ABSTRACT
In order to select species for using in the restoration of riparian forests on the banks of the Sao Francisco River, in the state of Sergipe, an experiment was conducted to evaluate the growth and gas exchange of plants Lonchocarpus sericeus (Poir.) D.C., subject to flooding conditions in the nursery. The experiment was conducted at Forest Nursery, Department of Forest Sciences, Federal University of Sergipe (UFS), the municipality of São Cristóvão, (11 º 01 'S latitude and 37 º 12' longitude W, altitude 20 m) , state of Sergipe, Brazil, from October 2006 to January 2007 under ambient conditions. We used a completely randomized design (CRD), factorial (2x7), two treatments (control - T0, plants at field capacity and flooded - T1) and days after flooding (0, 15, 30, 45, 60, 75 and 90 days). To simulate the condition of flooding, the plants were placed in plastic pots of black color with a volume of 5 L and more substrate. Following these pots were attached to pots with a volume of 10 L, which was added water until it reaches a water depth of 5 cm above the top of the plants. The control plants kept in pots with a volume of 5 L substrate maintained at field capacity. In non-destructive variables were used four replicates per treatment evaluated every fifteen days, where each replicate consists of six plants, totaling 24. Destructive variables used were 4 replicates per treatment, determined biweekly from 15 days after flooding, where each replicate consists of a plant totaling 24 plants. Therefore, 48 plants were used per treatment. The non-destructive variables were height, diameter and number of leaves. While the destructive variables analyzed were dry weight of roots, dry weight of shoots and dry weight of root / shoot ratio. In addition, we carried out analysis of gas exchange on a monthly basis and evaluated twelve plants per treatment, with two sampling leaves, fully expanded, per plant. The biometric variables were subjected to analysis of variance and subsequently the average test (Tukey p <0.05), while the values of gas exchange were taken from the standard deviations of the mean. Thus, we observe that the flooding caused a reduction in height and dry mass of root / shoot ratio, from 30 days after treatment application. In addition, flooded plants showed morphological changes such as hypertrophy of adventitious roots and lenticels, characteristics of species tolerant to flooding. The net photosynthetic rate has been reduced by 48.20% compared to control after 60 days. However, despite reductions in growth variables and gas exchange species Lonchocarpus sericeus showed promise in the recovery of riparian vegetation, due to its morphological characteristics of species tolerant to flooding.
Keywords:
adventitious roots; hypertrophied lenticels; net photosynthetic rate