A study of various methods of irrigation on nine cultivars of rice (Oryza sativa) in the Fluminense basin

Abstract

The present investigation was conducted on a hydromorphic soil of the "Guandu" series at the Fluminense basin in the State of Rio de Janeiro. The principle objective of the study was related to the controverted modes of irrigation by continuous or permanent and periodical or intermittent flooding of rice (Oryza sativa L.). The experiment was made with following nine cultivars of the cereal: "Amarelão", "De Abril", "Honduras", "Iguape Agulha", “H-12-V-13", "7-V-8", "IAC-435", "Reg. IPEACS 132" e "Mas-M-24". After nine years of experimentation the following conclusions were reached. a) the differences of production obtained between the various modes of irrigation were not statistically significant; b) there was no influence of these modes on the bedding nor in the sanitary status of the cultivated cultivars which were used in the experiment; however, it was noted that the intermittent system of managing the water, the drainages made we sufficient enough to control the mollusk (shellfish) Ampullaria sp.; c) of the nine cultivars used in the investigations, two had special performance in relation to productivity; "De Abril" and "Mas-M-24" with average production from 5.027 and 5.569 per kg/ha, respectively. The others species produced lower yields; d) as it was expected the mode of irrigation by periodical flooding decreased the percentage of nitrogen and the quantities of calcium + magnesium in the soil, however, it appears that this process had no influence on the pH nor on the amounts of carbon, aluminium, phosphorus and potassium; e) the rapid and gradual method of removing the water from the seed beds does not seem to influence the results obtained; f) in the nine years of experimentation, the pluviometric rates recorded during the drainage period, were not considered as satisfactory and must have favored the intermittent irrigation mode.