水肥互作对滴灌玉米氮素吸收、水氮利用效率及产量的影响

优化水、氮供应是实现作物高产与水肥资源高效利用的有效途径.本文研究了田间试验条件下，水(4500、6750、9000 m³·hm^-2)、氮(0、225、330、435、540 kg·hm^-2)互作对高密度(≥105000 株·hm^-2)滴灌玉米干物质积累、氮素吸收及产量的影响.结果表明: 玉米干物质积累与吸氮量均随灌溉和施氮水平的增加明显升高,当施氮量大于435 kg·hm^-2和灌溉量大于9000 m³·hm^-2时则呈减少趋势.完熟期玉米干物质积累对灌水的响应表现为W₆₇₅₀(36359 kg·hm^-2)>W₉₀₀₀(35077 kg·hm^-2)>W₄₅₀₀(33451 kg·hm^-2),施氮对玉米吸氮量的变化表现为N₄₃₅(459.9 kg·hm^-2)>N₅₄₀(458.1 kg·hm^-2)>N₃₃₀(416.3 kg·hm^-2)>N₂₂₅(351.3 kg·hm^-2),N₄₃₅比N₃₃₀、N₂₂₀分别升高9.1%、32.7%,N₅₄₀比N₄₃₅降低0.6%.在施氮量0～435 kg·hm^-2范围内,玉米最大氮素吸收速率随施氮量增加而升高,在施氮量为435 kg·hm^-2时达最大(6.57 kg·hm^-2·d^-1).灌水与施氮均可显著增加玉米产量、穗粒数和穗粒质量,二者有明显的正交互作用,且以氮为主效应.在施氮0～435 kg·hm^-2范围内,氮肥利用率随施氮量的增加而升高,此后反而降低;灌溉水分生产率随施氮量升高而增加,随灌水量增加而明显下降,灌溉定额为4500～6750 m³·hm^-2时,灌溉水分生产率可达2.57～3.80 kg·m^-3.玉米最高产量18072 kg·hm^-2的施氮量为567.0 kg·hm^-2.最佳经济施氮量为427.9～467.7 kg N·hm^-2时，玉米产量在17109～17138 kg·hm^-2,氮素偏生产力和氮肥利用率分别达122 kg N·hm^-2和45.0%.水氮一体化施肥可实现滴灌玉米高产协同水、氮利用效率的共同提高.

Response of water coupling with N supply on maize nitrogen uptake,water and N use efficiency,and yield in drip irrigation condition.

Water and nitrogen are two major limiting factors for upland crop growth and development in arid region. Optimizing regulation irrigation schedule, rates and coupling with N fertigation is an effective way for realizing crop production improvement as well as water and nutrient use efficiency enhancement. In the present study, a field trial was carried out to study the influence of water (4500, 6750, 9000 m³·hm^-2) coupling with N (0, 225, 330, 435, 540 kg·hm^-2) supply on maize dry matter accumulation, N uptake, yield and nitrogen fertilizer use efficiency in drip irrigated high cultivated density (≥105000 plant·hm^-2) condition. There was an obvious tendency that the amounts of corn dry matter accumulated and plant N absorbed increased with levels of water and N supply, however, those decreased gradually when the N applied rate beyond 435 kg·hm^-2 and irrigation level above 9000 m³·hm^-2. For instance, the effect of irrigation level on corn dry matter accumulation order exhibited W₆₇₅₀ (36359 kg·hm^-2)>W₉₀₀₀(35077 kg·hm^-2)> W₄₅₀₀ (33451 kg·hm^-2), the sequence of amount of N absorbed showed N₄₃₅(462.0 kg·hm^-2) > N₅₄₀ (459.4 kg·hm^-2)> N₃₃₀ (423.4 kg·hm^-2)> N₂₂₅(348.1 kg·hm^-2), the amount of N absorbed in N₄₃₅ treatment increased by 9.1% and 32.7%, respectively, in contrast with treatments of N₃₃₀ and N₂₂₀, whereas, the amount of N absorbed in N₅₄₀ decreased by 0.6% than that in N₄₃₅ treatment. The highe st N absorption rate increased with N application rate increasing within N supply range of 0-435 kg·hm^-2, it reached peak value of 6.57 kg·hm^-2·d^-1 at N application rate of 435 kg·hm^-2, then had decline trend with increasing N rate. Both irrigation and N supply exerted a significant role on maize yield as well as yield component of kernel number per spike and kernel mass per spike. An obvious positive interaction was obtained between water and nitrogen; moreover, the effect of N on yield was substantially higher than that of irrigation. N fertilizer use efficiency increased with increasing N level within N supply range of 0-435 kg·hm^-2, and then dropped markedly when N rate above 435 kg·hm-2. It was found that the water productivity of irrigation (WP_#em/em#) increased with increasing N level, while, that decreased with increasing irrigation rate. At the suitable irrigation range of 4500-6750 m³·hm^-2, the WP_i of 2.57-3.80 kg·m^-3 could be achieved. The maximum corn yield of 18072 kg·hm^-2 was reached at N rate of 567.0 kg·hm^-2. The best N rate of 427.9-467.7 kg N·hm^-2 obtained the optimum yield of 17109-17138 kg·hm^-2, with the nitrogen partial factor productivity of 122 kg N·hm^-2 and nitrogen use efficiency of 45.0% reached. In sum, optimizing water coupling with N supply was the effective strategy for realizing corn yield improvement as well as resources of water and N use efficiency in drip irrigation condition in arid region.