Effects Of Different Mulching Models And Fertilization Treatments On Winter Wheat Yield Insemiarid Rain-fed Region

Natural precipitation is the only source of soil water in northwest semiarid rain-fed agricultural region. The region with dry climate, high evaporation, scarce precipitation and the precipitation mainly happens during the fallow period, conflicts with wheat water consumption seriously. Besides, other problem such as poor soil, severe soil erosion and worsening ecology environment severely restricts the growing of wheat, is a potential threat to northwest even China’s food security. This paper focuses on the sustainable development of winter wheat in semiarid rain-fed region; on the basis of traditional straw mulching adjust measures to environment conditions, using local covering and local high density measure, effectively solved the problem of shortage accumulated temperature that caused by straw mulching in high altitude area, and compare with whole field plastic mulching with soil covering on the top of the plastic mulch and bunch-seeding. A field experiments was conducted under different mulching models(bundled straw covering: BSC, mulching used plastic film after harvest: PAH, uncovered and row-seeding: CK) and fertilization treatments(pure nitrogen and P2O5: 90, 120, 150 kg·hm-2, respectively) to reveal yield, water use efficiency, soil water thermal conditions and other agronomic traits information process mechanism on winter wheat, the main results are as follows:1. The mulching models and fertilizer amount had significant effects on grain yield, water use efficiency(WUE), harvest index(HI), spike numbers, grain number per spike and 1000-Grain weight; had significant interaction effect on grain yield, water use efficiency(WUE) and yield components. The best combination is bundled straw covering together with the high fertilizing amount, which significantly enhance the grain yield and water use efficiency. The grain yield reached 5305.0 kg·hm-2 under BSC, which was 24.0% and 37.5% higher than PAH and CK, and the WUE reached 10.8 kg·hm-2·mm-1, which was 20.6% and 33.3% higher than PAH and CK, respectively. BSC yield and WUE under the same fertilizer amount were significantly higher than PAH and CK. The unit area spike numbers that under BSC, which was 27.0% and 42.2% higher than PAH and CK, respectively. At the high and moderate fertilizer amount the unit area spike numbers of BSC is significantly higher than PAH and CK; However grain number per spike and 1000-Grain weight of BSC is reduced. The correlative analysis showed that the grain yield was significantly and positively associated with unit area spike numbers(r=0.929**), grain number per spike(r=0.623) and 1000-Grain weight(r=0.343) were not significantly proportional correlation.2. The mulching ways and fertilizer quantities had significant interaction effect on the 0~200 cm soil moisture, had significant interaction effect on the 0~25 cm soil temperature. Compared to CK, both BSC and PAH increased soil moisture during the whole growth stages, and significant higher than CK at the same fertilizer amount. The soil moisture of BSC was 0.3 and 1.1 percentage point significantly t higher than PAH and CK whole growth stages, before the returning green stage was 0.6 and 0.9 percentage point significant higher than PAH and CK, respectively. The soil moisture of BSC is significantly higher CK at ever growth stages, but after the jointing stage PAH was the best, the 90 ~ 120 cm soil water was significantly changed. The soil temperature of BSC was 1.0 and 1.9 degree Centigrade lower than CK and PAH during the whole growth stages, respectively. Before wintering BSC higher than CK 1.1 degree Centigrade, showed warming effect, but lower than PAH 2.0 degree Centigrade. After the returning green stage was 2.3 and 1.8 degree Centigrade lower than PAH and CK, showed cooling effect, respectively. And PAH show warming effect in the whole stages, which was higher than CK an average of 0.9 degree Centigrade. But between the three kinds of fertilizer amount is no significant differences in different growth stages, the 5~10 cm soil temperature was significant changed. The correlation analysis showed that the grain yield was significant and positively associated with the 0~200 cm soil moisture(r=0.760*); was significant and negative associated with the 0~25 cm soil temperature(r=-0.784*).3. The mulching models had significant effect on singling dry matter accumulation, plant height and grain filling rate; and the fertilizer amount had significant effect on plant height, grain filling rate; both mulching models and fertilizer amount had significant interaction effect on plant height and grain filling rate. Before jointing stage the singling dry matter accumulation is low, their growth rate accelerated after jointing stage, and the differences has gradually become bigger, but remained PAH>CK>BSC from beginning to end, there was no significant difference between fertilizer treatments. Plant height of BSC during whole growth stage is the highest, PAH is second, CK is the lowest; and plant height increased with fertilizer amount improves. The whole filling stage, the grain filling rate were ―slow ~ quickly ~ slow‖ changed trend, the average grain filling rate with PAH is largest, CK is second, BSC is lowest. The maximum grain filling rate of PAH and CK were 4 days ahead of BSC. The average grain filling rate of BSC is low, but filling duration extended obviously. The correlation analysis showed that the grain yield were significantly and negative associated with the singling dry matter accumulation(r=-0.829**), was significantly and positively associated with the plant height(r=0.829**), was no significant positive with the average grain filling rate(r=-0.232).4. The mulching models and fertilizer amount had significant effect on flag leaf relative water content and SPAD. Flag leaf relative water content of CK, before the medium of grain filling stage is the highest; BSC is second and PAH is the lowest. At the end of grain filling stage the flag leaf relative water content dropped rapidly, but the BSC still keep a higher level, which was14.8% and 26.2% percentage point higher than CK and PAH, respectively. And the flag leaf SPAD of BSC, which was 36.1% and 62.9% higher than CK and PAH, respectively. Both the flag leaf relative water content and SPAD increased with fertilizer amount improves. In other word, the BSC had a better health and dry resistance status compare with PAH and CK, this performance increased with fertilizer amount improves. The correlation analysis showed that the grain yield were significantly positive associate with the flag leaf relative water content(r=0.869**) and SPAD(r=0.990**).5. By comparing the grain yield, yield components, soil moisture, soil temperature, the variation coefficient of other agronomic traits and the maximum difference rate of yield under different mulching models and fertilizer amounts, which showed that the mulching models is the predominate factor.