Effect of irrigation water salinity, manure application and planting method on qualitative compounds of saffron (Crocus sativus L.)

The objective of the present study is to investigate the effects of irrigation water salinity, cow manure levels and different planting methods on saffron quality compounds including crocin (coloring strength), picrocrocin (bitterness) and safranal (aromatic strength). A split-split plot arrangement was conducted in complete randomized block design with irrigation water salinity levels (0.45 (fresh water, S1), 1.0 (S2), 2.0 (S3) and 3.0 (S4) dS m-1) as the main plot, cow manure levels (30 (F1) and 60 (F2) Mg ha-1) as the sub plot and planting method (basin (P1) and in-furrow (P2)) as the sub-sub plot in three replications. Results showed that the saffron coloring strength, bitterness and aromatic strength in higher salinity level decreased by 9, 1 3 and 18% in comparison with the lowest salinity level, respectively. However, saffron (stile/stigmas) yield declined significantly as about 42% by increasing water salinity to highest level. The saffron crocin and picrocrocin concentration for the in-furrow planting method were significantly higher than the basin planting method by about 4 and 8%, respectively. Higher application rate of cow manure (60 Mg ha-1) did not promote the saffron quality compounds. Furthermore, planting methods showed no significant effect on saffron aromatic strength. Correlation analysis indicated that saffron quality compounds showed negative relationship with leaf calcium, sodium and chloride and positive relationship with leaf phosphorus, nitrogen and potassium at 0.01 and 0.05 significant levels, Furthermore, a positive correlation between crocin and picrocrocin and saffron yield components (leaf dry matter, corm, flower and saffron yields) was observed; however, there was no significant correlation between safranal and yield components. Generally, the saffron quality compounds variations were concurrent with the saffron quantity variations.