Avaliação de Azolla filiculoides no controlo de infestantes e como biofertilizante na produção de arroz irrigado

Abstract

In Mozambique, the use of fertilizers and pesticides is very low and more than 95% of small producers do not use fertilizers, nitrogen is the limiting nutrient in rice production, following the same trend as other cereals. Weeds are one of the biggest constraints for agricultural production made by small producers because activities are normally done manually. However, their yields are around 0.8 to 1.2 ton / ha, considered low in relation to the potential of improved varieties (6 to 7 ton / ha). Azolla is one of the biofertililizers and controls weeds, but so far there is little information in Mozambique about Azolla filiculoides. To assess the effect of Azolla, two trials were conducted at the Umbelúzi Agrarian Station, in Maputo province. The experimental design of each one was made up of complete blocks caused by four repetitions. The weed control trial 5 treatments (control - without Azolla inoculum and no weeding, Monda, with 0.5, 1 and 2 ton / ha of Azolla inoculum and the biofertilizer trial had seven treatments (control - without Azolla + without N, 30 kg / ha of N, 60 kg / ha of N, 90 kg / ha of N, 30 kg / ha of N + 6 ton of Azolla / ha, 60 kg / ha of N + 6 ton of Azolla / ha and 6 ton of Azolla / The results showed significant differences in weed control, obtaining better yields when using treatments containing 1 to 2 ton / ha of Azolla inoculum with 3.35 to 3.45ton / ha, respectively compared to the control treatment (1.87ton / ha) The control treatment had the lowest number of panicles per m 2 (471.25) and 16 plants / m 2 of the abundance of weeds compared to other treatments such as Monda (8 plants / m 2), 0.5ton / ha of Azolla (5 plants / m 2), 1ton / ha of Azolla (4 plants / m 2) and 2ton / ha of Azolla (2 plants / m 2) .In the assay on biofertilizer, the results also showed differences significant differences in yields (where the treatment with Azolla inoculum gave 3.6 ton / ha and which did not differ between 90, 60 and 30 kg / ha of N / ha, with 4.85, 3.69 and 2.79 ton / ha, respectively). A similar trend was also observed when Azolla was combined with 60 and 30 kg / ha of N, with 4.28 and 3.63 ton / ha, respectively. Thus concluding that, this alga can be an alternative for weed control as well as nitrogen fixer for small rice producers. (TRADUÇÃO NOSSA)