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

Milton José Cardoso,Cândido Athayde Sobrinho,Francisco De Brito Melo,Edson Alves Bastos

doi:10.5935/1806-6690.20170101

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 (P<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).

Highlights

One of the major problems in cowpea cultivation regions, mainly in Northeastern and Northern Brazil, is related to rainfall unevenness together with other factors such as sandy soils, high temperatures, and inadequate management measures just as planting density, which contributes to a low yielding of grains, about 0.22 t ha-1 (CONAB, 2016)
It was a quadratic response to planting densities (PD) increase, which reached a maximum of 94.72 pods/ m-2 (CT with 22.27 plants/ m-2) and 64.68 pods/ m-2 (NT with 25.4 plants/ m-2). (Figure 3)
Under a no-tillage system with first year mulching, increasing plant densities cause a reduction in grain yield of ‘BRS Itaim’ cowpea beans as well as it favors soil fungi attack compared to a conventional tillage system; 2

Summary

Introduction

One of the major problems in cowpea cultivation regions, mainly in Northeastern and Northern Brazil, is related to rainfall unevenness together with other factors such as sandy soils, high temperatures, and inadequate management measures just as planting density, which contributes to a low yielding of grains, about 0.22 t ha-1 (CONAB, 2016). This values are much lower than those beans grown under a high-tech production system (BRACHTVOGEL et al, 2009; CARDOSO; RIBEIRO, 2006; MAKOI; CHIMPHANGO; DAKORA, 2009; MATOS FILHO et al, 2009; MENDES et al, 2007; NJOKU; MUONEKE, 2008; OLIVEIRA FILHO et al, 2016; OROKA; OMEREGIE, 2007). For BRS Novaera, Bezerra et al (2014) reported declines of 66.5% and 59.53% in NPP and GY, respectively. Naim, Jabereldar, and Mohamed (2011), while investigating the PDs of 6, 12, 18, and 24 kg ha-1, observed an increase in the number of grains per area, as well as reductions in NPP, 100-grain weight, GYP, and harvest index

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