分根灌溉下水氮耦合对草莓果实品质及产量的影响

本文采用盆栽分根固定干湿灌溉试验研究了水氮耦合对草莓果实品质及产量的影响。试验设置水分和氮肥2个因素,草莓根区设置湿润与干旱(A/B)两个区域,湿润一侧(A)全生育期内土壤相对含水量均为80%±5%,干旱一侧(B)土壤相对含水量设置为20%±5%(重度水分胁迫)、35%±5%(中度水分胁迫)、50%±5%(轻度水分胁迫)3个处理水平;施氮量设置0.5 g(N)×kg~(-1)(低氮)、0.75 g(N)×kg~(-1)(中氮)、1 g(N)×kg~(-1)(高氮)3个处理水平,对照处理(即常规生产模式,CK)A/B两区域均为80%±5%土壤相对含水量、中氮0.75 g(N)×kg~(-1)]水平。研究结果表明:1)分根干湿灌溉显著减少了草莓全生育期灌溉水量,提高了草莓的水分利用效率(WUE),全生育期内干旱一侧(B)土壤相对含水量为20%±5%、35%±5%和50%±5%的水分处理总灌溉水量分别为14.77 L×株~(-1)、16.62 L×株~(-1)和18.47 L×株~(-1),较CK处理(24.62 L×株~(-1))分别减少40.0%、32.5%和25.0%;以中度水分胁迫中氮水平的草莓水分利用效率(WUE)最高,为13.55 g×L-1,较CK处理提高47.1%,而产量没有明显减少;耦合分根干湿灌溉和施氮处理,轻度水分胁迫中氮水平下草莓果实产量最高,较CK处理提高4.4%。2)从对草莓果实品质影响角度分析,中氮及中度水分胁迫处理的草莓果实中Vc含量、可溶性糖含量、有机酸含量和糖酸比分别比CK处理增加63.3%、12.5%、3.9%和8.3%。综合考虑不同水氮耦合处理对草莓果实品质、产量、水分利用效率及对农业环境安全的影响,以湿润一侧(A)保持土壤相对含水量为80%±5%、干旱一侧(B)保持土壤相对含水量为35%±5%,且0.75 g(N)×kg~(-1)施氮水平为设施草莓生产适宜的水肥管理模式。

Effects of water and nitrogen coupling on strawberry yield and quality under partial root-zone irrigation

The effect of water and nitrogen application on efficient utilization of water and fertilizer under partial root-zone irrigation has attracted the attention of scientists around the globe. In order to improve the quality and yield of strawberry along with the utilization efficiency of water and fertilizer, this study examined the effects of integrated water and nitrogen management on the yield and quality of strawberry under partial root-zone irrigation. The main objective of the study was to provide a scientific basis for highly efficient utilization of water and fertilizer of strawberry. In the experiment, two factors (water and nitrogen) were set up with three levels for each factor. The roots of strawberry were well distributed in two zones-wetting and drying zones (A/B). The relative water content of soil was 80%±5% in the wetting zone (A). For the drying zone (B), the relative water content was in three levels, which were 20%±5% (sever water stress, SS), 35%±5% (moderate water stress, MS) and 50%±5% (light water stress, LS). At the same time, nitrogen fertilizer was set at 3 levels, which were respectively 0.50 g(N)·kg^-1 (lower N, LN), 0.75 g(N)·kg^-1 (medium N, MN) and 1.00 g(N)·kg^-1 (high N, HN). The two (A and B) zones of control (CK) were 80%±5% of soil relative water content and medium nitrogen0.75 g(N)·kg^-1] fertilize rate (i.e., the conventional production mode). Based on the test data, the growth, quality and yield of strawberry under different water and nitrogen conditions were analyzed and evaluated using Principal Component Analysis (CPA) and polynomial fitting. The main findings of the study were as follows. 1) Due to partial root-zone irrigation, water utilization significantly dropped while water use efficiency (WUE) improved during the growth period of strawberry. The rates of irrigation water under SS, MS and LS treatments were respectively 14.77 L, 16.62 L and 18.47 L per plant. Compared with the control treatment (which was 25 L·plant-1), irrigate rates for 3 treatments dropped respectively by 40.0%, 32.5% and 25.0%. Under MSMN treatment, WUE of strawberry was 13.55 g·L^-1, 47.1% higher than that under CK treatment; but the yield change was not significant. The yield of strawberry was the highest under LSMN treatment among all treatments, which increased 4.4% over that under CK treatment. 2) The contents of Vc, soluble sugar, organic acid and sugar acid ratio of strawberry fruits under MSMN treatment were respectively 63.32%, 12.48%, 3.90% and 8.31% higher than that under CK treatment. The effects of integrated water and nitrogen management on the yield, quality and WUE of strawberry indicated that the most suitable model of water and nitrogen management for the production of strawberry was 0.75 g(N)·kg^-1 nitrogen rate with relative soil water content of 80%±5% in the wet zone and 35%±5% in the dry zone (i.e., MSMN).