عنوان مقاله [English]
Canola (Brassica napus L.) is one of the most important oil crops in the world. It has placed in third rank after Soybean and Palm and it has had the fastest of growth rate among oil seed in recent decades too. Canola yield was 1592 and 1567 kg.ha-1 in Iran and the world in 2003 respectively. It has increased 2125 and 2043 kg.ha-1 in Iran and the world in 2014 respectively. Crop physiologist should investigate the important physiological parameters which in the past have increased yield and can help to increase the quality and quantity of crop yield in the future. Therefore, the current study was carried out to evaluate the physiological traits associated with canola (Brassica napus L.) genotypes yield improvement.
Materials and Methods
Experiment was conducted as randomized complete block design with four replications at Higher Education Complex of Shirvan during growing seasons 2014-2015 and 2015-2016. Treatments were included 20 varieties and lines of rapeseed. The record of phonological stages was done based on Sylvester-Bradley (1984)’s method. Before the plants showed elongation, aboveground biomass and LAI were measured from destructive sampling and it has been continuing at intervals of 6 to 10 d until physiological maturity. Yield and components were measured at the end of the growing season. In order to investigation of growth indices, we have divided the varieties to three group based on cluster analysis and is select a variety as group representative. The groups are include high yield (Bilbao), medium yield (Karaje 3) and low yield (Sarigol).
Results and Discussion
Results indicated that there was significant differences among studied varieties in terms of phonological traits. So that Sarigol, Talatee, Shirali, Zafar and Zarfam were achieved earlier than others to physiological maturity. Positive and significant correlation of flowering duration with yield (r=0.66**) and the number of pod.plant-1 (r=0.88**) has showed its importance in determination of yield. Also, the most important of stage at making yield affected by environmental conditions such as temperature, radiation and rainfall. LAI for Bilbao was higher than Sarigol and Karaje 3. Also, Sarigol was achieved maximum LAI earlier than two other varieties. There was strong correlation between yield and maximum dry matter accumulation (r=0.81**). The synchronization of maximum LAI with more solar radiation was much more important to achieve maximum yield. In the first year of experiment CGR and RGR were higher than second. There were more solar radiation in first year that it was increased growth indices, also, harvest index. The number of pod.plant-1, seed.pod-1, harvest index, biological yield and seed yield were higher in the first year of experiment. The part of difference of yield between two years associated with reduced growth indices and another reason was decreased harvest index. Generally, biological yield, harvest index, days to achieve maximum leaf area index and number of pods per plant displayed 99% of the total yield- related changes.