不同降雨年型磷肥对旱地小麦根系特征、磷素吸收利用和产量的影响

Effects of phosphorus fertilizer on root characteristics,uptake and utilization of phosphorus and yield of dryland wheat with contrasting yearly rainfall pattern

为了明确旱地小麦生育特性、养分运转对磷肥的响应机制,探索不同降雨年型旱地小麦磷肥施用技术,于2012—2016年在山西农业大学旱地小麦试验示范基地开展大田试验,研究不同降雨年型中4个施磷量(0、75、150和225 kg·hm^(-2))对旱地小麦根系生长、产量形成和磷肥利用的影响。结果表明:与不施磷相比,施磷可以显著增加旱地小麦拔节、开花和成熟期0~80 cm根重密度和各生育时期根表面积;提高拔节-开花期、开花-成熟期土壤耗水量和总耗水量,以及花前磷素运转量和籽粒磷素积累量;穗数和产量分别增加9.2%~22.5%和11.8%~30.0%,水分利用效率提高2.1%~12.1%。在欠水年,施磷量150和225 kg·hm^(-2)较75 kg·hm^(-2)可以显著增加各生育时期的根重密度和根表面积;显著增加播种-拔节期、拔节-开花期土壤耗水量和生育期总耗水量,分别为7.3~8.7、15.6~18.1和25.5~30.2 mm;显著增加花前磷素运转量和籽粒磷素积累量,最终显著增加穗数和产量,增幅分别为9.3%~10.7%和11.9%~14.6%;施磷量为150 kg·hm^(-2)的磷肥利用效率显著高于其他处理,增幅为20%~82%。在平水年,施磷量150和225 kg·hm^(-2)较75 kg·hm^(-2)可以增加开花、成熟期的根重密度和根表面积,以及开花-成熟期土壤耗水量和生育期总耗水量,分别为1.2~15.0和3.8~23.1 mm;增加花后磷素积累量和籽粒磷素积累量,最终增加穗数和产量,分别为1.4%~9.6%和3.5%~10.4%,且施磷量150 kg·hm^(-2)与75、225 kg·hm^(-2)差异显著。总之,磷肥主要促进了旱地小麦欠水年生育前、中期,平水年生育后期水分和养分的吸收能力,且主要通过提高穗数增加产量。本研究区以施磷量150 kg·hm^(-2)效果最佳,可统筹兼顾高产和水肥高效利用。

To understand the growth responses of dryland wheat to different application rates of phosphorus fertilizer in different rainfall years, we examined root characteristics, spike number, yield and phosphate utilization. Results would help improve phosphate fertilizer use in dryland wheat production. We carried out a field experiment at the research station of Shanxi Agricultural University from 2012 to 2016. We examined the effects of four application rates of phosphorus(0, 75, 150 and 225 kg·hm^(-2) on root growth, phosphate utilization and yield formation of dryland wheat in different years with contrasting rainfall pattern. Compared with the treatment without phosphorus fertilization, phosphate application increased root surface area at all growth stages and root weight density in the 0-80 cm soil layer at jointing, anthesis, and maturity stages. Phosphate application significantly increased soil water consumption from jointing to anthesis, and total soil water consumption in the growing season. Phosphate application enhanced the amount of pre-anthesis phosphate translocation and phosphate accumulation of grain. Spike number, yield and water use efficiency were increased with 75, 150 and 225 kg P·hm^(-2) by 9.2% to 22.5%, 11.8% to 30.0%, and 2.1% to 12.1%, respectively. In the dry years, the application rates of 150 and 225 kg P·hm^(-2) in comparison to 75 kg P·hm^(-2) significantly increased root weight density and root surface area at all stages, soil water consumption from sowing to jointing and from jointing to anthesis, and total water consumption in the growing season. In comparison to the rate of 75 kg P·hm^(-2), 150 and 225 kg P·hm^(-2) increased soil water consumption from sowing to jointing by 7.3-8.7 mm, soil water consumption from jointing to anthesis by 15.6-18.1 mm, and total water consumption by 15.6-18.1 mm. Significant increase in the pre-anthesis phosphate translocation and phosphate accumulation in grain was higher under 150 and 225 kg P·hm^(-2) than that under 75 kg P·hm^(-2) in dry years. Furthermore, the two rates(150 and 225 kg P·hm^(-2)) in dry years increased spike number by 9.3%-10.7% and yield by 11.9%-14.6%. The application rate of 150 kg P·hm^(-2) significantly improved phosphorus use efficiency by 20%-82% in comparison to other rates. In normal years, the rates of 150 and 225 kg P·hm^(-2) increased root surface area, root weight density at both anthesis and maturity compared with 75 kg P·hm^(-2). Soil water consumption from anthesis to maturity and total soil water consumption in the growing season were also increased by 1.2-15.0 and 3.8-23.1 mm, respectively. In addition, phosphorus accumulation in post-anthesis and phosphate accumulation in grain were increased in both 150 and 225 kg P·hm^(-2), which increased spike number by 1.4%-9.6% and yield by 3.5%-10.4%. The effects of phosphate application at the rate of 150 kg P·hm^(-2) were significantly different from 75 and 225 kg P·hm^(-2). In conclusion, phosphorus fertilizer application enhanced uptake of water and phosphate in dryland wheat at early and middle growth stages in dry years and at the late growth stage in normal years. Phosphorus application increased wheat yield mainly due to the increases of spike number. The application of 150 kg P·hm^(-2) is the best choice for high water and phosphorus fertilizer use efficiency and high yield in both dry and normal years.