Crescimento e índices fisiológicos de melancieira em resposta à fertilização orgânica como alternativa para agricultura familiar

Abstract

Watermelon crop has great social and economic importance in the Brazil and in the world and is an excellent agricultural option for Amapá state, which has climatic conditions favorable to its cultivation throughout most of the year. However, its productivity in the State is limited by fertility problems and soil management. Thus, alternatives are necessary to make the crop viable. It was aimed in this study to evaluate the vegetative growth and physiological indexes of watermelon cultivars as a function of organic fertilization with the use of liquid biofertilizer. The experimente was conducted in a greenhouse at the Federal University of Amapá (UNIFAP), Campus Mazagão, Amapá state, in randomized blocks, with four replications and four useful plants per plot. The treatments consisted of four levels of liquid biofertilizer (50, 100, 150 and 200 mL), and two watermelon cultivars, Crimson Sweet (CS) and Charleston Gray (CG). The plants were grown in pots filled with washed sand, and three seeds were sown per pot of each cultivar. The irrigations were done daily, twice a day, and at 12 days after plant emergence, it was started the application of the biofertilizer, in the afternoon. The respective amounts of biofertilizer was diluted in 50 mL of water and applied according to each treatment. The length of the main branch (CRP, cm), stem diameter (DC, mm), number of leaves (NF, und) and leaf area (FA, cm2 g-1), as well as their respective relative growth rates (TCR), relative water content (TRA, %), stem dry mass (FSC, g), leaves dry mass (FSF, g), roots dry mass (FSR, g) and total dry mass (FST, g) (RPF, g g-1) and root/shoot ratio (RPA, g g-1). Plant growth and plant dry mass production increased linearly as they received larger amounts of biofertilizer. The AFE had an increasing linear response due to the increase of applied biofertilizer levels; while RPF and RPA decreased when there was increase in the biofertilizer. The 'CG' cultivar had the highest leaf growth, in relation to 'CS'. The use of biofertilizer in the nutritional management of watermelon is advantageous and benefits the morphological and physiological aspects of the plant, and it must be tested in other experimental conditions, amounts and proportions of dilution