Physiological optimality, allocation trade-offs and antioxidant protection linked to better leaf yield performance in drought exposed mulberry

Abstract

Background: Mulberry (Morus spp. L.), usually linked to silkworm rearing, is now considered as a potential forage for livestock feeding and has great potential in world agriculture. Trait-based investigations for leaf yield stability in mulberry under water stress have not been studied extensively. The present study aims to identify candidate traits conferring leaf yield stability in mulberry under drought.

Results: Four popular, indigenous mulberry cultivars (Morus indica L. cvs AR-12, K-2, M. Local and V-1) were investigated. Low leaf temperature (T(l)), higher internal/ambient CO(2) ratios (C(i)/C(a)), greater stomatal conductance to CO(2) (g(s)) and stability in photosystem II efficiency were associated with better net photosynthetic rates (P(n)) in V-1, generating maximum leaf yield when compared to other drought-exposed cultivars. Increased accumulation of foliar α-tocopherol and ascorbic acid-glutathione pool, associated with higher carotenoids, proline and glycine betaine, facilitated lower lipid peroxidation and better leaf yield in V-1 under drought.

Conclusion: Minimal plasticity in photosynthetic gas exchange traits and better quantitative growth characteristics were attributed to leaf yield stability under drought. Lower photoinhibition, stabilized photochemistry, effective osmoregulation and enhanced activity of foliar antioxidants extensively contributed to drought tolerance and higher leaf yield in mulberry.