Seasonal variation in hydrochloric acid, malic acid, and calcium ions secreted by the trichomes of chickpea {Cicer arktinum)

The concentrations of malate, calcium ions, hydrogen ions, and chloride ions were measured in secretions coliected hetween June 1991 and May 1992 from the secretor\ trichomes of chickpea (Cicer arietinum L.|. The average maiate cisncentration was 114 mM and \ aried from 2 to 2K7 mM. the average chloride ion concentration «as 177 mM and varied trom 68 to 355 mM, and the average calcium ion concentration was 0,82 xnM and varied from 0.24 to 1.97 myW. The variabilits in maiate. chloride ions, and calcium ions closely followed the sinusoidal variation in the amount of solar radiation per da\ throughout the year (Riverside, CA. USAl. Also, 77'7r of the variation in maiate concentration, 5l'>r ofthe variation in chloride ion concentration, and 67% of the variation in calcium ion concentration in collected secretions was directh dependent on the day ofthe year. In addition, the average hydrogen ion concentration was 299 m,W, which corresponds !o a pH of 0,52. Although the concentration of hydrogen ions varied from 195 mM (pH 0.7!) to 4i7 mM (pH 0.38) throughout the year, the \ ariation did not tollow any clear pattern with respect to the da\ of the year. These data suggest that maiate, chloride ion, and calcium ion secretion are iiniied to the amount of daily sunlight and to the day of Ehe year while the pH of secretions ts not directh linked to light level.