Periods of weed interference in chickpea grown under different doses of nitrogen fertilizer topdressing

ABSTRACT. Weed interference can reduce chickpea growth and, therefore, productivity depending on the period of coexistence and the nutritional status of the crop, among other factors. A study was performed over two crop years to estimate the critical period of weed interference (CPWI) during chickpea production under three doses of nitrogen (N) fertilizer topdressing (0, 50, and 75 kg N ha-1). The experiments were conducted at 0, 7, 14, 21, 28, 35, 42, 56, 63, and 140 days after emergence (DAE) of chickpea/weed coexistence under two conditions: initially weed-free and initially weed-infested. The presence of weeds negatively affected chickpea production and reduced yields by 70% on average regardless of N rate, rendering the crop economically unfeasible. The CPWI ranged from 5 to 76 DAE and was not affected by N topdressing up to 75 kg N ha-1 in both crop years, assuming an acceptable production loss of 5%. Although the CPWI without fertilization (0 kg N ha-1) was similar to that when fertilized with 50 and 75 kg N ha-1, the two topdressing doses increased chickpea productivity by 37% and 51%, on average, respectively.

摘要。杂草干扰会抑制鹰嘴豆生长，进而降低其产量，影响程度取决于杂草与作物的共生时长、作物营养状况等诸多因素。本研究在两个种植季内开展，旨在明确三种氮肥追肥用量（0、50、75 kg N·ha⁻¹）下，鹰嘴豆种植过程中的杂草干扰临界期（critical period of weed interference, CPWI）。本试验设置两种处理条件：初始无杂草组与初始有杂草组，分别在鹰嘴豆与杂草共生后的0、7、14、21、28、35、42、56、63及140个出苗后天数（days after emergence, DAE）节点实施。无论氮肥施用量如何，杂草的存在均会对鹰嘴豆生产产生负面影响，平均减产幅度达70%，致使该作物种植失去经济可行性。以5%的可接受产量损失为判定阈值时，两个种植季内的杂草干扰临界期均介于5~76 DAE之间，且不受75 kg N·ha⁻¹以内的氮肥追肥用量影响。尽管不施肥组（0 kg N·ha⁻¹）的杂草干扰临界期与50、75 kg N·ha⁻¹施肥组无显著差异，但两种追肥用量分别使鹰嘴豆产量平均提升37%和51%。