Evaluation of the Effect of Calcium Nitrate on Growth Characteristics of Selected Pomegranate Genotypes in Saline Conditions

To evaluate the effect of calcium nitrate on some growth characteristics of selected pomegranate (Punica granatum) genotypes, a factorial experiment was carried out based on randomized complete block design (BCRD) with 3 replications at Chahafzal Station of the National Salinity Research Center of Iran, in 2019-2020. Two factors were studied: genotypes at 6 levels (Post-Siyah Ardakan, Rabab Neyriz, Chah Afzal, Narak Lasjerd Semnad ,Vahshi Babolsar, and Malas Yazdi) and calcium nitrate at 3 levels (0 (control), 50 and 100 kg/ha), using irrigation water salinity of 9±0.5 dS/m.  The results showed that type of genotype and levels of calcium nitrate affected morphological and physiological characteristics and concentration of nutrient elements in leaves. The highest and lowest necrotic leaves (12% and 2%), leaf surface ratio (1845 and 879 mm2/g dry weight), relative water content (80.83% and 52.40%), total chlorophyll (11.4 and 6.45 mg/g fresh weight), potassium content (0.378% and 0.322%) and lowest and highest sodium content (1.88% and 2.75%), relative ions leakage (14.85% and 30.02%) and sodium to potassium ratio (0.118 and 0.197) was observed in Chah Afzal with 100 kg/ha of calcium nitrate and Rebab Niriz without calcium nitrate application, respectively. Overall, Chah-Afzal was recognized as the most tolerant genotypes to saline condition. This genotype showed more suitable growth than the other genotypes by maintaining its growth characteristics and increasing potassium uptake compared to sodium. Also, the results showed that application of 100 kg/ha of calcium nitrate at the beginning of the growing season significantly improved the growth characteristics and reduced the harmful effects of sodium in all studied genotypes.