Corm weight or number per unit of land: Which one is more effective when planting corm, based on the age of the field from which corms were selected?

چکیده مقاله

In this study the best corm weight (4–6 g as small-sized and 6–8 g as medium-sized corms) and density (50, 75 and 100 corm m−2) was determined for saffron fields in different ages (1, 2 and 3 years-old). For this purpose, a factorial experiment based on a randomized complete block design with 3 replications was performed during 3 growing seasons from autumn 2015 up to spring 2018, in Ferdowsi University of Mashhad research site. The highest flower number, flower and stigma yields in one- (21.7 flower per m2, 67 and 0.97 kg ha-1, respectively) and two-years old (70.4 flower per m2, 214 and 2.92 kg ha-1, respectively) fields were obtained from medium-sized and density of 100 corms per m2, while in three-years old field, their maximum values (101 flower per m2, 302 and 4.09 kg ha-1, respectively) were gained when medium-sized corms were planted at density of 75 corms per m2. The priority of corm weight in lower corm densities was higher, so that, flower yield in medium sized corms was 2.43, 1.87 and 1.62 times more than small-sized corm in 50, 75 and 100 corms per m2 densities, respectively. Corm weight was prior to corm density, so that, planting of 3.5-ton ha-1 medium-sized corm with density of 50 corms per m2, was produced more flower than planting of 5-ton ha-1 small-sized corm with density of 100 corms per m2 (47.5 vs. 36.7 flower per m2 and 1.99 vs. 1.50 kg ha-1 dry stigma). Corm weight preference in one- and two-years old fields were more than three-years old filed, where larger corms increased flower yield by 1.94, 2.15 and 1.75 times compared with small-sized ones in mentioned fields, respectively. Mean replacement corm weight and number of large replacement corms (>9 g) decreased when small-sized mother corms were planted and when the farm became elderly. The highest replacement corm yield (52.8-ton ha-1) and number (2034 NO. m−2) were obtained when medium-sized mother corms were planted at density of 100 corms per m2 and remained in field for three years. Overall, the corm harvesting from one-year-old field was preferable in terms of mean corm weight and production of larger replacement corms.