Janivan Fernandes Suassuna

TROCAS GASOSAS E EFICIÊNCIA FOTOSSINTÉTICA EM ECÓTIPOS DE FEIJOEIRO CULTIVADOS NO SEMIÁRIDO

Common bean has a significant economic and social importance, although its yield is considered low in Brazil, due to environmental conditions and low technology level on farming. So, the use of promising cultivars may be a strategy to improve its cultivation in the Brazilian semiarid region. This study aimed to evaluate gas exchange, instantaneous water use efficiency, leaf area, biomass, leaf water content, and photosynthetic efficiency in three common bean ecotypes ( Eco 1 = G2227 , Eco 2 = BRA 130583 and G6490, and Eco 3 CIAT BAT = 477) cultivated in the semiarid region of the Paraiba State, Brazil. A randomized blocks design with three replications was used. The CO 2 assimilation rate , transpiration, intercellular CO 2 concentration , instantaneous carboxylation efficiency , instantaneous water use efficiency (from 9 a.m. to 10 a.m. and from 10 a.m. to 11 a.m.) , leaf area, leaf area index , leaf water content, and photosynthetic efficiency were analyzed . The common bean ecotypes showed variations in the gas exchange rate and instantaneous water use efficiency along the day, under the environmental semiarid conditions of the Paraiba State. The leaf area and photosynthetic efficiency did not differ significantly in the conditions studied. The G2227 ecotype showed the best physiological responses, concerning CO 2 assimilation and carboxilation efficiency, besides presenting a smaller variation for instantaneous water use efficiency, from 9 a.m. to 11 a.m., pointing out a better adaptation level to semiarid conditions and cultivating potential.

Photochemical efficiency and yield of melon plants cultivated under different irrigation levels

The melon crop has great social and economic importance to Northeastern Brazil, however, lack and excess of water affect growth. Therefore it is necessary to determine ideal water amount to obtain the maximum yield. This research work aimed to evaluate photochemical efficiency and yield of Cantaloupe melon under different irrigations levels. The work was carried in field conditions, adopting a randomized block design with 4 treatments [(60, 80, 100, and 120% of ET0 (mm day-1) corresponded to the volume of water accumulated during the cycle: 1250, 1680, 2110 and 2540 m3 cycle-1, respectively, and 6 replications with 10 plants per experimental unit. The following variables were analyzed: chlorophyll fluorescence, yield and physical and chemical attributes fruits. The 80% ETo water level provided the higher efficiency DOI: 10.5433/1679-0359.2011v32n4p1251

Chlorophyll and macronutrients content in leaf tissue of Musa sp ‘Prata-Anã’ under fertigation

1 Paraiba State University, Av. das Baraunas, 351, Bodocongo, CEP 58109-753, Campina Grande-PB, Brazil. 2 Department of Agricultural Engineering, Sergipe Federal University, Av. Marechal Cândido Rondon, Jardim Rosa Elze, CEP 49100-000, Sao Cristovao-SE, Brazil. 3 Campina Grande Federal University, Academic Unit of Agricultural Sciences, Av. Jairo Vieira de Feitosa, Pereiros, CEP 58840-000, Pombal-PB, Brazil. 4 EMBRAPA, Agricultural Research Center of Tabuleiros Costeiros, Av. Beira Mar, 3250, Jardins, CEP 49025-040, Aracaju-SE, Brazil. 5 Department of Agronomy, Paulistan State University Julio de Mesquita, CEP 14884-900, Jaboticabal, SP, Brazil.