Doses de nitrogênio e inoculação com Azospirillum sp. em alface americana cv. Lucy Brown

Abstract

Lettuce (Lactuca sativa L.) is presented as one of the most consumed holerícolas in Brazil and in the world, and for its cultivation nitrogen (N) is the required element and the more limited its growth. This study aims to evaluate the influence of nitrogen and nitrogen fertilizati on in association with nitrogen fixing bacteria of the genus Azospirillum sp. on the development of lettuce cultivar Lucy Brown. The experiment was conducted in the experimental area of the campus UFMT during the period from August to October 2015. The experimental design to be used was the completely randomized blocks (DIC) in 2x4 factorial design (with inoculation and without inoculation with Azospirillum and 4 N rates (50, 100, 150, and 200 kg ha) with 4 repetitions totaling 32 installments. We evaluated internal head diameter, outer diameter of the head, stem diameter, fresh weight of shoot, dry weight of shoot , number of leaves, leaf area, leaf area index, nitrate content. the data were submitted to variance analysis by test-F and when significant for quantitative parameters subjected to regression analysis. the results show that inoculation with Azospirillum in American lettuce cv. Lucy Brown did not affect qualitative parameters, becoming apparent only the presence of significant responses only to the effect of dose. the best results for the fresh weight variables (245.15 g plant-¹), dry weight (13 , 73 g plant-1), leaf area (2833.1 cm 2 plant-1), and nitrate content (0,665 g NO3-for g dry mass ) were obtained with a dose of 150 kg ha-1 N, with the exception of index leaf area whose highest value (1.36 cm2 plant-1) was obtained with the dose of 50 kg ha-1 N, as for other parameters (inner diameter of the head, external diameter of the head, stem diameter and number of leaves). They were observed infirm significant response to the same in relation to doses of N.