Physiological response of castor (Ricinus communis L.) to the application of biofertilizers and superabsorbents under water deficit stress conditions

Results and discussion Based on the results of the combined analysis of the variance of the data, there was a significant difference in was observed between the two years in terms of malondialdehyde content. There was a significant difference between the irrigation levels in terms of the effect on all traits of the probability level of 1%. The interaction effect of year and irrigation was significant only on leaf proline content at the level of 1% probability. There was a significant difference between the biofertilizer treatments and the interaction effect of biofertilizer on irrigation and superabsorbent levels in terms of the effect on all traits at the level of one percent probability. The interaction effect of irrigation with superabsorbent on chlorophyll a and b content and soluble sugar content at 1% probability level and on proline content and protein percentage at 5% probability level was significant. Between treatments of biofertilizer with superadd interaction in terms of the effect on chlorophyll b content, soluble sugar, proline content, malondialdehyde content, and protein percentage at the level of 1% percent and in terms of the effect on chlorophyll content, carotenoids and catalase activity in 5% probability level There was a significant difference. The results showed the highest chlorophyll a (23.00 mg g-1) and b content (14.93 mg g-1) as well as carotenoids (30.39 mg g-1) and the lowest amount of soluble sugar (113.33 micromol g-1 fresh weight), catalase (32.97∆A240 mg-1 protein), malondialdehyde (132.44 nmol g-1FW) and protein percentage (4.69%) were assigned to with Citrobacter treatment and irrigation after 70 mm of evaporation. Also, the highest soluble sugar content (131.42 micromol g-1 FW), proline (65.91 micromol g-1 FW), protein (11.48 %) was assigned to the treatment with Azosprilium + Citrobacter and irrigation after 160 mm of evaporation. In this study, the use of superabsorbent in the irrigation treatment of 70 mm evaporation had the highest chlorophyll a (21.29 mg g-1) and b content (12.78 mg g-1) and the lowest amount of soluble sugar (112.50 micromol g-1 FW), proline (26.50 micromol g-1 FW), catalase (35.99 ∆A mg-1 protein) and protein percentage (5.00%), While the highest soluble sugars content (129.12 micromols g-1 FW), proline (58.70 micromols g-1 FW), malondialdehyde (159.71 nmol g-1 FW), and protein (10.37 %), was observed in the treatment of superabsorbent application along with irrigation after 160 mm. In this study, the simultaneous application of superabsorbent and inoculation with azospirlium showed the highest chlorophyll a (22.25 mg g-1), b content (13.79 mg g-1), carotenoid (29.02 mg g-1), protein (7.99%) and the lowest content of catalase enzyme (39.58 ∆A240 mg-1 protein), The highest soluble sugar content (122.88 micromol g-1 FW) and the lowest amount of malondialdehyde (141.82 nmol g-1FW) were detected in the treatment of superabsorbent application with Citrobacter. Conclusion In this study, water deficit had an adverse effect on the physiological properties of castor oil. However, the use of biofertilizers and superplasticizers by improving biochemical and antioxidant properties was able to moderate the effect of drought stress on physiological properties and stabilize photosynthetic pigments, and the stability of photosynthetic pigments can improve photosynthetic properties and plant growth under water deficit conditions.