SEED BIOPRIMING WITH SALINITY TOLERANT ISOLATES OF TRICHODERMA HARZIANUM ALLEVIATES SALT STRESS IN RICE: GROWTH PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS
L. Rawat, Y. Singh, N. Shukla, J. Kumar
A greenhouse experiment was conducted to examine the effect of seed biopriming with five salinity tolerant isolates of Trichoderma harzianum on the response of rice (Oryza sativa L.) to different salt stress levels. One factor was different Trichoderma treatments (Th-13, Th- 14, Th-19, Th-33 and Th-50) and the second factor was four levels of salt stress viz., 0, 70, 150 and 240 mM NaCl. Growth, physiological and biochemical parameters were determined to characterize salt tolerance. Salt stress adversely affected the studied parameters. However, the data revealed that Trichoderma treatments alleviated the stress condition and significantly increased length and fresh weight of shoot and root, number of leaves, leaf area, photosynthetic rate, chlorophyll fluorescence, chlorophyll content and soil plant analysis development (SPAD) value in comparison to control at all stress levels. Trichoderma treatments also resulted in the alleviation of oxidative damage, as indicated by the decrease of malondealdehyde content in comparison to control. Seedlings raised from seeds bioprimed with Th- 14 had significantly higher proline, membrane stability index and phenol content than other treated or untreated seeds under both non-saline and saline conditions. Besides, linear regression showed that the photosynthetic rate had a significant positive relationship with the number of leaves, leaf area, chlorophyll fluorescence, chlorophyll content and SPAD value, but no relation with leaf water content. Results indicate the potential of using salinity tolerant Trichoderma isolates through seed biopriming for reducing the deteriorating effects of salinity, with Th-14 giving the most consistent effect under the present experimental material and conditions.