Physiological response and polyamines content of cumin (Cuminum cyminum L.) to water irrigation quality in the application of chemical and organic fertilizers

According to the necessity of using the substances reducing the harmful effects of salinity stress in areas with saline water and soil, and providing major plant nutrients through fertilizers, a split-plot experiment in a randomized complete block design with three replications was conducted at the Research Farm of Zabol University during 2012. Two levels of irrigation water quality (0.59 and 4.180 dS.m-1 EC) were in the main plots, and four levels of fertilizer (control, chemical fertilizer in the ratio of 80:40:30 kg.ha-1 from CO (NH2)2, Ca(H2PO4) and K2SO4 respectively, 40 ton.ha-1 manure and combination of fertilizers in half amount of mentioned) were in sub-plots. Results showed that saline water irrigation (EC: 4.180 dS.m-1) increased the activity of CAT and APX antioxidant enzymes, and other enzyme activity was reduced. In addition, the content of putrescine (Put), spermine (Spm) and spermidine (Spd), proline and carbohydrates, sodium and photosynthetic pigments in cumin (Cuminum cyminum L.)leaves increased. A separate application of NPK-fertilizer and manure showed no significant difference for physiological traits except spermine content, proline, sodium, and potassium. The combined application of NPK-fertilizer and manure was more efficient in reducing the antioxidant enzymes activity of CAT and GPX and enhancing the content of spermidine, proline, photosynthetic pigments, and potassium. The potassium content in combined treatment (581 ppm) compared with the separate application of NPK-fertilizer and manure increased 17.61 and 18.53 percent, respectively. According to the results of this study, in order to reduce the unilateral use of chemical fertilizer and supply plant nutrients required in salinity, NPK fertilizer with 40:20:15 kg.ha-1 ratios with 20 ton.ha-1 manure is recommended.