Crescimento E Trocas Gasosas Do Feijão Caupi Cv. BRS Pujante Sob Níveis De Água Disponível No Solo E Cobertura Morta

Abstract

CRESCIMENTO E TROCAS GASOSAS DO FEIJÃO CAUPI CV. BRS PUJANTE SOB NÍVEIS DE ÁGUA DISPONÍVEL NO SOLO E COBERTURA MORTA TARSO MORENO ALVES DE SOUZA1; TÁSSIO ALMEIDA SOUZA1; LAUTER SILVA SOLTO2; FRANCISCO VANIES DA SILVA SÁ3; EMANOELA PEREIRA DE PAIVA4; MARCOS ERIC BARBOSA BRITO2 E EVANDRO FRANKLIN DE MESQUITA5 1Graduando em agrônomia, Unidade Acadêmica de Ciências Agrárias, Universidade Federal deCampina Grande, Pombal, PB. E-mail: tarsomoreno.agro@gmail.com; tassiobuzu@hotmail.com.2Eng. Agrônomo, Doutor, Professor da Unidade Acadêmica de Ciências Agrárias, Universidade Federal deCampina Grande, Pombal, PB. E-mail: lauter@ccta.ufcg.edu.br; marcoseric@ccta.ufcg.edu.br .3Engenheiro Agrônomo, Doutorando em Engenharia Agrícola, Universidade Federal de Campina Grande – UFCG, Centro Tecnologia e Recursos Naturais – CTRN, Campina Grande - PB, Brasil. E-mail: vanies_agronomia@hotmail.com.4 Eng. Agrônoma, Doutoranda em Fitotecnia, Departamento de Ciências Vegetais, Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró, RN. E-mail: emanuelappaiva@hotmail.com.5Engenheiro Agrônomo, Doutor, Professor Adjunto, Centro de Ciências Humanas e Agrarias (CCHA), Universidade Estadual da Paraíba (UEPB), Catolé do Rocha, PB, e-mail: elmesquita4@uepb.edu.br. 1 RESUMO O feijão-caupi é amplamente cultivado em regiões áridas e semiáridas, onde o déficit hídrico é um fator limitante à produção das culturas, sendo necessária adoção de práticas que melhorem o desempenho da cultura. Com isso, objetivou-se avaliar o efeito de níveis de água disponível no solo com e sem cobertura morta sobre a superfície do solo, sob o crescimento e atividade fotossintética do feijão Caupi (Vigna unguiculata Walp.), cv. BRS Pujante. O trabalho foi desenvolvido no Centro de Ciências e Tecnologia Agroalimentar da Universidade Federal de Campina Grande, usando-se um delineamento experimental inteiramente casualizado, com tratamentos arranjados em esquema fatorial, 5 x 2, correspondentes aos níveis de água disponível (AD) de 20; 40; 60; 80 e 100%, mantido após as irrigações do solo, em função da cobertura morta (CC) e sem cobertura (SC), e quatro repetições, totalizando as 40 unidades experimentais. Aos 45 dias as plantas de feijão caupi foram avaliadas quanto ao crescimento e trocas gasosas. O maior crescimento em número de folhas e área foliar da cultivar BRS Pujante ocorre em cultivos com água disponível no solo acima de 75%. A cobertura do solo reduziu os efeitos do estresse hídrico sob o crescimento das plantas. O mecanismo de tolerância das plantas da cultivar BRS Pujante está relacionado à redução do número de folhas e da área foliar e o aumento das trocas gasosas nas folhas restantes. As plantas de feijão Caupi cultivar BRS Pujante apresentam altos índices de eficiência do uso da água sob condições de baixa disponibilidade hídrica. Palavras-chave: semiárido, deficit hídrico, fisiologia. SOUZA, T. M. A. de; SOUZA, T. A.; LAUTER SILVA SOLTO; SÁ, F. V. da S.; PAIVA, E. P. de; BRITO, M. E. B.2 E MESQUITA, E. F. deGROWTH AND GAS EXCHANGE OF COWPEA CV. BRS PUJANTE BEAN UNDER LEVELS OF AVAILABLE WATER IN THE SOIL AND MULCH2 ABSTRACT Cowpea is widely cultivated in arid and semiarid regions, where drought is a limiting factor to crop production, requiring the adoption of practices to improve the culture performance. In this context, the study was intended to assess the effect of levels of available water in the soil with and without mulch on the soil surface, in the growth and photosynthetic activity of Cowpea (Vigna unguiculata Walp.), cv. BRS Pujante bean. The study was conducted at the Centre for Science and Agrifood Technology of Federal University of Campina Grande, using a completely randomized design, with treatments arranged in a factorial scheme 5 x 2, corresponding to the levels of available water (AD) 20; 40; 60; 80 and 100%, maintained after soil irrigations, as function of mulch (CC) and without cover (SC) and four repetitions, totaling the 40 experimental units. After 45 days the cowpea plants were evaluated for growth and gas exchange. The highest growth in number of leaves and leaf area of BRS Pujante occurs in crops with water available in the soil above 75%. The soil cover reduced the effects of water stress on plant growth. The mechanism of tolerance of BRS Pujante plants is associated to the reduction of the number of leaves and leaf area and the increase of gas exchange in the remaining leaves. The cowpea cultivar BRS Pujante presents high levels of water use efficiency under conditions of low water availability. Keywords: semiarid, water deficit, physiology.

