Effect of the phytosanitary treatment of seeds on the initial growth of upland rice

Resumo

The initial growth of plants is a crucial period in the development cycle of the different crops of agricultural interest. This phase is the target of attack by different pests that drastically reduce this growth. Commonly, chemical pesticides are used in order to control the attack, but little has been elucidated about the effect of their contact with the seed. Therefore, the work aimed to evaluate the effect of the phytosanitary treatment of seeds on the initial growth of upland Oryza sativa L. For such, four seed treatments were tested (T1 - no seed treat­ment, T2 - fipronil + pyraclostrobin + thiophanate-methyl, T3 - thiamethoxam + carbendazim, thiram and         T4 - imidacloprid + thiodicarb) in six evaluation periods (28, 35, 42, 49, 56 and 63 days after emergence). The de­sign was a randomized block. The variables determined were dry mass of root, dry mass of shoot, root length, plant height, leaf area and chlorophyll content. The use of chemical treatments in upland rice seeds yielded positive effects against all morphological variables studied, except chlorophyll content. The treatment consisting of fipronil + pyraclostrobin + thiophanate-methyl provided greater increase of the morphological variables. The chemical treatments in seeds corresponded to a differentiation in the post-emergence vegetative development of seedlings for the characteristics of dry mass of root, dry mass of shoot, root length, plant height and leaf area, promoting greater initial growth of the crop in this period.