灌溉和施氮策略对滴灌施肥棉花蕾铃脱落的影响

通过田间小区试验,研究了2种滴灌施氮策略(氮磷钾肥全部滴施、氮肥滴施磷钾肥基施)下3个灌溉定额(3 300、3 900、4 500 m3/hm~2)和4个施氮水平(150、225、300、375 kg/hm~2)对膜下滴灌棉花蕾铃脱落的影响。结果表明,2种施氮策略下,随生育期延长,棉花蕾铃脱落率逐渐增加,花铃盛期达到最高,花铃后期迅速降低。不同灌溉定额下,在中灌溉定额(3 900 m3/hm~2)下蕾铃脱落率最低;不同施氮处理条件下,低氮用量(150 kg/hm~2)时蕾铃脱落率显著增加,施氮量300 kg/hm~2时蕾铃脱落率均较低;灌溉定额和施氮量过低或过高均会造成蕾铃脱落率显著增加。在氮磷钾肥全部滴施的施氮策略下,理论上灌溉定额3 890.46 m3/hm~2、施氮量291.25 kg/hm~2时蕾铃脱落率可降至53.60%;氮肥滴施磷钾肥基施的施氮策略下,理论上灌溉定额3 805.24 m3/hm~2、施氮量288.76 kg/hm~2时蕾铃脱落率可降至49.12%。总体上,氮肥滴施磷钾肥基施施氮策略较氮磷钾肥全部滴施施氮策略具有较低的蕾铃脱落率。

Application Schedule of N-P-K in Drip Fertigation Affects Abscission of Cotton Bolls

This paper presents the results of a field experiment aiming to investigate the impact of different drip fertigation schedules on abscission of cotton bolls.We considered three irrigation amounts,3 300,3 900 and 4 500 m3/hm2,and four N application rates,150,225,300,375 kg/hm2.The N was either applied with P-K as topdressing fertilizer,or applied as topdressing with the drip irrigation while the P-K were used as base fertilizer.The results showed that the boll abscission increased first,peaking at the boll setting stage,and then decreased rapidly at the flowering stage under both N application methods.The abscission rate atirrigation of 3 900 m3/hm2 was the lowest in comparison with others.When the N application was 150 kg/hm2,the abscission rate of the cotton buds and bolls increased significantly under different N applications.The abscission was the lowest when N application was 300 kg/hm2,increasing when the irrigation amount and nitrogen application were either too low or too high.When N was applied with P-K as topdressing fertilizer at the rate of 291.25 kg/hm2 and the irrigation amount was 3 890.46 m3/hm2,the boll abscission was 53.60％,while trnder the same water and N applications,applying N-P-K as topdressing with the drip irrigation decreased the abscission by 49.12％.In summary,applying N with P-K as topdressing was more efficient in reducing the abscission compared with applying N together with the drip irrigation by using P-K as base fertilizer.