棉花SPAD值推荐施氮模型应用与修正

【目的】研究棉花SPAD值推荐施氮模型应用与修正,为棉花SPAD法推荐施肥模型在田间应用的准确性、普适性及合理性提供科学依据。【方法】采用田间小区试验,设3个处理:按照棉花生育时期测定SPAD值推荐施氮(N₁);按照棉花叶龄测定SPAD值推荐施氮(N₂);按当地高产模式推荐施氮(N₃);对比SPAD值、产量构成指标等数据变化特征,修正SPAD值推荐施氮模型。【结果】N₁处理与SPAD值关系式为y=0.090 3x+46.618, R²=0.855;N₂处理与SPAD值关系式为y=0.108 6x+48.666,R²=0.765,N₁处理的追氮量与SPAD值的相关性要高于N₂处理;M₁推荐的N₁处理追氮量与M₂推荐的N₂处理追氮量对产量的影响差异不显著;N₁的追氮量417.45 kg/hm²高于当地高产的追氮量,N₂的285.40 kg/hm²低于当地高产的追氮量,但是N₁和N₂的产量均明显低于当地高产产量;在棉花各个生育时期,N₁与N₂的追肥量与棉花需肥量趋势基本一致,但是各时期N₁的追肥量高于N₂的追肥量。【结论】棉花SPAD值推荐施氮模型具有科学性、可应用性,但在土壤、气候、管理模式变化时需要对模型参数进行修正,才能达到SPAD值与施氮量的最大相关性。修正SPAD值推荐施氮模型时可以利用原有模型的推荐施肥量、当地多年高产施肥量,通过反推快速得到当年就能使用的新推荐施肥公式。

Application and Modification of Recommended Nitrogen Application Model for SPAD Value of Cotton

【Objective】 The purpose of the thesis is to provide scientific basis for the accuracy, universality and rationality of applying cotton SPAD method recommended fertilization model.【Methods】 This thesis establishes three treatments through field plot experiment: Determine recommended nitrogen application (N₁) based on the SPAD value of cotton growth period; Determine recommended nitrogen application (N₂) in line with the SPAD value of cotton leaf age (N₂); Carry out recommended nitrogen application (N₃) by following the local high yield model.The recommended nitrogen application model of SPAD value is modified through observing and comparing the variation features of SPAD value, yield composition index and so on.【Results】 It is y=0.090,3x+46.618, R²=0.855 for the correlation between N₁ treatment and SPAD value; and is y=0.108,6x+48.666, R²=0.765 for the correlation between N₂ treatment and SPAD value, in which the correlation between nitrogen recovery and SPAD value of N₁ treatment was higher than that of N₂ treatment. No significant difference in the effect of nitrogen recovery amount on yield between the treatment of N₁ recommended by M₁ and the treatment of N₂ recommended by M₂; The nitrogen recovery amount 417.45 kg/hm² of of N₁ is higher than local high-yield nitrogen recovery amount, and the 285.40 kg/hm² of N₂ is lower than the local high-yield nitrogen recovery amount, while the yield of N₁ and N₂ is obviously lower than that of local high yield. During each growth period of cotton, the trend of topdressing of N₁ and N₂ is basically consistent with that of cotton, while the topdressing of N₁ is higher than that of N₂ in each period.【Conclusion】 It is scientific and applicable for the recommended nitrogen application model of cotton SPAD value, while it needs to modify the model parameters at the change of soil, climate and management mod to reach the maximum correlation between SPAD value and nitrogen application amount. It is able to quickly obtain the new formula of recommended fertilization that can be used in the current year by reverse deduction when modifying recommended nitrogen application model of SPAD value though the use of the recommended fertilization amount of the original model and the local high yield fertilization amount with many years.