Fenologia, produção e qualidade fisiológica de sementes crioulas de feijão-caupi produzidas com água salina

Abstract

The culture of cowpea (Vigna unguiculata (L.) Walp.) Plays a great socioeconomic and food importance in Brazil, mainly for family farmers in the northeastern region of the country. Irrigation is a technique of fundamental importance to guarantee the availability of water to plants, however, most of these are saline, which can intensify the salinization of soils, when poorly managed. In addition to irrigation, the identification of cowpea varieties tolerant to salinity can improve crop productivity in the edaphoclimatic conditions of the semiarid region, which represents a major step towards improving the quality of life of peasants. Thus, the objective was to evaluate the phenology, production and physiological quality of seeds of cowpea creole varieties submitted to irrigation with saline water, in two stages. The first stage was conducted in a greenhouse to evaluate the phenology and production of cowpea genotypes. For this, the experimental design of randomized blocks was adopted, arranged in a 2 x 14 factorial scheme, with five replications. The treatments resulted from the combination of two salinity levels of irrigation water (T1: 0.5 dS m-1 and T2: 4.5 dS m-1 ) and 14 varieties of cowpea purchased from traditional farmers in the West region of the state of Rio Grande do Norte. The second stage was carried out in the laboratory to assess the viability and vigor of the seeds produced in the first stage. The seeds produced in the five replicates of each treatment were homogenized and transformed into batches. In this stage, the experimental design used was completely randomized, arranged in a 2 x 14 factorial scheme, with four replications of 25 seeds, maintaining the treatments of the first stage. The phenological variables and production components were evaluated, as well as the viability and vigor of the seeds through the germination test and seedling dry mass. The bean varieties Branco (V8), Baêta (V11) and Paulistina (V13), presented an early cycle in relation to the others. The condition of high salinity (4.5 dS m-1 ), delayed the days for flowering of the variety Costela de Vaca (V3). The varieties Canário (V5), Baêta (V11) and Coruja (V12) had the highest number of flowers per plant and were the first to start flowering. Salinity reduced the number of flowers per plant and increased the abortion percentage of flowers of all varieties. Saline stress reduced the production of precocious varieties Branco (V8), Canapum-miitão (V10), Baêta (V11) and Coruja (V12). The cultivation irrigated with saline water does not affect the viability of the seeds of the second generation of the varieties Boquinha (V1), Ceará (V2), Ribs of cow (V3), Canary (V5), Roxão (V7), White (V8), Canapum -white (V9), small Canapum (V10), Baêta (V11), Owl (V12), Paulistinha (V13) and Evergreen (V14). Saline irrigation water reduces the vigor of second generation seeds of the varieties Roxão (V7), Branco (V8), Canapum-branco (V9), Canapummiitão (V10), Baêta (V11), Coruja (V12) and Semper -green (V14)