Gas exchanges and water-use efficiency of Nopalea cochenillifera intercropped under edaphic practices

“…In the soil covered with vegetal remains, the FC × B; FC × M, and FC × S intercropping systems provided higher values for this variable, whereas in the uncovered soil the highest results were obtained with the FC × B, FC × M, and FC × FW intercropping systems (Figure 3). For Santos et al (2016), the use of mulch provided good The higher stomatal conductance (g s ) of the plants cultivated in the mulched soil ( Figure 1A) contributed directly to these results since the increment in the C i values is accompanied by increases in the g s ; therefore, the stomatal limitation would be the main factor for the restriction of the photosynthetic performance, considering that the greater is the stomatal opening, the greater will be the CO 2 partial pressure in the intercellular spaces, favoring the diffusion of CO 2 for the substomatal cavity, and thus increasing the substrate for the activity of Ribulose 1,5 biphosphate carboxylase/oxygenase (Rubisco) (Silva et al, 2015;Souza et al, 2016). The instantaneous water-use efficiency ( Figure 4B) by the forage cactus was favored (p < 0.05) when of the intercropping with buffelgrass and forage watermelon (1.33 and 1.10 µmol m -2 s -1 /mmol of H 2 O m -2 s -1 , respectively).…”

“…especially those cultivated in the soil under mulch cover, presented photosynthesis rates above this average rate.This may be an indicator of the highest growth rate of the forage cactus, which allows annual harvests for the crop in comparison to native cacti, which possess a slower annual growth rate.The relative advantages of the use of soil mulch on the photosynthesis rates of the plants possibly occurred due to the reduction of the negative effects of solar radiation, such as the wind speed on the edaphic surface, essential in semiarid soils, in which the reference evaporation can reach 12 mm/day -1 even in the rainy season, more precisely in the first semester. The highest stomatal conductance observed in the plants cultivated under this edaphic management (Figure 1A) stimulated the photosynthesis rate as a function of the greater stomatal opening and the greater availability of substrate for the activity of RUBISCO during the day(Souza et al, 2016). The use of soil mulch is a recommended practice, particularly for these regions, since besides maintaining the soil more humid and less heated, it reduces soil water losses and also superficial erosion, contributing to the improvement of crop performance(Lima et al, 2015) Borges et al (2014).…”

Photosynthetic efficiency and production of cowpea cultivars under deficit irrigation

“…It should be pointed out that Ci accumulation in the leaf mesophyll is directly associated with stomatal closure and reduction in CO2 assimilation (Paiva et al, 2005). Souza et al (2016) also observe this fact, in cowpea cv. BRS Punjante, where the increase of Ci concentration in the lower levels of water availability corroborated with the lower levels of photosynthesis.…”

Influência da cobertura morta vegetal e da salinidade sobre as trocas gasosas de genótipos de amendoim

“…A baixa eficiência no uso da água para o genótipo BR-1 quando comparado ao acesso 43, pode estar relacionado a variabilidade existente entre os acessos da espécie (BORGES et al, 2007). Este resultado corrobora com os encontrados por Souza et al (2016) trabalhando com a cultura do feijãocaupi, em que houve eficiência do uso da água pelo cultivar BRS Pujante.…”