Effects of drought and heat stress on physiological characteristics in alfalfa leaves

Abstract: Leaf chlorophyll content, relative conductivity and water saturation deficit were determined in six gernplasms of alfalfa when subjected to heat stress and rehydrated condition. The results showed that as heat stress prolonged: 1) the water saturation deficit increased in all gernplasms; 2) the relative conductivity increased except accession 16 and 15 decreased in the eighth day; 3) leaf chlorophyll content decreased except accession 15 increased in the eighth day. Based on the results, present study suggested that accession 28 performed better than the other varieties in heat resistance, while accession 26 was relative worse. Correlation analysis showed that water saturation deficit significantly negatively correlated with chlorophyll content but positively correlated with relative conductivity. This implied that water deficit severely affected the integrity of cell membrane and lead to chlorophyll content inhibition.