The aim of this study was to evaluate gas exchange, efficiency of the photosynthetic apparatus, and antioxidant activity in Copaifera langsdorffii Desf. The seedlings were cultivated under different conditions of water availability, in order to improve the utilization efficiency of available water resources. The seedlings were cultivated in four different water retention capacities (WRC-25%, 50%, 75%, and 100%), and evaluated at four different time (T-30, 60, 90, and 120 days). During the experimental period, seedlings presented the highest values for carboxylation efficiency of Rubisco (A/Ci), intrinsic water use efficiency (IWUE = A/gs), chlorophyll index, and stomatal opening, when grown in the substrate with 75% WRC, but the stomatal index (SI) was less the 25% WRC. The efficiency of photosystem II was not significantly altered by the treatments. Comparison between the extreme treatments in terms of water availability, represented by 25% and 100% WRC, represent stress conditions for the species. Water availability causes a high activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) in the plant.

No abstract

No abstract

The Copaifera langsdorffii Desf. seedlings, popularly known as "copaiba" or diesel tree, present a natural occurrence in the riparian forests of the Brazilian Cerrado, however, not much is known about their capacity to recover from flooding, particularly when the focus is on their establishment and use in programs for the recovery of degraded areas near watercourses and subject to flooding. The objective of this study was to evaluate over time the recovery of the efficiency of the photosynthetic apparatus and the antioxidant activity of C. langsdorffii seedlings flooded during different periods. The pots with the seedlings were placed in a plastic tank and submerged with water, and were removed from the flood condition every 21 days (0, 21, 42, 63 and 84 days), and evaluated every 30 days (0, 30, 60, 90 and 120 days). The seedlings tolerated the flooding for up to 42 days, recovering after suspension of this condition. Seedlings flooded for 63 and 84 days showed lower recovery capacity after flooding, independently of the evaluation period. Under these conditions, lower efficiency of the photosynthetic apparatus, gas exchange, photo assimilate production and seedling quality were observed.

ResumoNão existem normas oficiais para o teste de germinação do pinhão manso e são poucos os estudos quanto a tentativa de otimizar a germinação. O objetivo deste trabalho foi avaliar o efeito de diferentes temperaturas e tratamentos pré-germinativos sobre a germinação e vigor de plântulas de pinhão manso. Os tratamentos foram dispostos em delineamento inteiramente casualizado em esquema fatorial com quatro temperaturas (20, 25, 30 e 20-30°C) x dois tipos de sementes (com e sem tegumento das sementes) x seis períodos de pré-embebição (0, 6, 12, 18, 24 e 30h). A semeadura foi realizada em sistema de rolo, com quatro repetições de 50 sementes para cada tratamento. A porcentagem de germinação foi maior na temperatura de 25°C quando o tegumento das sementes foi mantido. Conforme se aumentou o tempo de pré-embebição, maiores foram as reduções da porcentagem de germinação, do índice de velocidade de germinação e da porcentagem de germinação da primeira contagem. A pré-embebição por até 12h propiciou um maior crescimento do hipocótilo. O potencial máximo de germinação e maior vigor de plântulas de pinhão manso foram obtidos a 25°C em sementes que não foram pré-embebidas e quando o tegumento foi mantido. Palavras-chave: Pinhão manso; Pré-embebição; Tegumento; Temperatura AbstractEffect of temperature and pre-germination treatments on seed germination and seedling vigor of Jatropha curcas L. To date, there are no official methods used to test the seed germination of physic nut (Jatropha curcas) and there have only been a few attempts to optimize the germination of this species. The objective of this study was to evaluate the effect of different temperatures and pre-germination treatments on the germination and seedling vigor of J. curcas. The treatments were arranged in a completely randomized factorial scheme with four temperatures (20, 25, 30 and 20-30°C) x two types of seeds (with and without the seed tegument) x