Titratable Acids in Opuntia ficus-indica L

Abstract

Accumulation of acidity in spiny and spineless Opuntia joints fluctuated daily due to crassulacean acid metabolism (CAM) in Golan Height and coastal plain. The acidity reached higher concentrations in the young joints, especially during early morning hours, before the plants were exposed to sunlight. Changes in acidity were more pronounced in the chlorenchyma than in the water-accumulating tissues. These findings provide information on the rate and time of photosynthesis of these plants and may enable the feeding of livestock on Opuntia, while acid levels taken in by livestock are kept low to reduce a cause of diarrhea. The acidity is lower on sunny warm days, during late afternoons, in shriveled, old joints which had been exposed to full sunlight or were excised and stored in light. It may, therefore, be better to let cattle feed on the shriveled Opuntia before the start of the rainy season and use shrubs such as Atriplex halimus, which is better suited after onset of the first rain, as complementary perennial feed.