氮肥减施与追氮技术对甜荞生理特性的影响

Effect of reduced nitrogen fertilization and nitrogen topdressing on physiological traits of buckwheat

【目的】研究氮肥减施与追氮方式对甜荞生物量、光合特性及抗氧化系统的影响,为甜荞增产增效提供理论依据。【方法】以甜荞为供试作物,设置6个氮肥施用处理:CK1(基肥:100kg/hm^(2) N)、CK2(基肥+土壤追肥:70 kg/hm^(2) N+30 kg/hm^(2) N)、CK3(基肥+人工喷施:70 kg/hm^(2) N+1%浓度尿素溶液(0.25 kg/hm^(2) N))、T4(基肥+无人机喷施:70 kg/hm^(2) N+1%浓度尿素溶液(0.25 kg/hm^(2) N))、T5(基肥+无人机喷施:70 kg/hm^(2) N+2%浓度尿素溶液(0.5 kg/hm^(2) N))、T6(基肥+无人机喷施:70 kg/hm^(2) N+4%浓度尿素溶液(1 kg/hm^(2) N)),探索不同施氮方式对甜荞干物质积累量、光合特性及抗氧化酶活性的影响。【结果】甜荞地上部干物质积累量随生育期推进逐渐增加,地上部干物质积累速率随生育期推进呈先升后降的趋势,T5处理下的成熟期地上部干物质积累量及积累速率较其他处理提高16.03%~82.88%和34.05%~132.05%。在甜荞成熟期,不同处理下的甜荞叶片的叶绿素量和净光合速率存在显著差异,T5处理最高,T4处理次之,CK1最小。甜荞抗氧化酶活性呈单峰曲线变化规律,盛花期后T5处理下的抗氧化酶活性高于其他处理,成熟期T5处理较其他处理的超氧化物歧化酶活性提高1.16%~19.16%,过氧化物酶活性提高0.49%~35.49%,过氧化氢酶活性提高1.34%~51.76%。各处理甜荞叶片丙二醛量均随叶片衰老呈逐渐增加趋势,至成熟期T4处理和T5处理下的丙二醛量相同,较其他处理降低了10.99%~19.00%。T5处理对甜荞单株粒数、单株粒质量和千粒质量均有促进作用,较其他处理分别增加9.65%~80.67%、5.15%~59.17%和9.77%~17.01%,且该处理下的甜荞产量达到最大,较其他处理提高21.66%~140.30%。【结论】基肥70 kg/hm^(2) N+无人机叶面喷施1%~2%浓度尿素溶液有利于甜荞生长,可显著增加甜荞地上干物质积累量及抗氧化酶活性,延长叶片功能期,从而提高甜荞生育中后期的光合速率,最终提高产量。

【Objective】Overuse of nitrogen fertilizer is a major source of nonpoint pollution in agricultural production.Reducing nitrogen application and improving nitrogen use efficiency are essential for developing sustainable agriculture.We investigate in this paper the impact of reduced nitrogen fertilization and nitrogen topdressing on physiological traits of buckwheat.【Method】The field experiment consisted of six nitrogen fertilizations:applying 100 kg/hm^(2) of nitrogen as base fertilizer(CK1),applying 70 kg/hm^(2) of nitrogen as base fertilizer and 30 kg/hm^(2) of nitrogen for topdressing(CK2),applying 70 kg/hm^(2) of nitrogen as base fertilizer and 0.25 kg/hm^(2) of nitrogen in dissolved urea(concentration 1%)for spray-topdressing(CK3),applying 70 kg/hm^(2) of nitrogen as base fertilizer and 0.25 kg/hm^(2) of nitrogen in dissolved urea(1%concentration)for spray-topdressing using UAV(T4),applying 70 kg/hm^(2) of nitrogen as base fertilizer and 0.5 kg/hm^(2) of nitrogen in dissolved urea(concentration 2%)for spray-topdressing using UAV(T5),applying 70 kg/hm^(2) of nitrogen as base fertilizer and 1 kg/hm^(2) of nitrogen in dissolved urea(concentration 4%)for spray-topdressing using UAV(T5).In each treatment,we measured dry matter accumulation,photosynthetic traits,and antioxidant enzyme activity of the crop.【Result】①Aboveground dry matter accumulation increased over time,with the accumulation rate initially increasing and then declining.At the maturity stage,T5 had the highest dry matter accumulation,surpassing other treatments by 16.03%-82.88%in total accumulation and 34.05%-132.05%in accumulation rate.②Chlorophyll content and net photosynthetic rate varied with treatments,with T5 showing the highest values at maturity stage and CK1 the lowest.③Antioxidant enzyme activity exhibited a single-peak trend as the crop matured.At the post-bloom stage,T5 increased superoxide dismutase activity by 1.16%-19.16%,peroxidase activity by 0.49%-35.49%,and catalase activity by 11.89%-51.76%,compared to other treatments,while antioxidant activity in T4 and T5 was comparable.Malondialdehyde content increased with leaf senescence,but their values in T4 and T5 were similar at the maturity stage,10.99%-19.00%lower than that in other treatments.④Compared to other treatments,T5 significantly increased grain number,grain weight per plant,and 1000-grain weight by 9.65%-80.67%,5.15%-59.17%,and 9.77%-17.01%,respectively,resulting in a yield increase of 21.66%-140.30%.【Conclusion】Applying 70 kg/hm^(2) of nitrogen as a basal fertilizer combined with a 1%-2%urea solution applied via UAV for foliar spraying is the optimal nitrogen fertilization strategy for buckwheat;it increases dry matter accumulation,enhances antioxidant enzyme activity,prolonges leaf functionality,and improvs photosynthetic efficiency,thereby boosting crop yield.