Does nutrient and irrigation managements alter the quality and yield of saffron (Crocus sativus L.)?

Increasing the saffron quantity and quality is essential and should be considered to achieve the desired performance. In this regard, to study the effect of nutrient and irrigation management on the quality and yield of saffron, an experiment was carried out at the research station, the Ferdowsi University of Mashhad, Iran, in 2013–2015. The study was performed as a split-split plot based on a Randomized Complete Block Design with 18 treatments. Experimental factors were: 1- superabsorbent (S.A.) [application and non-application (non-S.A.)], 2- irrigation intervals [every two, three, and four weeks], and 3- nutrient management [humic acid, mycorrhiza (Glomus intraradices) and control]. Among all treatments, the application of S.A. increased on average 61% fresh saffron flower and dry stigma yields in both growing seasons. S.A. + four weeks irrigation intervals + humic acid were increased number of flower, dry stigma yields (175.33 per m2 and 7.472 kg.ha-1, respectively), and water productivity of irrigation of saffron stigma (2.138 g.ha-1) in 2015. The use of S.A. and humic acid compensated for water shortage and increased stigmas' yield. Furthermore, the maximum L observed in S.A. + three weeks irrigation intervals + humic acid (32.44). Among all treatments, the lowest amount of b value and Hue was observed in shorter irrigation intervals; so, application of S.A. + two weeks irrigation intervals + humic acid resulted in the minimum amount of Hue (−0.1783) that was a desirable trait. The maximum crocin and picrocrocin obtained in S.A. + three weeks irrigation intervals + mycorrhiza (225.9 A4401% and 86.58 A2541%, respectively) and the highest safranal content observed in S.A. + four weeks irrigation intervals + humic acid (47.03 A3301%). In general, it seems that the application of humic acid, mycorrhiza, S.A., and longer irrigation intervals can significantly increase the quality and yield of saffron.