基于NDVI的滴灌春小麦氮肥分期施用推荐模型

为探讨利用冠层光谱数据实现滴灌春小麦推荐追施氮肥的可行性,利用手持主动遥感光谱仪(Greenseeker)测定了滴灌春小麦各生育时期的冠层NDVI值,分析其与滴灌小麦不同时期追施氮肥效应的关系.结果表明,从拔节期到乳熟期NDVI值与春小麦出苗后天数可用一元二次函数拟合,模型精度较高,R2均大于0.91;拔节期、孕穗期、抽穗期和灌浆期的冠层NDVI值与施氮量之间呈极显著线性相关;利用一元二次模型拟合出施氮量与产量之间的关系,得出实现最高产量7 393 kg·hm-2下的施氮量为289kg·hm-2,实现最佳经济产量7 378 kg·hm-2下的施氮量为265 kg·hm-2;拔节期、孕穗期、抽穗期和灌浆期的NDVI临界值分别为0.715、0.792、0.887和0.911;根据各生育时期NDVI值与施氮量的关系,建立了氮肥推荐模型,并且根据模型计算出滴灌春小麦各生育时期NDVI值对应的氮肥追施推荐用量表.

Nitrogenous Fertilizer Recommendation Model Based on NDVI for Drip-irrigated Spring Wheat

Nitrogenous fertilizer recommendation for drip-irrigated spring wheat was explored based on the NDVI of wheat canopy measured at different growth stages using Greenseeker hand-held spectrometer. The results showed that the relationship between NDVI and days after emergence during Jointing stage and Milking stage fitted with a quadratic equation. The model accuracy was high with R >0.91. A significant linear correlation was observed for nitrogen rate and NDVI at Jointing, booting, heating and filling stages. The highest predicted yield was 7 393 kg·hm^-2, corresponding to the optimal nitrogenous fertilizer rate of 289 kg·hm^-2 under the experiment management scenario. The most profitable yield was 7 378 kg·hm^-2 and the N rate was 265 kg·hm^-2. The critical NDVI at jointing, booting, heating and filling stages was 0.715, 0.792, 0.887 and 0.911,respectively.The nitrogenous fertilizer recommendation model was evaluated based on the relationship between NDVI and nitrogen application amount at different growth stages. N fertilizer recommendation form was built by the model.