Stomatal Density as a Selection Criterion for Developing Tea Varieties with High Physiological Efficiency

Stomata, the small opening in leaf connecting plant with atmosphere, play pivotal roles in global water and carbon cycles. Stomata regulate the two key important physiological functions viz. photosynthesis and transpiration and thus are crucial for performance of crop species in changing climatic conditions. Although environmental factors influence the density and size of stomata, the genetic control of this character is evident. High variation for this character is reported from different crop species and thus improvement of this character is possible through appropriately designed breeding strategy. In tea, stomatal density varied from 44.67 mm-2 to 108 mm-2 and this character exhibited a significant and positive correlation with photosynthetic rate (Pn) and water use efficiency. A high value for heritability and genetic advance was detected for this character in tea, indicating its tight genetic control. Thus stomatal density may be an important selection criterion and development of physiologically efficient tea clones and seed varieties may be possible by improving stomatal density through a suitably designed breeding strategy.