PRECISION STRESSING BY SUPPLEMENTAL Ca AND BACILLUS SUBTILIS FZB24 TO IMPROVE QUALITY OF LETTUCE UNDER PROTECTED CULTIVATION
Tipburn of lettuce (Lactuca sativa L.) is a severe problem causing severe losses in many lettuce-growing areas. In a commercial peat pot experiment under green house conditions in 2007, lettuce plants were exposed to the possible causes of tipburn, i.e., salinity (3.0 dS m-1), late N application and high night temperature during head formation. The effect of two improvement strategies, i.e., inoculation of root rhizosphere with Bacillus subtilis FZB24 and supplemental Ca foliar sprays were evaluated. Results showed that high night temperature ranked first in reducing total yield (g/head) followed by salinity and late N application. However, dry matter percentage was not altered by any of the studied stress treatments. Salinity increased rate of tipburn most, followed by high night temperature and late N application, had the least effect compared to control (non-stressed plants). NO3 and Ca contents were decreased by salinity, while N was increased by high night temperature and late N application. Both supplemental Ca and inoculation with Bacillus subtilis showed a positive effect in increasing Ca content in outer leaves of the saline-stressed plants and control treatments. Inoculation with Bacillus subtilis was better than Ca foliar sprays in increasing Ca content in inner leaves. The supplementary application of Ca was better for alleviation of tipburn in lettuce compared to non-treated control and even application of Bacillus subtilis FZB24. Total yield (g/head) was increased by inoculation with Bacillus subtilis FZB24, while no significant effect occurred from supplemental Ca.
Saleh, S.A. (2009). PRECISION STRESSING BY SUPPLEMENTAL Ca AND BACILLUS SUBTILIS FZB24 TO IMPROVE QUALITY OF LETTUCE UNDER PROTECTED CULTIVATION. Acta Hortic. 824, 297-302
greenhouse, salinity, late N application, high night temperature, nutrient solution, Lactuca sativa