氮肥和密度对胡麻水分、氮素利用率及产量的影响

Effect of density and nitrogen on water and nitrogen utilization and seed yield of oil flax

在大田环境下,设置氮肥(0、75、150 kg·hm^-2)和密度(4.5、7.5、10.5×10^6粒·hm^-2)2因素共9个处理(N0D1、N0D2、N0D3、N1D1、N1D2、N1D3、N2D1、N2D2、N2D3)的随机区组试验,分析了不同施氮量和种植密度组合对旱地胡麻土壤含水量、贮水量、籽粒产量及产量构成因子、水分和氮素利用率的影响。结果表明,氮肥、密度各处理土壤含水量变化主要表现在苗期~青果期0~60 cm土层,以N1D1处理为优,最高达到15.52%;N2D1处理0~200 cm土壤平均含水量为18.25%,其生育季内0~200 cm土壤贮水量亦较最低处理N1D3增加4.62%,具有较好的肥水耦合优势。胡麻产量随处理中施氮量和密度增加呈先降后升趋势,随施氮量变幅为66.58~171.64 kg·hm^-2,随密度变幅为32.42~68.47 kg·hm^-2。籽粒产量和水分利用效率对施氮水平呈现明显的正效应,高氮(N2)较中氮(N1)和不施氮(N0)水平产量上升14.97%~16.05%,水分利用效率增加7.14%~21.75%;而增加密度对胡麻产量和水分利用效率并未有显著影响,组合中均为4.5×10^6粒·hm^-2处理下最高,分别达到1802.00 kg·hm^-2和7.87 kg·hm^-2·mm^-1。增施氮肥显著提高了植株氮素吸收量,高氮(N2)、中氮(N1)较不施氮(N0)分别显著增加82.21%和57.55%;平均氮素吸收利用率则均随施氮量和密度上升而降低,高氮(N2)较中氮(N1)水平显著降低42%,高密度(D3)、中密度(D2)平均氮素利用率分别较低密度(D1)处理显著降低58.45%和35.19%。在试验处理区间内,高氮配合增密不利于提高氮素吸收利用率,N1D1组合氮素利用率最优,为64.3%。氮肥密度互作后,籽粒产量与有效分茎数间(0.688*)、有效分枝数与单株有效果数间(0.877*)均显著相关,且分茎数、分枝数受密度影响程度大于施氮量,而千粒重受限于施氮量更甚,不同施氮水平间变幅达到0.04~0.29 g。因此,氮肥密度互作时,增密对水分利用效率及产量无显著影响,适量氮肥施用可促进胡麻生育前、中期水分有效利用和提高氮素利用率,使胡麻产量及水分利用效率显著增加。在本试验及相似农田生态类型环境下,兼顾节本增效和环境安全,施氮量75~150 kg·hm^-2、种植密度4.5×10^6粒·hm^-2可作为黄土高原干旱半干旱区胡麻高效生产的适宜参考氮肥密度组合。

In order to clarify mechanism of water and fertilizer utilization and establish an optimal cultivation mode in arid land farming of oil flax,a field experiment was conducted with two-factor randomized block test,three planting densities(4.5×10^6,7.5×10^6 plant·hm^-2,and 10.5×10^6 plant·hm^-2),and three nitrogen(N)application rates(0,75 kg·hm^-2,and 150 kg·hm^-2).The effects of density and N application rate on variation of soil water content,soil water storage,yield and yield components,water and N use efficiencies were studied.The results showed that variation of soil water content in 0~60 cm soil layer was reflected at the stage from seedling to fruit stage under density and N fertilizer treatments,besides for optimal treatment in N1D1 up to 15.52%.Fertilizer-water coupling advantage appeared in N2D1 treatment,which had an average soil water content of 18.25%in 0~200 cm soil,and the soil water storage in the 0~200 cm period during the growing season also increased by 4.62%compared with the lowest treatment N1D3.Grain yield and water use efficiency had obvious positive effects on N application rate,yield and water use efficiency under high N level(N2)increased by 14.97%~16.05%and 7.14%~21.75%compared with the levels of medium N(N1)and no N(N0),respectively.The yield of oil flax increased first and then decreased with the increase in N application rate and density in the combination treatments,the variation of grain yield were 66.58~171.64 kg·hm^-2 and 32.42~68.47 kg·hm^-2 with the amount of N application and the density,respectively.It confirmed that density increasing had no significant effect on oil flax yield and water use efficiency for highest yield under 4.5×10^6 plant·hm^-2,reaching 1802.00 kg·hm^-2 and 7.87 kg·hm^-2·mm^-1.N application significantly increased the N uptake of the plants,high N(N2)and middle N(N1)increased by 82.21%and 57.55%,respectively,compared with no N(N0),while the average N utilization decreased with increasing N application rate and density.Nitrogen utilization rate under high N(N2)level significantly reduced by 42%compared to medium N(N1),average N utilization rate in high(D3),medium(D2)density and lower density(D1)treatments significantly reduced 58.45%and 35.19%,respectively.In the experimental treatment interval,high N combined with densification was not conducive to improving N utilization,the N utilization rate of medium N(N1)low density(D1)amount to 64.3%,which was an optimal combination.After the interaction of density and N fertilizers,the numbers of branches and stems were affected by the density more than the amount of N applied,while the 1000-grain weight was more affected by the N application rate,the 1000-grain weight variation reached 0.04~0.29 g under the three N application levels.There was a significant correlation between grain yield and effective number of stems(0.688*),effective number of branches and number of effective capsules(0.877*).Therefore,the increase in density had no significant effect on water use efficiency and yield,the application of appropriate N fertilizer promoted the effective utilization of water in the early and middle stages of flax and increased the N utilization rate.The yield and water use efficiency of flax were significantly increased.In this experiment and similar farmland ecological type environment,the nutrient management model of 75~150 kg·hm^-2 N application rate and 4.5×10^6 plant·hm^-2 planting density can be used as a suitable reference for the efficient production of oil flax in the arid and semi-arid regions for the Loess Plateau.