Dotações hídricas e populações de plantas na cultura da mamoneira cv. BRS Energia.

Abstract

The cultivation of castor plants in the Northeast of Brazil stands as alternative for creatin of employment and income in the family agriculture. The objective of the present study was to verify the effects of different water depths and populations of castor plants (Ricinus communis L.) cv. BRS ENERGIA, from germination to production. Two experiments were carried out in Experimental Farm Embrapa Algodao, located in the district o f Barbalha-CE, in randomized block design with plots in strips. In Experiment I sixteen treatments resulting from the factorial combination of four water depths (294.22; 382.50; 479.75 and 679.75 mm) and four populations of plants 35,460 plants ha"1 (0.60 m x 0.47 m), 39,682 plants ha"1 (0.60 m x 0.42 m), 45,045 plants ha"1 (0.60 m x 0.37 m) and 52,083 plants ha"1 (0.60 m x 0.32 m) in four repetitions. Were used the Experiment I I conducted is same design as of Experiment I and the same number of treatments and the factorial combination of four irrigation depths (311.74; 460.40; 668.53 and 850.54 mm), and four population of plants 27,777 plants ha"1 (0.60 m x 0.60 m), 33,333 plants ha"1 (0.60 m x 0.50 m), 41,666 plants ha"1 (0.60 m x 0.40 m) and 55,555 plants ha"1 (0.60 m x 0.30 m) with four repetitions. The irrigation method used was by aspersion, where the water depths were in accordance with line source sprinkler irrigation in relation to the irrigated strips. Oh the base of results of the study, it was verified that irrigating with a water depths of 668,53 mm the maximum response to plant height (111,43 cm); leaf area (8.111,78 cm2); rate of absolute growth of plant height (1,94 cm day"1); leaf area index (3,25 m2 m"2) and productivity (2.678,38 kg plant"1) was obtained. The values for these variables were on average 8% superior in comparison to those obtained with of the irrigation water depths 460.40 mm, which is recommended, considering the edaphclimatics characteristics of Microregion of Cariri in the State of Ceara/Brazil, due the economy of the 208,00 mm of the water depths in the crop cycle. In relation to the population o f plants the best results for the growth variables and development were obtained with the population of 27,777 plants ha"1 (0.60m x 0.60m), with 2,282.74 kg ha"1 productivity.