Agronomic performance of 'BRS' Itaim cowpea beans at different planting densities under no-tillage and conventional systems

<div><p>ABSTRACT Cowpea beans play an important role in Brazilian farming, mainly in northern and northeastern regions, where it is widely grown among smallholder farmers. In recent years, commercial farmers have expanded its cultivation, mostly to the Midwest. This study aimed at evaluating the planting density of 'BRS Itaim' black-eyed cowpea beans under conventional (CT) and no-tillage (NT), with 75% mulch in the first year. Two experiments (CT and NT) were conducted at Embrapa Meio-Norte in Teresina - PI (Brazil), during the 2014/2015 harvest. Both experiments were carried out in a randomized block design with four replicates, considering the planting densities (PD) 12, 16, 20, 24, and 28 plants m-2. In both systems, grain yields (GY) and the number of pods per unit area (NPA) responded quadratically to an increase in PD, while a linear decreasing response was observed for the number of pods per unit area. The maximum grain yields (GY) were 1,492 kg ha-1 (23.8 plants m-2) and 1,136 kg ha-1 (23.2 plants m-2) under CT and NT, respectively. The NPA was most correlated with GY, presenting a value of 0.74 (. <0.01). The survival rate of cowpea seedlings was 94% under CT and 88% under NT. This larger reduction under NT might be attributed to a higher incidence of fungi in the soil under this system (e.g. Furasium solani, Fusarium oxysporum, Macrophomina phaseolina, Pythium spp, Sclerotium rolfsii and Rhizoctonia solani).</p></div

Agronomic performance of the cowpea under different irrigation depths and row spacing

<div><p>ABSTRACT The cowpea is of great socioeconomic importance in the North, Northeast and Mid-West of Brazil, and its irrigated farming has recently been on the increase in these regions. The aim of this study was to evaluate the agronomic performance of the cowpea 'BRS Tumucumaque' for different row spacings and irrigation depths, under the conditions of soil and climate of Teresina, in the State of Piauí. The experiment was carried out from August to November 2014, in a Yellow Argisol at the Experimental Area of Embrapa Meio-Norte in Teresina. The experimental design was of randomised blocks in subdivided lots, with four replications. The treatments consisted of five irrigation depths (40% ETo, 70% ETo, 100% ETo, 130% ETo and 160% ETo) in the main plot, and four spacings between rows (0.36 m, 0.45 m, 0.60 m and 0.90 m) in the sub-lots. Leaf area index, pod length, number of grains per pod, number of pods per plant and grain productivity were evaluated. There was significant interaction (. <0.01) between irrigation depth and row spacing for grain productivity only. There was a significant increasing linear effect (. <0.01) from irrigation depth on pod length, number of pods per plant and number of grains per pod. The larger irrigation depths at the smaller row spacings give the greatest grain productivity. With leaf area index, there was a significant effect from irrigation depth and row spacing for the periods under evaluation.</p></div