Photosynthetic pigments and carbohydrates in young Brazil nut (Bertholletia excelsa H.B.K.) plants exposed to moderate and severe water deficiency

Abstract

This study aimed to evaluate the photosynthetic pigments and carbon compounds in young Bertholletia excelsa H.B.K. plants (18-month-old) subjected to 6 and 12 consecutive days without irrigation, to simulate moderate and severe water deficiency. This study will also answer the contribution of the carbohydrates related to osmotic adjustment. The experimental design was a factorial entirely randomised with two water conditions (water deficit and control) and two evaluation times (6 and 12 days), resulting in a total of four measurements. In this study, we measured chlorophyll a, chlorophyll b, total chlorophyll and carotenoids, as well as total soluble carbohydrates, sucrose, starch and reducing carbohydrates. The water restriction induced decreases in all evaluated pigments. The more intense (45%) reduction was found in carotenoids after 12 days of water deficiency. Furthermore, decreases in total soluble carbohydrates and reducing carbohydrates were also observed. In contrast, increases were observed in sucrose and starch levels. The results suggest that water deficiency promotes negative alterations in photosynthetic pigments, while carbon compounds present insufficient responses, aiming to the osmotic adjustment in young B. excelsa plants exposed to water deficit.