Temperaturas supraótimas no crescimento e bioquímica da mamoneira

Abstract

The castor bean (Ricinus communis.L) is an important oilseed crop. Its main commercial product is the ricinoleic acid. This crop is easy to grow and it is drought-tolerant. So, it is an interesting option for small farmers in the semiarid region of Brazilian Northeast. Castor crops may be affected by climate change in the future, and the development of this culture would become impossible. The aim of this study was to evaluate and to quantify the effects of temperatures above the optimum temperature for photosynthesis upon growth and biochemical metabolism of different genotypes of castor bean. The experiment was conducted under controlled conditions in phytotron units that simulated different environmental conditions of temperature and moisture. The genotypes BRS Energia, BRS Gabriela, CNPA 2001- 50, CNPA 2009- 7, and BRA 3182 were evaluated in a randomized design with four replicates in a 5 x 2 factorial scheme. The analyzed factors were the 5 genotypes and 2 environmental conditions: 30/20 ºC (day/night) and 40/30 º C (day/night). The castor plants, specially genotypes BRS Energia and BRA 3182, presented significant reduction in the growth rate, plant height, protein content, and some sugars production in the environment 40/30 ºC. The trehalose and sucrose levels were increased, however traces of glucose levels were detected in the HPLC analysis.