Geocleber Gomes de Sousa

Biomassa, atividade microbiana e FMA em rotação cultural milho/feijão-de-corda utilizando-se águas salinas

Resumo - O objetivo deste trabalho foi avaliar a influencia da irrigacao com agua de alta e baixa salinidade sobre variaveis microbiologicas do solo em area submetida a rotacao de cultura entre milho (Zea Mays L.) e feijao-de-corda (Vigna unguiculata L.). A area destinada ao experimento foi dividida em duas subareas, sendo realizados quatro cultivos: dois cultivos irrigados na estacao seca e dois de sequeiro na estacao chuvosa. O estudo foi conduzido em campo, utilizando-se o delineamento em blocos ao acaso, com cinco repeticoes. Nos cultivos irrigados foram usadas agua com as seguintes condutividades eletricas (CEa): 0,8; 2,2; 3,6 e 5,0 dS m -1 . Os cultivos de sequeiro foram realizados nas mesmas parcelas que foram cultivadas na estacao seca, as quais permaneceram demarcadas e identificadas. No inicio e ao final de ca da cultivo, foram coletadas amostras em duas subareas na regiao radicular das plantas, no terco medio da fileira central de cada parcela. O aumento da salinidade da agua de irrigacao promoveu aumento do numero total de esporos de fungos micorrizicos arbusculares FMA e reduziu a respiracao basal do solo, o carbono da biomassa e o coeficiente metabolico microbiano (qCO 2 ), principalmente na area cultivada com feijao-de-corda. O genero Glomus respondeu por mais de 70% dos esporos totais encontrados, sendo que essa percentagem aumentou nos tratamentos com maior salinidade nos cultivos da estacao seca. Os dados nao evidenciaram qualquer efeito negativo da salinidade residual sobre as variaveis microbiologicas avaliadas, em funcao da irrigacao com agua salina durante os cultivos da estacao seca. Palavras-chave - Estresse salino. Zea mays L. Vigna unguiculata L. Microrganismos.

Irrigação e fertirrigação potássica na cultura da videira em condições semiáridas

The potassium irrigation management and fertigation adjustment may improve grape yield and quality. Aiming at evaluating the biometric and productive characteristics of the ‘Ribier’ grapevine, under five irrigation levels (50%, 75%, 100%, 125% and 150% of the class A pan evaporation - CAE) and five potassium fertilization doses (2, 4, 6, 8 and 10 days), applied by fertigation, two experiments were carried out in a randomized blocks design, with five treatments and five replications, in Limoeiro do Norte, Ceara State, Brazil. The variables bunch number, size and average weight, soluble solids and yield were evaluated for the five irrigation levels, while the bunch average weight and width, number of berries, soluble solids and yield were evaluated for the five potassium fertigation intervals. The maximum irrigation level (150% of the CAE) and the seven days interval for the potassium fertigations provided the best yield for the ‘Ribier’ grapevine, under the Ceara State semiarid conditions.

Crescimento inicial do milho sob diferentes concentrações de biofertilizante bovino irrigado com águas salinas

The purpose of this study was to evaluate the effect of irrigation with water of high and low salinity on the initial growth of corn plants grown in soil fertilized with bovine bio-fertilizer. The experiment was conducted in a greenhouse of the Department of Soil Science - UFC. The seeds were planted in vessels with a 12 kg capacity, containing Alfissol as substrate and one plant per pot. The experiment followed a completely randomized design, in a 5x2 factorial scheme, with four replications, referring to five concentrations of bio-fertilizer: C1 = 50% biofertilizer + 50% water (1:1), C2 = 33.33% biofertilizer + 66.67 + water (1:2), C3 = 25% biofertilizer + 75% water (1:3), C4 = 20% biofertilizer + 80% water (1:4) and C5 = 11.12% biofertilizer + 88, 88% water (1:5) and two salinity levels of irrigation water for S1 = 0.8 dS m-1 (low salinity) and S2 = 3.4 dS m-1 (high salinity). We analyzed the early growth of plants as compared to the readings of electrical conductivity of water saturated soil extracts (ECse) by using the collected data on plant height, stem diameter, leaf area, shoot dry matter, root dry matter and total dry matter. Irrigation with low salinity water was found more efficient in promoting the initial growth of plants under increasing concentrations of biofertilizer, except for root dry matter. Under the same concentrations of biofertilizer, plus irrigation with saline water, soil salinity increased, but did so with less intensity in soil irrigated with low salinity water.

Growth, gas exchange and yield of peanut in frequency of irrigation

This study was conducted to evaluate the effect of different irrigation frequencies on growth, gas exchange and yield of the peanut (Arachis ypogea L). The experiment was conducted in the field using the experimental design of randomized blocks with five treatments, five replications with four plants per plot. The treatments were composed: F2 = (irrigation every 2 days), F4 = (irrigation every 4 days), F6 = (irrigation every 6 days), F8 = (irrigation every 2 days) and F10 = (irrigation every 10 days). At 60 days after sowing (DAS), the gas exchange variables (photosynthesis, stomatal conductance and transpiration) and growth variables (plant height, leaf number, stem diameter and shoot dry matter) were evaluated. The highest irrigation frequency tested (every two days) promoted the best results for plant growth (leaf number, plant height, shoot dry matter) e for leaf gas exchange. The highest yield of field grown peanuts at the conditions prevailing in Fortaleza, Ceara, is associated with the adoption of an irrigation frequency interval of two days.