Radiation Use Efficiency for Cowpea Subjected to Different Irrigation Depths Under the Climatic Conditions of the Northeast Of Pará State

• Main Authors: Denis de Pinho Sousa, Paulo Jorge Oliveira Ponte de Souza, Vivian Dielly da Silva Farias, Hildo Giuseppe Caldas Nunes, Denílson Pontes Ferreira, João Vitor Pinto Novoa, Marcus José Alves de Lima
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Meteorologia
• Series: Revista Brasileira de Meteorologia
• Subjects: vigna unguiculata; radiação interceptada; coeficiente de extinção; déficit hídrico
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-77862018000400579&lng=en&tlng=en

Abstract This study aims to determine the cowpea efficiency in absorbing and using solar radiation according to different irrigation depths under the climatic conditions of the northeast of Pará State. The experiment was carried out on 2014 and 2016 in an experimental design of randomized blocks, which consisted in six blocks with four treatments, in which different irrigation depths the reproductive phase were applied, as follows: T100, T50, T25 e T0, that corresponded to 100%, 50%, 25% e 0% of the crop evapotranspiration, respectively. The absorbed photosynthetically active radiation, leaf area index (LAI), total aerial dry matter (TADM) and grain yield were measured. The extinction coefficient (k) was obtained by nonlinear regression between the fraction of absorbed PAR (fPARinter) and the LAI. The radiation use efficiency (RUE) was calculated by linear regression between the TADM and the accumulated absorbed PAR. The water deficit imposed by the treatments had a significant influence on the LAI, TADM and cowpea yields. The water deficit did not significantly influenced k – it ranged between 0.83 for T100 and 0.70 for T0. The RUE showed significant behaviors regarding the treatments with adequate water supply and treatments under water deficit, ranging from 2.23 to 1.64 g·MJ-1, respectively.