Stomatal Characteristics at Different Ploidy Levels inCoffeaL.

Abstract

Abstract Stomatal frequency, epidermal cell frequency, stomatal guard cell length and stomatal index were examined at different ploidy levels in Coffea . In general, stomatal and epidermal cell frequency per unit leaf area decreased while stomatal guard cell length increased with an increase in ploidy. The reduction in stomatal frequency at higher ploidy levels was mainly a result of larger epidermal cells. In the case of C. canephora (cultivar S.274) a significant reduction in stomatal frequency was noticed from diploid to tetraploid level which was due to both larger epidermal cell size and less stomatal differentiation at the tetraploid level. Besides the effect of ploidy on stomatal frequency and guard cell length, genotypic differences in stomatal frequency and stomatal guard cell length were also observed among cultivars of the same ploidy level. Although variation in stomatal frequency among cultivars was found to be associated with the difference in stomatal to epidermal cell ratio, variation in guard cell length was attributed to differential genetic architecture. In the present study a highly significant positive correlation ( r =0.82) between stomatal and epidermal cell frequency and high negative correlations between stomatal frequency and guard cell length ( r =-0.91) and epidermal cell frequency and stomatal guard cell length ( r =-0.93) were obtained. The study also indicated that stomatal frequency can be predicted with 83 and 87% accuracy, respectively, by measuring stomatal guard cell length in coffee.