the effect of irrigation intervals and intecropped marjoram (origanum vulgare) with saffron (crocus sativus) on possible cooling effect of corms for climate change adaptation

in order to study the effect of irrigation intervals and intecropped marjoram (origanum vulgare) (as a shading crop for reducing the possible effects of soil warming due to climate change) on the growth and yield of saffron (crocus sativus), a field experiment was conducted as split-plot based on randomized complete block design with three replications, during 2008 and 2009 at the agricultural research station of ferdowsi university of mashhad, iran. three irrigation intervals (every 7, 14, and 21 days) and three planting combinations (1:0 (pure stand of saffron), 1:1 (one row of saffron + one row of marjoram), 2:1 (two rows of saffron + one row of marjoram) and 3:1 (three rows of saffron + one row of marjoram)) were allocated to main and sub plots, respectively. results indicated that the simple effects of irrigation interval and planting combination on the flower number, flower weight and economical yield of saffron were significant (p≤0.01). also, the interaction effects between irrigation interval and planting combination on the flower number, flower weight and economical yield of saffron were significant (p≤0.01). the highest and the lowest of saffron economical yield were observed in the irrigation intervals with every 14 (0.27 g.m-2) and 7 days (0.09 g.m-2), respectively. also, the maximum and the minimum economical yield of saffron were observed in 1:1 (0.20 g.m-2) and pure stand of saffron (0.15 g.m-2), respectively. with increasing irrigation intervals, the growth characteristics and economical yield of saffron were enhanced. it seems that the intercropped saffron with marjoram increased the flower number and economical yield of saffron due to decreasing soil temperature which could be regarded as an alternative to the possible effect of soil warming for climate change adaptation.