PDF(Pubmed)
Abstract：
Sowing date and soil fertility are very important factors in the overwintering and production performance of alfalfa (Medicago sativa L.), yet there\'s a knowledge gap in knowledge on how late-seeded alfalfa responds to phosphorus (P) fertilization. A field study was conducted in Inner Mongolia from 2020 to 2022 using a split-plot design. The main plots consisted of five sowing dates (31 July, 8, 16, and 24 August, and 1 September), while the subplots involved five P application rates (0, 40, 70, 100, and 130 kg P2O5 ha-1). Throughout the growing seasons, the overwintering rate, root traits, forage yield, and yield components were measured. The results revealed a consistent decrease in overwintering ability and productivity with the delayed sowing. This reduction in overwintering rate was mainly due to diminished root traits, while the decrease in forage yield was largely associated with a reduction in plants per square meter. However, P fertilizer application to late-seeded alfalfa demonstrated potential in enhancing the diameter of both the crown and taproot, thus strengthening the root system and improving the overwintering rate, the rate of increase ranges from 11.6 to 49%. This adjustment could also improve the shoots per square meter and mass per shoot, increasing by 9.4-31.3% and 15.0-27.1% respectively in 2 years, which can offset the decline in forage yield caused by late sowing and might even increase the forage yield. Regression and path analysis indicated that alfalfa forage yield is primarily affected by mass per shoot rather than shoots per square meter. This study recommended that the sowing of alfalfa in similar regions of Inner Mongolia should not be later than mid-August. Moreover, applying P fertilizer (P2O5) at 70.6-85.9 kg ha-1 can enhance the forage yield and persistence of late-seeded alfalfa. Therefore, appropriate late sowing combined with the application of P fertilizer can be used as an efficient cultivation strategy for alfalfa cultivation after a short-season crop harvest in arid and cold regions.
摘要：
播期和土壤肥力是影响紫花苜蓿越冬和生产性能的重要因素,然而，关于晚种苜蓿如何响应磷（P）施肥的知识存在知识差距。于2020年至2022年在内蒙古采用分块设计进行了实地研究。主要地块包括五个播种日期(7月31日，8月16日和24日，和9月1日)，而子图涉及五个磷的施用量（0、40、70、100和130kgP2O5ha-1）。在整个生长季节，越冬率，根性状，牧草产量，和产量组分进行了测量。结果表明，随着播种的延迟，越冬能力和生产力持续下降。越冬率的降低主要是由于根系性状的减少，而牧草产量的下降在很大程度上与每平方米植物的减少有关。然而,对晚种苜蓿施用磷肥显示出增强冠部和主根直径的潜力，从而加强根系，提高越冬率，增长率从11.6%到49%不等。这种调整还可以提高每平方米的拍摄和每次拍摄的质量，两年内分别增长9.4-31.3％和15.0-27.1％，这可以抵消晚播导致的牧草产量下降，甚至可能增加牧草产量。回归和通径分析表明，紫花苜蓿的牧草产量主要受每枝质量的影响，而不是每平方米的枝条。本研究建议内蒙古同类地区苜蓿播种时间不宜晚于8月中旬。此外，以70.6-85.9kgha-1施用磷肥（P2O5）可以提高晚播苜蓿的牧草产量和持久性。因此,在干旱和寒冷地区，短季收获后，适当的晚播结合施用磷肥可作为苜蓿栽培的有效栽培策略。
