Deficiências de macronutrientes em mudas de maracujazeiro-amarelo cultivadas em soluçao nutritiva

Abstract

Com o objetivo de caracterizar os sintomas visuals de carencia mineral de macronutrientes em mudas de maracuja-amarelo (Passflora ed'ul is Sims f. ftavicarpa Deg,) cultivadas em suluÇao nutritiva, foi conduzido um experimento composto de site tratamentos: completo, completo corn omissSo de N, completo corn omissla de P, completo cam ornissav de K, completo corn omissdo de Ca; completo corn omissdo de Mg e completo corn ornissao de S, corn quatro repetiOes em blocos casualizados. Durante 36 dial foram feitas observaq6es de sintomas visuals e mensura0o de altura de planta, area foliar e nurnero de foihas. Ms 36 dias apps o inicio dos tratamÇnntos as plantar foram cvlhidas, separadas em Fame aerea e sistema radicular, secas, moidas e analisadas quanta aos teores de N, P, K, Ca, Mg e S. A deficiência de N caracteriznu-se por amarelecimento generalizado das folhas, iniciando-se os sintomas petal mail velhas, reduÇao drdstica no crescimento, senescencia precoce e ausencia de gavinhas e de folhas palma4ripartidas. A eficiência de calcio provocou escurecimento de rages, encarquilhamento de folhas, reduçao no crescimento do sistema radicular e da parte area, pontos necróticos na metade inferior das folhas novas que ao coalescer formaram areas esbranquiçadas e depots necróticas entre as nervuras. A carencia cue magnésio resultou em clorose malhada internerval das folhas mats velhas, permanecendo as nervuras verdes por mats tempo. Plantas deficientes em enxofre mostraram clorose generalizada das folhas, mats intensa na porno superior da planta e nos bordos foliares. As deficiências de P e de K resultaram em sintomas pouco caracteristicos. A omisslo de nutrientes limitou o crescimento em altura, o numero de folhas emitidas, a area foliar e o acumulo de mat6ria secs na seguinte ordem decrescente de intensidade: N > Mg > S > Ca > F > K. as teores adequados de macranutrientes na parte aerea das plantar com 76 dial de idade foram 2,6; U,38; 3,7; 1,5; 0,18; e 0,21 dag/kg de N, P, K, Ca, Mg e S, respectivamente. Plantar deficientes presentaram 0,8; 0,20; 0,05; e 0,09 dag/kg de N, Ca, Mg e S, respectivamente. As sizes de plantas bem nutridas apresentaram 2,80; 1,29; 5,10; x,50; Q,25; e 0,15 dag/kg de N, P, K, Ca, Mg e S, respectivamente, enquanto que em plantas deficientes esses valores reduziram-se pars 0,8; 0,06; 0,04; e 0,0.7 dag/kg de N, Ca, Mg e S, respectivamente

The objective of this work was to characterize the visual symptoms of mineral deficiencies of macronutrients in yellow passionfi'uit plantlets (Passiflora edulis Sims f. flavicarpa Deg.) cultivated in nutritive solutions. Seven treataments were applied: complete, without N, without P, without K, without Ca, without Mg and without S, with four replications in a randomized 'complete-block During 36 days, observations of the visual symptoms were made and plant size,leaf area and nurnber were measured. Plants were harvestd 36 days after the begining of the treatments, separating the aerial part and root system, and then dried, milled and analyzed for N, P, K, Ca, Mg and S contents. The N deficiency was characterized by a generalized chlorosis of the leaves (the symptoms starting in the old leaves), drastic growing reduction, early senescence and absence of adult leaves (palm-tripartite type). The mineral deficiency of calcium promoted darkish roots. growing reduction of the root system and of the aerial part, necrotic points in the lower part of the young leaves showing white and. later necrotic areas among the veins. The magnesium deficiency resulted in chlorosis among the veins (called internerval chlorosis) in the old leaves, and the veins remained green during a long time. Sulphur deficient plants showed general chlorosis in their. leaves, which became intense on the top of the plants (young leaves). P. and K mineral deficiencies did not Show characteristic symptoms. The omission of nutrients limited plant growing, leaf number, leaf area and dry matter in the following order: N > Mg > S > Ca > P > K. A satisfactory macronutrient content in the aerial part of the plants at 76 days of age was 2.6, 0.38, 3.7, 1.5, 0.18 and 0.21 dag/kg of N, P, K, Ca, Mg and S, respectively. Deficient plants showed 0.8, 0.20, 0.05 and 0.09 dag/kg of N, Ca, Mg and S, respectively. Plant roots With. adequated mineral nutrition showed 2.80, 1:29, 5.10, 0.50, 0.25 and 0.15 dag/kg of N, P, K, Ca, Mg and S respectively. In deficient plants these dates decreased to 0.8, 0.06, 0.04, and 0.07 dag/kg qu, Ca, Mg and S, respectively.