Moisture stress on physiology and yield of some indigenous leafy vegetables under field conditions

Abstract

South Africa is rich with a diverse range of leafy vegetables that are rich in nutrients. African leafy vegetables (ALVs) are limited in terms of their commercial production due to lack of production information such as water requirements and yield. The effect of water stress on growth, physiology and yield of ALVs were evaluated under field conditions at the Agricultural Research Council (ARC), Roodeplaat, Pretoria, over two seasons, 2015/2016 and 2016/2017. A randomised complete block design was used with: three water levels [30%, 60% and 100% of crop water requirement (ETc)] and four ALVs (Amaranthus cruentus L., Corchorus olitorius L, and Vigna unguiculata (L.) Walp and Beta vulgaris L.), replicated three times. In A. cruentus, moisture stress (30% ETc) reduced plant height, chlorophyll content index (CCI) as well as yield. In B. vulgaris leaf number, plant height and yield were reduced by water stress. In both A. cruentus and B. vulgaris, yield increased with increase in water application from 30% ETc to 60% ETc and remained the same at 100% ETc. For C. olitorius and V. unguiculata, CCI, plant height and yield were not affected by water stress although stem fresh mass was reduced by water stress in V. unguiculata. Using 60% ETc appears ideal for production of A. cruentus and Beta vulgaris, whereas 30% ETc is recommended for V. unguiculata and C. olitorius. Results of A. cruentus and Beta vulgaris were comparable under similar conditions. V. unguiculata and C. olitorius performed better than Beta vulgaris indicating an opportunity to improve productivity under drought conditions.