Growth regulation of Desmostachya bipinnata by organ-specific biomass, water relations, and ion allocation responses to improve salt resistance

Abstract

Salt resistance strategies in Desmostachya bipinnata may be a function of coordinated organ specific responses for growth and developmental stages. It may provide clues to improve salt tolerance in conventional crops. The effects of NaCl concentrations (100, 200, 300 and 400 mM) on growth, water relations, organic compound (proline and sugar) accumulation, ion-flux and nutrient selectivity both in root [adventitious (RA) and mature (RM) root] and shoot [juvenile (LJ) and adult (LA) leaves] organs were investigated. Decreases in biomass were observed under saline treatments higher than 100 mM NaCl. The lower amount of biomass is considered to be a survival strategy under harsh conditions due to reallocation of energy in the plant. D. bipinnata regulated water flux (OP, osmotic potential, in the following order: LJ > LA > RM > RA) to allow water uptake from soil under hyperosmotic conditions. Na+ was largely accumulated in roots followed by LA and LJ. This ion excluding strategy is common in monocots to protect photosynthetic tissues. Salt-treated plants retained more Ca2+ and Mg2+ in roots than in shoots, while K+ allocation was not affected by salinity. This may be due to selective transport in the case of K+ and increasing use efficiency for Ca2+ and Mg2+. Whole plant responses generally are organ-specific based on salinity concentrations. Our findings suggest that different organs of D. bipinnata coordinated with each other for biomass partitioning, OP gradient, Na+ distribution, K+ selective transport, nutrient use efficiency, and sugar and proline allocation to achieve better yields in moderately saline areas for fodder/forage production.