Ciro de Miranda Pinto

Trocas gasosas em folhas de sol e sombreadas de cajueiro anão em diferentes regimes hídricos

Resumo - Foram analisadas as variacoes sazonais nas taxas de trocas gasosas em lâminas foliares, sombreadas e a pleno sol, de cajueiro anao precoce (Anacardium occidentale L.), quando submetidas aos regimes de irrigacao e de sequeiro. Os clones CCP 76 e BRS 189 foram mensalmente avaliados quanto ao seu desempenho fisiologico em relacao a condutância estomatica (g s ), as taxas transpiratorias (E) e fotossinteticas (A), a temperatura foliar e a relacao entre as concentracoes interna e externa de CO 2 (C i /C e ). O experimento foi conduzido entre setembro de 2006 e agosto de 2007, na estacao experimental da Embrapa Agroindustria Tropical, localizada no municipio de Paraipaba, Ceara. As variaveis A, g s , E e C i /C e fo ram afetadas apenas em funcao da epoca do ano e dos tipos de folhas. A maior influencia nos fatores fisiologicos analisados ocorreu devido as condicoes em que as folhas estavam submetidas (sol ou sombra) e aos fatores meteorologicos e nao a supressao da irrigacao. Isto, possivelmente porque os resultados aqui obtidos estejam mais bem relacionados com as fases fenologicas da cultura do que com os tratamentos, demonstrando assim o conspicuo efeito fisiologico da forca dos drenos e da irradiância nessas plantas. Palavras-chave - Anacardium occidentale. Estresse hidrico. Ecofisiologia vegetal.

INFLUÊNCIA DA COBERTURA MORTA NA PRODUTIVIDADE DE MILHO E FEIJÃO-CAUPI EM SISTEMA PLANTIO DIRETO

The success of no tillage system is directly related with the remaining of crop residues on soil surface, the quality and quantity of straw and its mineralization promoting recycling of the nutrients. The aim of this study was to evaluate the contribution of straw from spontaneous vegetation, millet (Pennisetum americanum sin. tiphoydes), brachiaria (Brachiaria brizantha); sorghum forage (Sorghum bicolor L Moench), and the straw from conventional tillage, on corn and cowpea grain yield under two minimum tillage systems: SPD1 (corn following cowpea) and SPD2 (cowpea following corn), under the semiarid conditions of the Quixada County, Ceara, Brazil, during 2008 and 2009. It was evaluated also the period of duration of the straw on soil surface and the rate of decomposition of the straw from corn and cowpea. The straw yield from spontaneous vegetation was around 6.0 t ha-1 similar to the yield of the others soil biomass covers in both SPD1 and SPD2 minimum tillage systems. The degradation of the vegetal residues to the soil at the end of two years of evaluation was greater when the dry matter from cowpea was used as straw when compared with the straw from corn. The grain yield of corn from the different death cover was significantly lower than the conventional in 2008 and 2009. The cowpea yield was higher from conventional planting than from than the minimum tillage with different straw covers.

MAMONA E GIRASSOL NO SISTEMA DE CONSORCIAÇÃO EM ARRANJO DE FILEIRAS: EFICIÊNCIA BIOLÓGICA

An experiment field was carried in the agricultural seasons 2008, 2009 and 2010, with aim of studying the response of castorbean (Ricinus communis L.) intercropping with sunflower (Helianthus annus L.) in row arrangement in the dryland farming conditions. In addition, it was evaluated the biological efficiency of plants in intercropping systems.The design used in the experiment was randomized block with seven treatement and four replications. The treatments were represented by rows of castor oil (Ma) and sunflower (Gi) listed below: 1Ma:1Gi; 1Ma:2Gi; 1Ma:3Gi; 2Ma:2Gi; 2Ma:3Gi; castor and sunflower in the monoculture. The efficiency of intercropping was measured by LER, ATER, LEC, average between LER and ATER, SPI and CoR. The grain yield of castor bean and sunflower were reduced in intercropped row arrangements. The row arrangement 1Ma:2Gi showed the smallest reduction of average productivity of castor beans and sunflower in the evaluation period of the experiment. The castor bean was the dominant crop in relation to sunflower.