Weed interference periods in cowpea crop

ABSTRACT Cowpea is one of the pulse crops that present the highest potential for growing in the Semiarid region of Brazil. Lowcost vegetable protein source, it has resilience to adverse conditions, however, in competition with weeds, its productivity can be strongly compromised. To overcoming this situation, it is essential for integrated management programs to determine the critical period for preventing interference. Thus, the objective of this work was to determine weed interference periods and the effect of coexistence periods on cowpea grain yield in the Semiarid region of the state of Minas Gerais, Brazil. The treatments were arranged in a 2×9 factorial scheme, as follows: cultivation in coexistence with weeds and cultivation under weed control, for nine crescent periods (0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56 and 0-63 days after crop emergence), in a randomized experimental block design with four replications. The weed community was studied through phytosociological survey and evaluation of dry matter production and cowpea was evaluated for dry matter production, 100-grain mass and grain yield. The interference periods were determined using a non-linear logistic regression model. The weed community found was composed of 70% dicotyledonous and 30% monocotyledon plants, distributed in seven families and ten species. The coexistence with weeds results in losses of up to 90% in cowpea grain yield. The critical period of weed control in cowpea crop in the Semiarid region of the state of Minas Gerais, Brazil, is 11 to 36 days after crop emergence.摘要 豇豆（cowpea）是巴西半干旱地区最具种植潜力的食用豆作物之一。作为低成本植物蛋白来源，其对逆境胁迫具有较强耐受性，但在与杂草竞争时，籽粒产量会受到显著影响。为应对这一问题，制定杂草综合防控方案需明确杂草干扰临界期。因此，本研究旨在明确巴西米纳斯吉拉斯州（Minas Gerais）半干旱地区杂草对豇豆的干扰时长，以及杂草共存期对豇豆籽粒产量的影响。 试验采用2×9因子设计，设置两种栽培模式：与杂草共存栽培、杂草防控栽培，搭配9个递增时长区间（作物出苗后0~7、0~14、0~21、0~28、0~35、0~42、0~49、0~56及0~63天），并采用随机区组设计，设置4次重复。 通过植物社会学调查对杂草群落进行研究，并测定杂草干物质产量；同时对豇豆的干物质产量、百粒重及籽粒产量进行测定。本研究采用非线性逻辑回归模型确定杂草干扰临界期。 本次调查发现的杂草群落由70%双子叶植物与30%单子叶植物组成，隶属于7个科共10个物种。与杂草共存会导致豇豆籽粒产量最高损失达90%。在巴西米纳斯吉拉斯州半干旱地区，豇豆田杂草防控临界期为作物出苗后11~36天。