不同磷敏感棉花品种临界磷浓度稀释模型与磷营养诊断

Critical Phosphorus Concentration Dilution Model and Phosphorus Nutrition Diagnosis in Two Cotton Cultivars with Different Phosphorus Sensitivity

【目的】建立不同磷敏感性棉花品种临界磷浓度稀释模型,并基于模型确定磷营养指数,为实现棉花合理施用磷肥提供理论依据。【方法】以磷敏感型棉花品种鲁54和磷弱敏感型品种豫早棉9110为试验材料,于2017—2018年在江苏省大丰市稻麦原种场设置施磷量(0、50、100、150、200 kg P2O5·hm-2)试验,分析施磷量对棉花干物质累积、磷浓度动态变化和籽棉产量及产量构成的影响。利用2017年棉花地上部生物量和磷浓度数据分别建立2个品种临界磷浓度稀释模型,确定磷营养指数(phosphorus nutrition index,PNI)。利用2018年数据对模型进行验证,并通过2年数据研究磷营养指数和相对地上部生物量之间的关系。【结果】施磷量对铃重没有显著影响,但150、200 kg P2O5·hm-2施磷量下棉花铃数和籽棉产量显著增加。随施磷量的增加,磷敏感型棉花品种鲁54铃数增加幅度为16.0%—37.9%,籽棉产量增加幅度为16.6%—44.9%,均分别高于磷弱敏感性棉花品种豫早棉9110铃数(6.3%—32.6%)和籽棉产量(6.6%—35.6%)的增加幅度。随生育进程的推进,棉花地上部磷浓度逐渐降低,地上部生物量呈升高趋势。在各取样时期,棉花地上部生物量、磷浓度均随施磷量的增加而升高,表现为0<50<100<150≈200 kg P2O5·hm-2。根据2017年地上部生物量和磷浓度的关系,分别建立了2个品种的临界磷稀释曲线模型(鲁54:Pc=0.784W-0.221,豫早棉9110:Pc=0.774W-0.198)。2个稀释曲线模型的RMSE分别为0.1296、0.1383;n-RMSE分别为17.8504%、18.5447%,说明模型有较好的稳定性,且鲁54的模型稳定性略高于豫早棉9110。与豫早棉9110的模型参数相比,鲁54的参数a、b分别提高了1.29%、11.62%。基于临界磷浓度稀释曲线的PNI随生育进程的推移先升高后下降,在同一取样时期,PNI随施磷量的增加而升高。PNI与相对地上部生物量显著正相关。【结论】施磷对铃重没有显著影响,但显著提高棉花铃数,进而提高了棉花籽棉产量。磷敏感棉花品种鲁54每积累单位干物质时磷浓度下降速度大于豫早棉9110。棉花临界磷浓度稀释曲线和PNI可以很好地诊断和评价棉株磷素营养状况。综合考虑棉花籽棉产量及PNI,150 kg P2O5·hm-2的施磷量为本地区棉花适宜施磷量。

【Objective】In order to provide a theoretical basis for optimum application of phosphorus fertilizer in cotton, the critical phosphorus concentration(CPC) dilution curve of two cotton cultivars with different phosphorus sensitivity and calculated phosphorus nutrition index(PNI) were established and compared. 【Method】In 2017 and 2018, the field experiments with five phosphorus(P) levels(0, 50, 100, 150, and 200 kg P2 O5·hm-2) were conducted by `using two cotton cultivars with different phosphorus sensitivity, Lu 54 and Yuzaomian 9110, at Dafeng, Jiangsu province.【Result】Phosphorus application had no significant effect on cotton boll weight, but the application of 150 and 200 kg P2 O5·hm-2 significantly increased cotton boll number and seedcotton yield. With phosphorus application increasing, cotton boll number and seedcotton yield of phosphorus sensitive cotton variety(Lu 54) were increased by 16.0%-37.9% and 16.6%-44.9%, respectively, which was higher than the increase of Yuzaomian 9110. Cotton biomass increased while phosphorus concentration decreased as cotton plant growing under all P treatments. At the same sampling day, cotton shoot biomass and phosphorus concentration raised with the phosphorus application increasing and peaked at 150 and 200 kg P2 O5·hm-2. Based on the relationship between the shoot biomass and phosphorus concentration in 2017, the critical phosphorus dilution curve models for the two varieties were established(Lu 54: Pc=0.784 W-0.221;Yuzaomian 9110: Pc=0.774 W-0.198). The RMSE of the two dilution curve models were 0.1296 and 0.1383, and the n-RMSE were 17.8504% and 18.5447%, respectively, indicating that the model was stability, and the stability of Lu 54 was slightly higher than that of Yuzaomian 9110. Compared with the model parameters of Yuzaomian 9110, parameter a and b of Lu 54 was increased by 1.29% and 11.62%, respectively. PNI increased and then decreased with the growth process, and augmented with the increase of phosphorus application at the same sampling day. PNI was also positively correlated with relative aboveground biomass. 【Conclusion】 Phosphorus application had no significant effects on cotton boll weight, but significantly increased boll number, and consequently increased seedcotton yield. Phosphorus-sensitive variety Lu 54 had a faster decline in phosphorus concentration per unit of dry matter accumulation than Yuzaomian 9110. CPC and PNI of two cotton varieties could diagnose and evaluate the phosphorus nutrition status of cotton plants. According to the results of seedcotton yield and PNI, the application of 150 kg·hm-2 phosphorus fertilizer was suitable for cotton in this region.