Saffron Daughter Corms Formation, Nitrogen and Phosphorous Uptake in Response to Low Planting Density, Sampling Rounds, Vermicompost and Mineral Fertilizers.

Higher planting densities increase flower yield of saffron during the initial years; however, increase in population may have a negative effect on daughter corms, through increasing competition for nutrients. Accordingly, lower densities result in more desirable daughter corms for future planting. To investigate the effect of planting density, vermicompost and mineral fertilizers on daughter corms formation, and nitrogen (N) and phosphorus (P) content in the corms during different phenological stages, a three-year field experiment was conducted as factorial-split layout based on randomized complete block design with three replications, at Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. The experiment consisted of 12 main plots [planting density (30, 60, 90 and 120 corms m−2) × fertilizer sources (vermicompost 10.2 t ha−1, mineral fertilizer including N 225 kg ha−1 + P 129.08 kg ha−1 and control)] and 15 subplots (15 sampling rounds; during the first, second and third growing seasons). During all stages of sampling, N and P content in large-sized daughter corms was significantly higher compared with middle and large-sized daughter corms. Application of vermicompost significantly increased the number, weight, N and P contents of medium and large daughter corms per plant than mineral fertilizer. Increase in plating density caused a significant reduction in number, weight, N and P content in the medium and large sized daughter corms per plant. Overall, the results suggest that lower densities and vermicompost application should be scheduled in mother corms production programs. [ABSTRACT FROM AUTHOR]