A MICROSCOPIC TECHNIQUE TO MEASURE MESOPHYLL SUCCULENCE

Mesophyll succulence (S_m), the ratio of water content to chlorophyll content of a cell or tissue, has been proposed as an index of CAM potential. In plant tissues where all cells contain chloroplasts, S_m may be measured easily. If water tissue (water-storing parenchyma lacking chloroplasts) is present, however, severe technical difficulties arise. We have developed a comparable index, morphological mesophyll succulence (S_mm), which allows rapid determination of vacuole to chloroplast volumes in cells. There is a high correlation between the results obtained by these two techniques. Advantages of the microscopic technique include: more rapid determinations, fewer equipment needs, ability to be applied in the field, and no need to physically separate water tissues from photosynthetic tissues.