Aspectos fisiológicos da emergência e crescimento inicial das mudas de Ormosia arborea (Vell.) Harms em diferentes disponibilidades hídricas

Abstract

In this work aimed to study at evaluating the influence of different water availability in the emergence and initial growth of Ormosia arborea (Vell) harms belonging to the Fabaceae family. Seeds used in all experiments were collected from arrays distributed to the left margin of the Ivinhema river in the municipality of Nova Andradina/MS in April 2015. The seeds used for the production of seedlings were ripped by 10 minutes in concentrated sulfuric acid (98% p.a.) and washed in current water for 5 minutes, subsequently sown in tubes containing red latosol substrate (sifted) and sand in the proportion of 1:1. The first chapter deals with the emergence and metabolic aspects of seedlings under water availability. The experiment was conducted at home of vegetation, under plastic coverage, being the treatments divided into four water availability: 100, 75, 50 and 25% water retention capacity (CRA). For the evaluation of the emergency were determined the percentage, speed index and average emergency time, after 60 days of emergency were evaluated the length of the aerial part, root and total, diameter of the collect, fresh and dry mass of the air and roots, chlorophyll index, fluorescence chlorophyll a, foliar area, photosynthetic and perspiration rate, water usage efficiency Carboxylation efficiency of RUBISCO and intrinsic efficiency of water use, internal concentration of CO2, the water potential and activity of superoxide dismutase and peroxidase enzymes. Based on the results obtained can be reviewed both for emergencies and growths as for the gaseous seedlings of O. arborea the CRA of 75% and 100%. The water availability of 25% and 50% have damaged the emergence and initial growth of the seedlings, as well as the other features studied. In the second chapter, it was studied which water availability appropriate for the production of O. arborea seedlings as well as physiological responses and the activity of antioxidant enzymes to these conditions. The seedlings used possessed six months of age when transplanted and acclimated for 15 days. Irrigation was performed three times a week in the water retention capacities of 25%, 50%, 75%, and 100%. Morphological characteristics and their relations to determining the quality indexes of the seedlings were analyzed at 15, 50, 85 and 120 days after being transplanted. The design was completely randomized design in 4 x 4 factorial scheme (4 water availability X 4 evaluation times), each treatment consisting of 40 seedlings. The height, diameter of the collect, number of leafs, length of root and aerial part, fresh and dry mass of root and air, the water potential, chlorophyll index and fluorescence of chlorophyll a, gaseous exchanges and antioxidant activity of enzymes (superoxide dismutation, catalase and peroxidase). According to the results observed the changes of O. arborea cultivated in the largest water retention capacity (75% and 100% CRA) presented increased growth and chlorophyll index, fluorescence of chlorophyll a and gaseous exchanges, already the 25% CRA influenced negatively and provided the smallest results. Water deficit (25% CRA) has reduced the water potential in the sheets and all the characteristics of the photosynthetic metabolism, with the exception of the instant and intrinsic efficiency of the use (A/E and A/GS) that increased to the smallest available. As stress tolerance the seedlings feature an active antioxidant system proven by the presence of SOD, POD and CAT enzymes.