%0 Journal Article %T Evaluation of Quantitative Traits of Bread Wheat (Triticum aestivum L.) Cultivars in Different Planting Dates %J Journal Of Agroecology %I Ferdowsi University of Mashhad %Z 2008-7713 %A Garshasbi, leila %A Paknejad, Farzad %A jasemi, seyed shahryar %A Ilkaee, Mohammad Nabi %A sanjani, sara %D 2020 %\ 12/21/2020 %V 12 %N 4 %P 703-721 %! Evaluation of Quantitative Traits of Bread Wheat (Triticum aestivum L.) Cultivars in Different Planting Dates %K Biological yield %K grain yield %K Phenological stage %K Yield components %R 10.22067/agry.2021.37597 %X Introduction Besides its commercial importance in the global wheat market, bread wheat (Triticum aestivum) is an efficient weapon in political and international relations. Its practical importance is increasing by the day. The planting date is an essential factor in crop production because meteorological parameters vary with the planting date changes. Singly or in combination, temperature, sunlight, and other meteorological factors influence plant growth and production. Planting date controls plant phenological total biomass production and influences the efficient conversion of biomass into economic yield (Khichar and Niwas, 2006). The purpose of determining planting date is to find the right time for a cultivar or a group of similar plant cultivars so that the set of environmental factors are suitable for seed germination and seedling establishment survival (Hore et al., 2002). It seems that planting various wheat cultivars by considering the high importance of wheat with different growth habits is necessary for agricultural experts and farmers to observe the different cultivars' responses to various planting dates and weather conditions. Various cultivars, each compatible with weather conditions in a specific part of the country, were selected for this experiment. This experiment intended to determine how cultivars responded to each planting date by taking its yield potential and temperature changes into account, identifying the optimum planting date for each cultivar, and introducing the suitable cultivar in the late planting date.   Materials and Methods The split-plot experiment was conducted based on a complete randomized block design with three replications on the research farm of the Seed and Plant Improvement Research Institute in Karaj in two years (2015-2017). The bread wheat cultivars Baharan, Sivand, Sirvan, Mehregan, Chamran 2, Heidari, Zare, and Pishgam, formed the main plot factor and the various planting dates (12 October, 27 October, 11 November, and 26 November) the subplot factor. Yield and yield components such as the number of fertile spike per m2, number of grain per spike, number of grain per m2, 1000-kernel weight were measured at the end of the growing season to evaluate responses of the cultivars to the various planting dates. Also, the phenological stage was recorded during the growing season.   Results and Discussion Results indicated that planting dates had significant effects on grain yield, biological yield, number of seeds per spike, number of spikes per m2, and harvest index. The highest yield was 12 November among the planting dates, and the Sivand cultivar had the highest grain yield (7708 kg.ha-1). The interaction effects of planting date and cultivar were significant on grain yield, biological yield, and some yield components. The highest grain yield (9529 kg.ha-1) was observed in the Heidari cultivar planted on 12 October and the lowest (5474 kg.ha-1) in the Chamran cultivar planted on 26 November. Delays in planting reduced grain yield by 16-36% compared to the most suitable planting date (12 October) because of the reduced vegetative and grain-filling periods.   Conclusion The highest grain yield at each of the planting dates was achieved for one of the cultivars. Therefore, the cultivars adapted to different climates exhibited their highest yields at different planting dates. Based on results, it is recommended that the Heidari and/or Sirvan cultivars be planted in Karaj and regions with climates to Karaj on 12th October.  In cases of limitations concerning planting dates (unfavorable weather conditions, insufficient planting equipment, etc.), the recommended dates for planting the Mehregan and Sivand cultivars are from 27 October to 26 November to minimize yield loss caused. It seems that 12 October is the best planting time for the study region because it allows better use of the environmental conditions, including more desirable temperature, more extended growing season, higher soil moisture content, and suitable seedling establishment. %U https://agry.um.ac.ir/article_37597_fbb2b58e70ed0982ab8b25893d635c28.pdf