Effect of corm harvesting year on agronomic criteria, daughter corm yield and flower yield of saffron (Crocus sativus L.)

Saffron (Crocus sativus L.) is a sterile geophyte plant that propagates vegetatively by means of a corm formation. During each growing season, saffron propagates by daughter corms produced from the mother corm. The daughter corms are formed above the mother corm. The plant can be maintained up to 8–10 years. In order to study the effect of corm harvesting year on daughter corm and flower yield of saffron, a four- year experiment was conducted at Research Field, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran during four growing seasons of 2015-2016, 2016-2017, 2017-2018 and 2018-2019. Treatments were four corm harvesting years that considered as one, two, three and four years aged plots. Studied traits were flower numbers per m2, fresh weight of flower per m2, dried weight of stigma per m2, number of daughter corms per m2, dried weight of daughter corms, daughter corm diameter and number and weight of daughter corms in five weight groups such as <4, 4-8, 8-12, 12-16 and >16 g. Based on the results, the highest production gains in flower numbers (67.1 flowers per m2), flower fresh weight (32.31 g.m-2) and stigma dried weight (0.761 g.m-2) were observed in the second harvesting year. Also, the maximum daughter corm number and daughter corm yield were recorded for the third harvesting year with 189.5 corms.m-2 and 603.91 g.m-2, respectively. Although the progeny corm number continued to rise each year, at the third generation corm production was dominated by corms below 12 g and this suggests a need to lift the corms and replanting at the beginning of the fourth year.