), number of grains(GN), setting rate(GS), the likely-hood of grain setting and the spikelets that setting grains in different spikelet positionThe number of average fertile florets in different spikelet position in the central spike was most. Irrigation condition, the average number of fertile florets in the apical, central and basal spikelet increased with the increase of N application, with N1 treatment most. Rain-fed conditions, RN1, RN2 treatment of the fertile floret number of the apical, central and basal spike is significantly higher than RN0 treatment, RN1 treatment more than RN2 treatment,but the difference was not significant. Irrigation conditions, the central and apical spike, the average number of fertile florets in rainfed conditions showed similar regulation. In irrigated conditions, the fertile floret number in the basal spike under WN1 treatment was higher than WN0, WN2 treatment, and the difference between treatments was significant. In the same nitrogen fertilizer condition, the average number of fertile florets in the central spike and the apical spike under irrigated were more than rain-fed, and the differences were significant.In irrigated condition, the final grain number under WN1 treatment of the apical, central and basal spike is significantly higher than the average of WN0 treatment, WN2 treatment, WN0,WN2 treatment, no significant difference between the rainfed conditions, the spike in the central, basal and irrigation conditions showed similar regulation, and WN0 treatment was significantly under WN1 treatment grains per spike at the apical spike, WN2 treatment, but did not reach significant difference between WN1, WN2 processing level. In the same nitrogen fertilizer condition, the final number of fertile florets in basal spike under WN0,WN1, WN2 treatment was significantly more than the RN0, RN1, RN2 treatment. The average number of fertile florets in the apical, central and basal spike under WN0, WN1 treatment was in similar regulation, although the fertile florets per spike at the apical spike under WN2 treatment is higher than RN2 treatment, but no significant differences between the treatments.In irrigated condition, with the increase of N application, the grain setting of the central,basal spike was increasing then decreasing, with the highest of N1 treatment, but the grainsetting in the apical spike with the increase of N application was gradually reduced, rain-fed conditions consistent with spike setting rate under different irrigation performance. Under the condition of same N application, the setting rate of fertile floret in the central and basal spike in WN0 treatment was higher than RN0 treatment, and the apical spike was under RN0 treatment. In irrigated condition, the setting rate under N1, N2 treatment in different spike was more than rainfed condition.In irrigated condition, regardless of the effect of nitrogen fertilizer, the likely-hood of grain setting in different spikelet position was highest of the first grain, namely the G1 > G2 >G3 >G4. The spikelets number of 1, 2 grains of WN1 treatment increased by 14.3% and 9.5%respectively, compared with WN0, WN2 treatment. The spikelets number of 3, 4 grains of WN1 treatment increased by 23.5% and 29.4% respectively, compared with WN0, WN2 treatment. The spikelets number of 5 grains of WN1 treatment increased by 58.3% and 91.7%respectively, compared with WN0, WN2 treatment. The influence of WN1 treatment on high grain of spikelet number was much more than low grain.The first grain of spikelet number under WN2 and RN2 treatment is consistent, N1, N0 treatment for irrigation than rain-fed, WN1, WN0 treatment increased by 10.5% and 12.5%respectively than RN1, RN0 treatment. Two grains may be tough little spikes and one grain performance regulation is consistent, WN1, WN0, WN2 treatment increased by 10.5%, 20%and 18.8% respectively than RN1, RN0, RN2 treatment. The third grain of WN1, WN0, WN2 treatment increased by 41.7%, 62.5% and 33.3% respectively than RN1, RN0, RN2 treatment.4 W×N interaction on wheat yieldWN0, WN1 treatment of spike numbers, grain number per spike, 1000-grain weight and yield was higher than RN0, RN1 treatment, and the differences reached significant level.WN2 treatment of grain numbers per spike, 1000-grain weight and yield were significantly higher than that of RN2 treatment, but no significant difference between spike number.Irrigated conditions, with the increase of N application, the difference was not significant between spike number per square meter, increasing nitrogen application significantly increased the grain number per spike and yield, with the highest WN1 treatment. WN0 treatment of grain was slightly higher than the WN1, WN2 treatment, including WN1 treatment, no significant difference between WN2 treatment. Rain-fed conditions, no significant difference between spike number in RN1, RN2 treatment, but significantly higher than that RN0 treatment, this is because the rainfed reduced tiller number of wheat.With the increasing of N application, differences between grain number per spike and yield were significantly, with RN1 dealing with highest, lowest RN0 treatment. The grain differencebetween RN1, RN2, RN0 treatment reached significant level(p < 0.05). RN1, RN2 treatments were below RN0 treatment. The differences between RN0 and RN1, RN2 treatment are significant(p < 0.01), the difference between RN1, RN2 treatment was not significant, lowing than RN0 treatment.