Common Physiological Disorders of Lettuce (Lactuca sativa) Found in Swaziland: A Review
Lettuce is a very important cool season leaf/salad vegetable widely consumed in Swaziland and Southern Africa in general. It contributes immensely to nutritional and food security and has a short growth cycle making it a climate smart vegetable. Despite its immense importance locally not much research has been apportioned to this vegetable among other aspects identification and alleviation of physiologically disorders of leaf or head lettuce. Lettuce physiological disorders are not caused by pathogens, viruses, insect pests, nematodes or other biological agents but are caused by environmental factors or nutritional excesses, deficiency ’exacerbated or alleviated by genetic make up of lettuce cultivars. The objective of this study was to identify various physiological disorders affecting lettuce in the various agroecological zones of the Kingdom of Swaziland. The various physiological disorders of lettuce encountered in this study included bolting, brown rib, ribbiness/puffy heads, rib discoloration, russet spotting, brown stain and pink rib. Various ways of alleviating a specific disorder are suggested including genotype by environment by management (GXEXM) manipulation.