Determination of the most suitable planting date and garlic ecotype (Allium sativum L.) in South Kerman

Garlic (Allium sativum L.) belongs to the Liliaceae family and has more than 800 species around the world (Fritsch et al., 2010). This plant after onion is the second and most consumed alium genus, which has high nutritional value due to its minerals. Asexual propagation of garlic during the centuries may resulte in a genetic restriction. However, the study of ecotypes shows that phenotypic variation is significant in size, color, leaf length, growth habits and agronomic traits such as stress and drought tolerance. In according to Iran was the most important exporting country at the world in the past, the study of ecotypes to meet the demands of domestic markets as well as the export of this product is a necessity. Due to the fact that in south of Kerman province for cultivation and production of garlic from different ecotypes of the country, incompatibility of some ecotypes has caused a lot of problems for the farmers of the region. On the other hand, different planting dates (September to December) it is common in this region where the best ecotypes and planting dates have a great importance for obtaining high yield and can be of great help to the farmers of the region.

In order to achieve the best ecotypes and planting dates, as well as to estimate the genetic diversity and heritability of traits, an experiment was carried out for two years at the Agricultural Research Center of Kerman Province. The experiment was a factorial based on randomized complete blocks design with three replications. Five planting dates and six garlic ecotypes included experiment factors. Traits of flowering percentage, number of coating layers, number of cloves, clove weight, onion weight, onion diameter; dry matter content and yield were measured during growth season. Analysis of variance and mean comparison carried out with using SAS software. Correlation matrix and cluster analysis based on Ward’s method conducted with use of SPSS software. Finally, for the ranking of ecotypes based on all traits, use of Arunachalam and Bandyopadhyay (1984) method.

The results of compound analysis indicated that different planting dates differed in terms of most of the traits, in terms of dry matter and number of coating layers, and it was also determined that the effect of ecotype on all traits was significant, so that Ecotypes of Mazandaran and Guilan had the highest yield. Sandhu et al. (2015) reported a significant difference between ecotypes in terms of all traits. It was also found that the percentage of flowering, number of clove, clove weight, onion weight and yield were affected by the interaction of planting date in ecotype so that the highest yield was related to Jiroft and Shahdad ecotypes in the planting date of September 15. Among the ecotypes studied in this experiment, Gilan and Mazandaran ecotypes had flowering and flowering in other ecotypes was zero. Flowering is a genetic trait and this trait varies among ecotypes. The desirable characteristics of ecotypes related to the south of the country were non-flowering, which shows the superiority of these ecotypes to the ecotypes of Gilan and Mazandaran, although the ecotypes of Gilan and Mazandaran were superior in terms of yield. High broadscence heritability, high genetic and phenotypic coefficients of variation for flowering percentage, number of cloves, clove weight and onion weight were observed, indicating that these traits are more influenced by genetics and the probability of observing traits is higher in the next generation with the same quality. The cluster analysis divided the ecotypes into three groups. This indicates the genetic similartiy of each group ecotype.

Finally, the ranking based on Arunachalam and Bandiopadia (1984) showed that the most suitable ecotype among the studied ecotypes is the Jiroft ecotype so that there is no delay in its cultivation.