SEASONAL-VARIATION IN HYDROCHLORIC-ACID, MALIC-ACID, AND CALCIUM-IONSSECRETED BY THE TRICHOMES OF CHICKPEA (CICER-ARIETINUM)

The concentrations of malate, calcium ions, hydrogen ions, and chlorid e ions were measured in secretions collected between June 1991 and May 1992 from the secretory trichomes of chickpea (Cicer arietinum L.). T he average malate concentration was 114 mM and varied from 2 to 287 mM , the average chloride ion concentration was 177 mM and Varied from 68 to 355 mM,and the average calcium ion concentration was 0.82 mM and V aried from 0.24 to 1.97 mM. The variability in malate, chloride ions, and calcium ions closely followed the sinusoidal variation in the amou nt of solar radiation per day throughout the year (Riverside, CA, USA) . Also, 77% of the variation in malate concentration, 51% of the varia tion in chloride ion concentration, and 67% of the variation in calciu m ion concentration in collected secretions was directly dependent on the day of the year. In addition, the average hydrogen ion concentrati on was 299 mM, which corresponds to a pH of 0.52. Although the concent ration of hydrogen ions varied from 195 mM (pH 0.71) to 417 mM (pH 0.3 8) throughout the year, the variation did not follow any clear pattern with respect to the day of the year. These data suggest that malate, chloride ion, and calcium ion secretion are linked to the amount of da ily sunlight and to the day of the year while the pH of secretions is not directly linked to light level.