Investigation the effect of plant density on phenological stages, morphological traits, yield and yield components of different cultivars of Rapeseed

Increasing the world's population and improving living standards is one of the reasons for increasing the production of oily crops for arable consumption. In this regard, rapeseed is superior to other oilseed crops in the country due to its positive traits such as resistant to cold weather and drought stress, salt tolerance and higher yield per unit area. The factors affecting the yield of plants are the use of suitable cultivars adapted to the climatic conditions of each area in appropriate planting density, in such a way that there is at least a destructive competition between the plants. Regarding the fact that each plant, or, in a better way, indicates a specific reaction to environmental factors, and also due to the high capacity of rapeseed for improving the yield as a result of environmental factors, this study aimed to determine the most suitable plant density and variety for improving yield and yield components of rapeseed.

In order to investigate the effect of different densities on yield and yield components of different rapeseed varieties, a factorial experiment was conducted in a randomized complete block design in a research farm of Gharakhil Agricultural Research Center in Ghaemshahr in 2017-2018, The treatments consisted of five intervals on rows of 3, 3.5, 4.5, 6 and 9.5 cm, respectively, with densities of 66.67, 57.14, 44.44, 33.33 and 21.05 plant, respectively. Second factor for this experiment was included four canola cultivars: Hayola 401, Agamaks, Hayola 4815 and Terrap, which were performed in three replications.

The results showed that the highest biological yield and seed yield (11150 and 2942 kg ha-1) were related to Hyola 401 cultivar with 44.44 plant m-2. The main effect of density and variety on harvest index, 1000 seed weight, number of pods, number of seeds per pod and number of branches were significant. The density of 44.44 plants per square meter was the highest in pod (21.58), 1000 grain weight (4.24 gr) and harvest index (59.16 percent). The results also showed that the highest number of branches and pods per plant was related to density with density 33.33 plant / m2. In all studied traits in this study, except for the number of branches, the Hyola 401 cultivar showed better performance than other cultivars.

The results showed that there is a significant difference between plant densities and different cultivars for all measured traits. The results of this study showed that Hyola 401 cultivar with 44.44 plants m-2 had the best result in terms of biological yield and grain yield. Therefore, according to the results, Hyola 401 cultivar and 44.44 plants m-2are recommended for achieving high yield in rapeseed.