花铃期棉田速效养分时空变异特征及对棉花产量品质的影响

试验于2004年在河南安阳(黄河流域黄淮棉区)和江苏南京(长江流域下游棉区)大田进行。氮素设0、120、240、360和480 kg hm^-2(分别用N0、N1、N2、N3、N4表示) 5个水平, 磷、钾施用量分别为185 kg hm^-2和118 kg hm^-2, 研究花铃期棉田土壤速效养分时间、空间变异特征及对棉花产量品质的影响。结果表明, 随着生育进程, 两试点N0处理0~60 cm土壤各层碱解氮呈先降低后升高的趋势, 其他4个处理先呈现下降趋势, 棉田追肥后, 含量明显增加, 之后明显降低, 吐絮后又开始回升; 两试点速效磷、速效钾含量均表现为先降低后升高的趋势。0~60 cm土壤各层速效养分含量随深度的增加呈下降的趋势。相同土层碱解氮、速效磷含量随距棉株水平距离的增加, 南京N1、N2、N3、N4处理呈下降趋势, N0处理水平变异特征不明显; 南京碱解氮含量时空变异较安阳显著, 安阳速效磷含量时空变异较南京显著。南京0~60 cm、安阳20~60 cm土层速效钾含量表现为随距棉株水平距离的增加均呈下降趋势, 而安阳0~20 cm呈现相反趋势。安阳、南京分别以360 kg hm^-2和240 kg hm^-2施氮水平棉花产量构成相对合理、皮棉产量最高、纤维长度和比强度较优。因此, 不同生态区应根据花铃期棉田速效养分时空变异特征, 确定适宜施肥量, 提高棉花产量品质。

Spatial and Temporal Variability of Available Nutrient in Cotton Field at Flower and Boll Stage and Its Effect on Lint Yield and Fiber Quality

Flower and boll stage is a key period for lint yield and fiber quality. Studying the spatial and temporal variability of available nutrient in cotton field at flower and boll stage can provide theoretical base for exploring the physiological measurements to improve lint yield and fiber quality. The field experiments were carried out in 2004 at application levels of 0, 120, 240, 360, and 480 kg N ha^-1(marked N0, N1, N2, N3, N4 respectively), 185 kg P ha^-1 and 118 kg K ha^-1 in Anyang and Nanjing, the typical representatives for ecological regions in Yellow River Valley and the middle lower reaches of Yangtze River Valley in China. The results indicated that, in the process of growth, the content of soil alkali-hydrolyzable nitrogen in 0–60 cm soil layers of N0 treatment presented the trend of decreasing firstly and increasing then. While that of other treatments decreased firstly, increased after topdressing, decreased again, and increased after the beginning of boll opening. Soil available phosphorus and available potassium in 0–60 cm soil layers at two experimental locations presented the similar trends of decreasing firstly and increasing then. Soil available nutrient in 0–60 cm soil layers decreased with the deepening of the layer. Soil alkali-hydrolyzable nitrogen and available phosphorus in the same soil layer of N1, N2, N3, and N4 treatments in Nanjing presented the similar decreasing as the horizontal distance to cotton plant increased, and in N0 treatment, there was no significant variation in alkali-hydrolyzable nitrogen and available phosphorus contents. The spatial and temporal variability for soil alkali-hydrolyzable nitrogen was more significant in Nanjing than in Anyang. While for soil available phosphorus, it was more significant in Anyang than in Nanjing. Soil available potassium in 0–60 cm soil layers in Nanjing and in 20–60 cm soil layers in Anyang presented the similar decreasing with the increasing of horizontal distance to cotton plant, while that in 0–20 cm soil layers in Anyang increasing. As a result, at the nitrogen application level of 360 kg ha^-1 for Anyang and 240 kg ha^-1 for Nanjing, yield components were the relatively optimal, yield was the maximum and the fiber quality of length and strength was better. So, in order to increase lint yield and fiber quality, different ecological regions should follow the spatial and temporal variability of soil available nutrient in cotton field at flower and boll stage to confirm the optimal fertilizer level.