不同水氮处理对膜下滴灌春大豆根系生长及产量的影响

Effects of Different Water and Nitrogen Treatments on Root Growth and Yield of Spring Soybean under Mulched Drip Irrigation

为探究不同水氮处理对膜下滴灌春大豆根系生长和产量的影响规律,以合农71为试验材料,进行水、氮两因素裂区田间试验。分别设主区总灌水量1875 m^(3)·hm^(-2)(W1)、2625 m^(3)·hm^(-2)(W2)、3375 m^(3)·hm^(-2)(W3),副区总施氮量0 kg·hm^(-2)(N0)、120 kg·hm^(-2)(N1)、240 kg·hm^(-2)(N2),研究9种水氮处理组合对春大豆不同生长时期0~100 cm土层根干重、侧根长、侧根表面积和产量的影响。结果表明:增加灌水量与施氮量均可增加0~100 cm土层大豆根干重、总侧根长和总侧根表面积。7月15日(荚期)和8月15日(鼓粒期),0~20 cm土层根干重分别占总根干重的75.37%~82.43%和71.97%~85.26%,7月15日W_(3)N_(2)处理0~20 cm土层根干重密度最大,较W_(3)N_(2)和W_(3)N_(0)处理分别增加9.84%和17.75%。总侧根长和总侧根表面积分别在8月15日和7月15日达到峰值,均以W_(3)N_(2)处理表现最好。同时增加灌水量与施氮量可显著提高产量和百粒重,而对单株荚数与单株粒数的影响较小。W_(3)N_(2)处理产量最高,较W_(3)N_(2)和W_(3)N_(0)处理分别增加5.70%和14.80%,较W1N1处理高49.76%。同一施氮水平下,灌溉水利用效率与氮肥偏生产力均随灌水量的增加而降低;同一灌水条件下,灌溉水利用效率与氮肥偏生产力均在N1水平达到最高。鼓粒期根干重、侧根长度和侧根表面积与产量均呈显著正相关。综上,增加灌水量和施氮量主要提高了膜下滴灌春大豆0~40 cm土层根干重密度、侧根长密度和侧根表面积密度。根系发育良好是W_(3)N_(2)处理获得高产的关键,本研究条件下,膜下滴灌春大豆适宜的灌水量为3375 m^(3)·hm^(-2),施氮量为120 kg·hm^(-2),可实现最大总根干重119.80 g·m^(-2),总侧根长1910.58 m·m^(-2),总侧根表面积2.64 m2·m-3,产量6083.10 kg·hm^(-2)。

In order to explore the effects of different water and nitrogen treatments on root growth and yield of spring soybean under mulched drip irrigation,we used Henong 71 as the test material and carried out water and nitrogen two-factor split-plot test in the field.We set up the total irrigation amount in the main area of 1875 m3􀅰ha^(-1)(W1),2625 m3􀅰ha^(-1)(W2)and 3375 m3􀅰ha^(-1)(W3),the total nitrogen application rates in the secondary area of 0 kg􀅰ha^(-1)(N0),120 kg􀅰ha^(-1)(N1)and 240 kg􀅰ha^(-1)(N2),and studied the effects of nine water and nitrogen treatment combinations on dry root weight,lateral root length,lateral root surface area and yield of 0-100 cm soil layer at different stages of spring soybean.The results showed that the dry root weight,total lateral root length and total lateral root surface area of spring soybean in 0-100 cm soil layer increased by increasing irrigation amount and nitrogen application amount.On July 15(pod stage)and August 15(seed filling stage),the dry root weight of 0-20 cm soil layer accounted for 75.37%-82.43%and 71.97%-85.26%of the total dry root weight,respectively.On July 15,the dry root weight density of W_(3)N_(2) treatment was the highest in 0-20 cm soil layer,which was 9􀆰84%and 17.75%higher respectively than those of W_(3)N_(2) and W_(3)N_(0) treatments.The total lateral root length and total lateral root surface area reached peak on August 15 and July 15,respectively,and W_(3)N_(2) treatment performed the best.The yield and 100-seed weight could be significantly increased by increasing irrigation amount and nitrogen application rate at the same time,but the pods and seeds number per plant were affected less.The highest yield was obtained under W_(3)N_(2) treatment,which was 5.70%and 14.80%higher than those under W_(3)N_(2) and W_(3)N_(0) treatments respectively,and 49.76%higher than that under W1 N1 treatment.Under the same nitrogen application level,the irrigation water use efficiency and nitrogen fertilizer partial productivity decreased with the increase of irrigation water.Under the same irrigation conditions,the irrigation water use efficiency and nitrogen fertilizer partial productivity reached the highest in N1 level.The dry root weight,lateral root length and lateral root surface area of seed-filling stage were positively correlated with yield.In summary,the increase of irrigation water and nitrogen application rate mainly increased the dry root density,lateral root length density and lateral root surface area density in 0-40 cm soil layer of spring soybean under mulched drip irrigation condition.Well developed root is the key factor of high yield of W_(3)N_(2).Under the conditions of this experiment,the suitable irrigation amount of spring soybean under mulched drip irrigation was 3375 m3􀅰ha^(-1),and the nitrogen application rate was 120 kg􀅰ha^(-1).Under this condition,the maximum total dry root weight reached 119.80 g􀅰m^(-2),the total lateral root length was 1910.58 m􀅰m^(-2),the total lateral root surface area was 2.64 m^(2)􀅰m^(-3),and the yield was 6083.10 kg􀅰ha^(-1).