Morpho-physiological and productive biometry in semi-erect cultivars of the cowpea under different plant populations

Antônio Aécio De Carvalho Bezerra,Lucélia De Cássia Rodrigues De Brito,Maurisrael De Moura Rocha,Adão Cabral Das Neves

doi:10.5935/1806-6690.20170072

Antônio Aécio De Carvalho Bezerra, Lucélia De Cássia Rodrigues De Brito + Show 2 more

Open Access

https://doi.org/10.5935/1806-6690.20170072

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Abstract

The aim of this study was to evaluate morpho-physiological and productive characteristics in four semi-erect cultivars of the cowpea under five plant populations. The experiment was conducted in the experimental area of Embrapa Meio-Norte in Teresina in the State of Piaui, Brazil (PI). The experimental design was of randomised complete blocks with four replications, in a 4 x 5 factorial scheme, for evaluating four cultivars (BRS Guariba, BRS Novaera, BRS Potengi and BRS Tumucumaque) and five plant populations (105, 2x105, 3x105, 4x105 and 5x105 plants ha-1). There were significant differences between cultivars for primary branch length (PBL), number of lateral branches (NLB), 100-grain weight (HGW), and dry-grain yield (GY). The maximum PBL of 58.5 cm was obtained with 300 thousand plants ha-1, corresponding to an increase of 11.5% when compared to 100 thousand plants ha-1. However, there was a reduction of 91.2% in NLB when compared to the populations of 100 and 500 thousand plants ha-1. The increases of 188% obtained in the leaf area index (LAI) in the range of 100 to 500 thousand plants ha-1 explain the linear increase in the crop growth rate (CGR) as being due to the greater production of leaf area; also, the decreases seen in the net assimilation rate (NAR), especially in the range of 100 to 300 thousand plants ha-1, are explained as due to the consequent self-shading, which was intensified in the larger populations. LAI, light interception, and CGR in the cultivars increase in response to higher densities. HGW and GY are not significantly affected by the different populations.

Highlights

The cowpea [Vigna unguiculata (L.) Walp], due to its nutritional potential together with its ease of production and accessibility, is the most important food legume, especially for populations in the north and northeast of Brazil, which have been characterised historically by protein-energy and mineral deficiencies (BEZERRA et al, 2014).Modern cultivars, with a higher potential for grain yield and responsive to cropping technology, have helped expand the cowpea to areas of the Cerrado and the Central-West region, as the main or off-season crop
The increases of 188% obtained in the leaf area index (LAI) in the range of 100 to 500 thousand plants ha-1 explain the linear increase in the crop growth rate (CGR) as being due to the greater production of leaf area; the decreases seen in the net assimilation rate (NAR), especially in the range of 100 to 300 thousand plants ha-1, are explained as due to the consequent self-shading, which was intensified in the larger populations
Expression of the production potential of the crop depends on the favourable combination of a set of factors, noteworthy among them being population density, which directly influences the use of technological, environmental and management resources

Summary

Introduction

The cowpea [Vigna unguiculata (L.) Walp], due to its nutritional potential together with its ease of production and accessibility, is the most important food legume, especially for populations in the north and northeast of Brazil, which have been characterised historically by protein-energy and mineral deficiencies (BEZERRA et al, 2014).Modern cultivars, with a higher potential for grain yield and responsive to cropping technology, have helped expand the cowpea to areas of the Cerrado and the Central-West region, as the main or off-season crop. The cowpea [Vigna unguiculata (L.) Walp], due to its nutritional potential together with its ease of production and accessibility, is the most important food legume, especially for populations in the north and northeast of Brazil, which have been characterised historically by protein-energy and mineral deficiencies (BEZERRA et al, 2014). Expression of the production potential of the crop depends on the favourable combination of a set of factors, noteworthy among them being population density, which directly influences the use of technological, environmental and management resources. According to Oroka and Omoregie (2007), sufficient increases in the population density of the cowpea can significantly enhance the interception of solar radiation and efficiency in its use. Mendes et al (2005), working with cowpea, found that the percentage of intercepted light and the leaf area index increased by 50% and 206.5% respectively, comparing populations of from 41,666 to 166,666 plants ha-1

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