Saffron-pumpkin/watermelon: A clean and sustainable strategy for increasing economic land equivalent ratio under limited irrigation

Abstract

Generally, from the onset of dormancy to flowering, saffron farms are free of vegetation. Therefore, nutrients loss due to soil erosion, increased soil temperature and reduced land use efficiency are the most obvious problems of sole saffron cultivation, occurring over this period. Herein the intercropping advantage of saffron with watermelon or pumpkin and its effects on growth, yield and economic land equivalent ratio under limited irrigation were evaluated as a three-year field experiment (2014–2017) with a randomized complete blocks design arranged in factorial with three replicates. In this study, limited irrigation regimes on pumpkin and watermelon (14 and 28 days intervals) and cropping systems (saffron, pumpkin, watermelon, saffron + pumpkin and saffron + watermelon) were considered as the first and the second factors, respectively. Except for 2014, the individual effects of irrigation scheme and cropping systems on flower number and dried stigma yield were significant. In 2015, 2016, in comparison to saffron monoculture, intercropping significantly increased flower number and dried stigma yield. Moreover, in these years, increase in irrigation interval from 14 to 28 days significantly reduced average fruit weight in pumpkin and watermelon. The maximum land equivalent ratio and economic land equivalent ratio of saffron were found in saffron-pumpkin intercropping system with 14 days irrigation interval. Intercropping could positively affect saffron corms growth and N and P concentrations in the corms. In sum, considering the water shortage in arid and semi-arid regions, saffron-pumpkin or saffron-watermelon intercropping increases land efficiency and improves farmers’ income during perennial life cycle of saffron.