Osmotic Adjustments and Associated Water Relations of Clonai Tea (Camellia sinensis (L.)

Abstract

Soil moisture stress associated with high saturation vapour pressure deficits during drought causes adverse impacts on water economy of tea plants. Transpiration rate and stomatal conductance are generally used as indices for screening tea clones for drought resistivity.However, accumulation of osmotically active solutes, leading to osmotic adjustments play a major role in drought tolerance.Green house studies were conducted to rank recently recommended tea clones for drought tolerance. Feasibility of using osmotic adjustments as a criterion for drought tolerance was studied and identified as a key factor. The treatments consisted of 5 TRI '3000' series clones, 5 TRI '4000' series clones and TRI 2025 which is a well known drought tolerant clones. Artificial induction of drought modified transpiration rates and diffusive resistance resulted in lower leaf water potential at zero turgor, and were higher in most of TRI '4000' series clones while that of TRI '3000' series clones were approximately similar to that of TRI 2025/6. Henee, TRI '3000' series clones can also be considered as drought tolerant clones.Wider osmotic adjustments together with more negative water potential at zerb turgor of TRI '4000' series clones revealed more capability to tolerate dry conditions than the other tested clones.