Delay Cropping Effect on Yield, Yield Component and Grain Oil Content of Milk Thistle (Silybum marianum) under Subtropical Climatic Conditions of Southern Kerman

This research was conducted in order to investigate some quantitative and qualitative traits of milk thistle under the influence of delayed planting dates in 2016 at the research farm of University of Jiroft. The experiment was carried out in the form of split plots in the form of a randomized complete block design in three replications. The main factor in this experiment was six planting dates (November 10, December 10, January 10, Bahman 30, March 10, April 10) and the secondary factor was three ecotypes of thistle (Kashan, Sari, Malathani). The measured traits included number of Capitulum per plant, number of seed per Capitulum, Weight of 1000 Seeds, plant height, seed yield and grain oil content (%). The results showed that the effects of planting date, ecotype and their interaction on all studied traits were significant (P<0.01). Under the influence of the delay in planting, all studied traits decreased linearly and significantly (P<0.01, R2>0.85). Based on these results, the decreasing slope under the influence of delayed cultivation was different in the examined ecotypes, so that the highest and lowest absolute values of the decreasing slope were observed in Malathani and Kashan ecotypes, respectively. The results illustrated that for every 10 days of delay in planting, seed yield decreased in Malathani, Sari and Kashan ecotypes by 251.4, 239.1 and 134.6 kg per hectare, respectively. The oil percentage decreased by 0.62 and 0.31, and 0.58 percent respectively. In general, in the subtropical conditions of Jiroft, the optimal planting date is November. The comparison between ecotypes also showed that although Mulathani and Sari demonstrated the highest yield of seeds and oil on the first planting date, Sari ecotype had more yield stability during the different planting dates.