适宜施氮量提高温室砂田滴灌甜瓜产量品质及水氮利用率

为解决设施砂田甜瓜生产中的水肥瓶颈问题,该文通过大田试验,研究西北旱区设施砂田甜瓜传统水肥管理与滴灌施肥处理对不同生育时期甜瓜生长、产量、品质及水氮利用率的影响,从而确定甜瓜高效的灌溉方式及适宜的氮肥用量。试验设置了2个对照处理:大水漫灌不施氮肥(CK0)和大水漫灌传统施氮(CK),并在灌水量减少40%的滴灌条件下设置了4个氮肥水平:不施氮(T1)、传统施氮量N 180 kg/hm2(T2)、减氮40%即N 108 kg/hm2(T3)、增氮40%即N 252 kg/hm2(T4),共6个处理。结果表明:滴灌施肥处理较对照在甜瓜生长后期光合、植株干物质及氮素积累量等生理、生长指标均显著提高,甜瓜增产7.40%~14.35%,水、氮利用率分别提高28.81%~40.65%和22.78%~77.22%,果实品质中可溶性固形物及Vc含量也显著提高,硝酸盐含量显著降低,且滴灌可减少砂层含土量,从而延长砂田的使用年限。相同滴灌条件不同氮水平处理间,甜瓜植株干物质及氮素积累量随施氮量的增加而增加,而光合指标、产量、品质及水氮利用率则表现出先增加后降低的趋势,其中以T2和T3处理的甜瓜产量、品质和水氮利用率最高。综合分析表明,滴灌施肥是西北旱区设施砂田甜瓜栽培优质高产、高效和节水节肥的水肥管理模式,适宜的氮肥施用量为108~180 kg/hm2。

Optimal drip fertigation amount improving muskmelon yield, quality and use efficiency of water and nitrogen in plastic greenhouse of gravel-mulched field

Abstract: In order to solve water and fertilizer problem in the actual production of muskmelon in plastic greenhouse of gravel-mulched field, the effects of the different management mode of water and fertilizer on plant growth, yield, quality and use efficiency of water and nitrogen of muskmelon in plastic greenhouse under gravel-mulched field were studied in 2013 , the study was to set up a new model of water-saving, good quality and high yield evaluation for muskmelon cultivation in the arid regions of northwest china. The experiment site was Gaolan Experiment Station in Lanzhou city, Gansu province, China. Six treatments were designed including two control treatments and four drip fertigation treatments, control treatments including two nitrogen levels (CK0 and CK, N 0 and 180 kg/hm2) under the traditional flood irrigation, and drip fertigation treatments including 4 nitrogen levels (T1, N 0 kg/hm2; T2, N 180 kg/hm2; T3, N 108 kg/hm2; T4, N 252 kg/hm2 ). Each block was 3 m×4.8 m with 30 plants; blocks were separated by 70 cm deep plastic film to prevent the cross penetration of water and fertilizer. The photosynthesis rate was measured with portable photosynthesis systems between 8:00 am -18:00 pm on fruit enlarging period. The dry matter accumulation and N accumulation amount at different growth stages, yield, quality, use efficiency of water and nitrogen of muskmelon were measured. The results showed that drip fertigation treatments could improved the photosynthesis of muskmelon, and the photosynthesis rate of T2 treatment increased by 21.26% and 13.90% respectively compared to CK at 12:00 and 14:00, and average water use efficiency of drip fertigation treatments increased by 2.55%-12.44% compared to CK. Dry matter accumulation of muskmelon plant had no significant difference between flood irrigation and drip irrigation under the same nitrogen levels between seedling stage to flowering stage, dry matter accumulation of T2 treatment increased by 22.89% and 28.10% significantly (P<0.05) compared to CK respectively at expanding stage and maturing stage. Compared to CK, the drip fertigation treatments increased the yield by 7.40%-14.35%, soluble solid content by 5.00%-9.38%, vitamin C content by 11.52%-16.13%, and the use efficiency of water and nitrogen by 28.81%-40.65% and 22.78%-77.22%, respectively, but reduced nitrate content by 15.55%-27.93%. Besides, drip irrigation could reduce mass fraction of soil in the sand layer, so the service life of gravel-mulched field was extended. Between different nitrogen levels under drip irrigation, dry matter and nitrogen accumulation of plant increased with increasing nitrogen fertilization level. The yield of T2 and T3 treatments were 38189.34 and 36585.15 kg/hm2 respectively, and soluble solid content were 17.5% and 17.1%, respectively, which were the highest among all the treatments. Excessive nitrogen fertilizer could reduce vitamin C content and increase nitrate content of fruit. Nitrogen use efficiency of T3 treatment was 37.73%, which was the highest among all the treatments, and increased by 44.34% and 42.81% compared to T2 and T4 treatments respectively. Water use efficiency of T2 and T3 treatment were 30.07 and 29.67 kg/m3, respectively, which was the highest among all the treatments, and increased by 20.76% and 19.16% compared to T1 treatment, respectively. The yield, quality and water and nitrogen use efficiency were the highest for T2 and T3 treatments. So, drip fertigation was efficient management mode of water and fertilizer for muskmelon cultivation in plastic greenhouse of gravel-mulched field in the arid area of northwest china, and the optimal nitrogen rate was 108-180 kg/hm2.