INFLUÊNCIA DO THIDIAZURON E DA INOCULAÇÃO COM Azospirillum brasilense NO CRESCIMENTO E PRODUTIVIDADE DO ARROZ DE TERRAS ALTAS

Abstract

A inoculação com bactérias do gênero Azospirillum pode contribuir com o fornecimento de nitrogênio (N) e com o crescimento das plantas, pois esses microrganismos são também promotores de crescimento. Por outro lado a aplicação nas doses e épocas adequadas do regulador vegetal de efeito citocinínico thidiazuron (TDZ) pode vir a beneficiar a produtividade de grãos. Dessa maneira, o objetivo do trabalho foi avaliar o efeito de doses de TDZ sobre a produtividade do arroz, na presença e ausência da inoculação foliar com Azospirillum brasilense. Foi utilizada a cultivar ANa 5015, no delineamento experimental de blocos casualizados em esquema fatorial 4 x 2, sendo quatro doses de TDZ (0,0; 0,5; 1,0 e 1,5g ha -1 ) aplicadas por ocasião do perfilhamento, 30 DAE, e da aplicação de Azospirillum brasilense (presença ou ausência) em dose fixa aos 20 DAE. Verificou-se que a cultivar ANa 5015 não se mostrou responsiva para a inoculação foliar com Azospirillum brasilense na dose de 200 mL ha -1 . Para as doses de TDZ aplicadas via foliar, houve uma variação significativa na altura de plantas, cuja dose de 0,41 g ha -1 resultou na altura máxima de 1,11 m. Não houve efeito das doses de TDZ na produtividade, massa de 100 grãos, número de panículas por m², grãos por panícula e massa hectolítrica. Palavras-chave: bactérias diazotróficas, irrigação por aspersão, Oryza sativa L., thidiazuron INFLUENCE OF THIDIAZURON AND INOCULATION WITH Azospirillum brasilense IN THE GROWTH AND PRODUCTIVITY OF HIGHLAND RICE ABSTRACTInoculation with bacteria of Azospirillum genus may contribute with the nitrogen (N) supply and the plant growth, since these microorganisms are also growth promoters. On the other hand the application in the appropriate doses and times of the plant regulator of cytokinin effect thidiazuron (TDZ) may benefit grain yield. Thus, the goal of this work was to evaluate the TDZ dose effect on rice yield, in the presence and absence of leaf inoculation with Azospirillum brasilense. The cultivar ANa 5015 was used in the experimental design of randomized blocks in a 4 x 2 factorial scheme, four TDZ (0,0; 0,5; 1,0 and 1,5g ha -1 ) doses applied on the occasion of tillering , 30 DAE, and the application of Azospirillum brasilense (presence or absence) at a fixed dose at 20 DAE. It was verified that the cultivar ANa 5015 was not responsive to the leaf inoculation with Azospirillum brasilense at the dose of 200 mL ha -1 . For TDZ doses applied via leaf, there was a significant variation in plant height, whose *

Interaction between thidiazuron and Azospirillum brasilense on yield characteristics and productivity of rice

“…The hectoliter mass, the mass of 100 grains and the yield of rice grains were unaffected by inoculation with A. brasilense in the two harvests studied ( Table 2). The same was observed by Gitti et al (2012) and Garé et al (2017), corroborating the results of the present study. Considering this, the idea that the mode of inoculation used (foliar route) is not very effective could be conceived and, therefore, was the reason for not obtaining significant results in the analyzed variables.…”

“…Like the results of this study, the number of panicles per m 2 for the two cultivars used was not affected by TDZ in the studies of Alves et al (2015) and Garé et al (2017). However, cytokinins may stimulate the development of tiller buds in rice plants by promoting the proliferation of lateral meristems and breaking dormancy, facilitating lateral sprouting in certain crops (Yookongkaew et al, 2007;Liu et al, 2011).…”

“…BRS Esmeralda due to the foliar application of A. brasilense and doses of thidiazuron (2015/16 and 2016/17) application or even the environmental conditions in which the cultivation was carried out. In the works of Gitti et al (2012), Garcia (2017) and Garé et al (2017), there was no effect of inoculating seeds with this bacterium, as in the present work. Rodrigues et al (2015) observed that there was interaction between the factors cultivar and inoculation, so that only cv.…”

“…As for the application of thidiazuron, Garé et al (2017) also did not notice response to the doses of this regulator for the total amount of spikelets nor for the quantity of filled and unfilled grains per panicle. On the other hand, Alves et al (2015) demonstrated that the dose of 0.9 g ha -1 of TDZ resulted in a 13.4% increase in the amount of spikelets per panicle in relation to the control treatment.…”

“…In the work of Alves et al (2015), for example, TDZ doses had no effect on the plant height of the two cultivars used (BRS Esmeralda and IAC 202). On the other hand, Garé et al (2017) demonstrated that the height of cv. ANa 5015 was adjusted to a quadratic equation as a function of TDZ doses, whose estimated maximum value was 1.11 m with a dose of 0.41 g ha -1 .…”