Effects Of Plastic Film Mulch And Nitrogen Application Rate On Winter Wheat Yield,Water And Nitrogen Use Efficiency

The field experiment was used to study the effects of plastic film mulching and different nitrogen fertilizer application rates on winter wheat yield,water,and nitrogen utilization efficiency.The experiment included two film levels(ridge mulching and non-mulched),and five nitrogen application rates(N0: 0 kg/ha,N1: 60 kg/ha,N2: 120 kg/ha,N3: 180 kg/ha,N4: 240 kg/ha),totally 10 treatments.The main results were shown as follows:1)The number of stems/ears at different growth stages of winter wheat was lower under ridge mulching than under non-mulched conditions.The number of tillers at jointing stage increased with the increasing of nitrogen application rates for both ridge mulching and nonmulched ones.At flowering stage,the spikes were higher under nitrogen applied treatments than under N0 treatment for both ridge mulching and non-mulched.2)Winter wheat yield was significantly lower under ridge mulching than under nonmulched treatment.The yield of winter wheat increased first and then tended to be stable with the increasing of nitrogen application rates for both ridge mulching and non-mulched ones.Under the ridge mulching conditions,wheat yield was significantly higher under N2,N3 and N4 than under N0 by 12%-46%,and the yield under N2 and N4 treatment was significantly higher than under N1 treatment.Under the non-mulched conditions,wheat yield was significantly higher under nitrogen application treatment than under N0 treatment by 32%-53%.Moreover,there was no significant interaction effect between mulching and nitrogen rates on winter wheat yield.3)There were no significant differences in aboveground biomass and harvest index between ridge mulching and non-mulched treatments.The aboveground biomass was significantly higher under nitrogen application treatment than under N0 treatment.Under the ridge mulching conditions,the aboveground biomass reached the highest(8545 kg/ha)under N4 treatment,while under the non-mulched conditions,the aboveground biomass reached the highest(9090 kg/ha)under N3 treatment.Under the ridge mulching conditions,the nitrogen application rates had no significant effect on the harvest index;while under the non-mulched conditions,the nitrogen application rates significantly affected the harvest index,and the harvest index was significantly higher under N2 and N3 than under N0 treatment,while there were no significant differences between the nitrogen application rates.Moreover,there were no significant interaction effects between mulching and nitrogen rates on aboveground biomass and harvest index.4)The evapotranspiration(ET)was significantly lower under ridge mulching than under non-mulched,but ridge mulching had no significant effect on the water use efficiency of winter wheat.Under the ridge mulching conditions,the ET increased with the increasing of nitrogen application rates,and the ET was significantly higher under N4 treatment than under N0 treatment.Under the non-mulched conditions,the nitrogen application rates had no significant effect on the ET,but the water use efficiency increased first and then decreased with the increasing of nitrogen application rates,and the water use efficiency was significantly higher under N2 treatment than under N0 and N1 treatments.5)The nitrogen partial factor productivity was significantly lower under ridge mulching than under non-mulched treatment.Nitrogen application rates had significant effects on the aboveground nitrogen uptake and nitrogen partial factor productivity.The aboveground nitrogen uptake tended to increase first and then was stable with the increasing of nitrogen application rates for both ridge mulching and non-mulched ones.The nitrogen partial factor productivity decreased significantly with the increasing of nitrogen application rates.Moreover,there were no significant interaction effects between mulching and nitrogen application rates on aboveground nitrogen uptake,nitrogen harvest index,and nitrogen use efficiency.On the whole,under the conditions of freezing injury at the jointing period of wheat in the experimental year,the reasonable nitrogen application rate for winter wheat was 128 kg N/ha and the yield reached 3495 kg/ha under the ridge mulching conditions,while the reasonable nitrogen application rate was 81 kg N/ha and the yield reached 3783 kg/ha under the non-mulched conditions.These suggested that more nitrogen fertilizer needed to be applied under ridge mulching than under non-mulched to maintain the same yield level under the conditions of freezing injury at the jointing period.Therefore,for a given region,whether it is necessary to adopt ridge mulching according to the frequency of frost damage,and accordingly measures should be taken to attenuate the impact of frost damage under the ridge mulching conditions.