Effects of Aminol-Forte Fertilizer Spraying on Physiological and Biochemical Responses of Pomegranate cv. Naderi under Drought Stress Conditions

Pomegranate (Punica granatum L.) belongs to the Punicaceae family and grows in subtropical and Mediterranean climates. Nowadays the widespread usage of inorganic fertilizers has increased and so people concern about their health. The use of organic fertilizer instead of inorganic fertilizers is one of the methods of preserving health. Pomegranate is one of the most important products of Iran. This fruit plant is cultivated in some regions in arid and semi-arid areas. Due to the long growing season of pomegranate, droughtstress is one of the main limiting factors in the development of pomegranate orchards in Iran. Utilization of amino acids can help to increase efficiency and improve the quality of the fruit under environmental stress. Thus, this study aims to findany possibility to increase the production and quality of the fruit during the drought. The goalof this study was to study the effect of organic Aminol-Forte fertilizer on physiological and biochemical responses of pomegranate cv. Naderi under drought stress conditions.
This research was carried out in AbShirin field located on the old road 40 km from Qom-Kashan during 2011. Asplit plot experiment based on randomized complete block design was conducted with two factors, irrigation treatment in three levels (100% required water, 75% required water and 50% required water) and Aminol-Forte fertilizer treatment in four levels (0, 2, 3 and 4 ml/l). Spraying was conducted in four stages (pre-anthesis, after fruit set, fruit growth andtwo weeks per-harvest). In the end of the experiment, chlorophyll index, soluble sugars, insoluble sugars, proline, canopy degree and stomatal conductance were measured. Statistical analysis was performed using SPSS 17 program. Means were separated according to the Duncan’s multiple range test (DMRT) at 0.01 level of probability.
Analysis of variance of Aminol-forte fertilizer spraying on physiological and biochemical responses of pomegranate cv. Naderi under drought stress conditions showed that between irrigation treatment for chlorophyll index, proline and stomatal conductance were significant at 1% level of probability, and at 5% level of probability soluble sugarand insoluble sugar and canopy degree were significant. Fertilizer treatment at 1% level of probability was significant for proline and at 5% level of probability was significant for soluble sugars. Interaction was significant for soluble sugars, proline and canopy degree. Means showed that by increasing fertilizer level, soluble sugars content, proline and stomatal conductance significantly increased insoluble sugars and chlorophyll index decreased insignificantly. By decreasing irrigation levels, chlorophyll index, soluble sugars and proline significantly increased, meanwhile insoluble sugars and stomatal conductance significantly decreased. The highest chlorophyll index (65.44 SPAD) and the lowest chlorophyll index (56.48 SPAD) were obtained in 75% required water with 2 ml/l of fertilizer level and 100% required water with 3 ml/l of fertilizer level, respectively. The highest soluble sugars (14.94 mg/g) and the lowest soluble sugars (11.64 mg/l) were obtained in 50% required water with 0 ml/l of fertilizer level and 100% required water 2 ml/l of fertilizer level, respectively. The highest insoluble sugars (9.99 mg/g) and the lowest insoluble sugars (6.82 mg/l) were measured in 100% required water with 3 ml/l of fertilizer level and 50% required water with 2 ml/l of fertilizer level, respectively. The highest proline content (2.51μmol/l) and the lowest proline content (1.05μmol/l) were obtained in 50% required water with 4 ml/l of fertilizer level and 100% required water with 0 ml/l of fertilizer level, respectively. The highest canopy degree (-7.31˚c) and the lowest canopy degree (-9.38˚c) were measured in 50% required water with 4 ml/l of fertilizer level and 100% required water with 4 ml/l of fertilizer level, respectively. The highest stomatal conductance (38.23 mmol/m2/s) and the lowest stomatal conductance (9.7 mmol/m2/s) were obtained in 50% required water with 2 ml/l of fertilizer level and 100% required water with 3 ml/l of fertilizer level, respectively.
By increasing the level of Aminol-Forte fertilizer from 0 to 4 ml/l, soluble sugars content, proline and stomatal conductance significantly increased meanwhile insoluble sugars and the chlorophyll index decreased. Drought stress increased soluble sugars content, chlorophyll index, canopy degree and proline but, insoluble sugars and stomatal conductance decreased. According obtained results, it can be said, spraying of Aminol-Forte fertilizer containing amino acid could significantly reduce the negative effects of drought stress. In this study, the best results in terms of stress and no stress were obtained in 3 and 4 ml/l of Aminol-Forte fertilizer.