Evaluation of The Effect of Plant Growth Retardants on Vegetative Growth, Yield Components, Seed Quality And Crop Maturity of The Kabuli Chickpea Cultivar CDC Frontier
Chickpea production in the short growing season of the Canadian Prairies is still a challenging task due to excessive and continuous vegetative growth which often results in severe yield and quality reduction. This study examined the effects of three plant growth retardants (PGR), Chlormequat Chloride (CCC), Prohexadione Calcium and Trinexapac Ethyl applied during flowering stage on vegetative growth, seed quality, yield and crop maturity of the Kabuli chickpea cultivar CDC Frontier. Field experiments were conducted at Brooks and Bow Island in southern Alberta in the 2010 and 2011 growing seasons. Four concentrations of each PGR were applied at 10, 20 and 30 days after flowering (DAF) stages. During the 2010 growing season the crop experienced above average moist and cooler temperature conditions. In contrast, later half of the 2011 growing season was above average dry and hot. None of the three PGR tested in this study had a significant effect on plant height at 30 days after treatments or on above ground biomass plant-1 at harvest. Application of PGR had no significant effects on the number of seeds m-2, except at the Brooks rain-fed site in 2011 where the PGR treatment applied at 10 and 20 DAF increased the number of seeds m-2 at harvest. An increase of 1000-seed weight of marketable seeds was obtained with Prohexadione Calcium and Trinexapac Ethyl applications at Bow Island, but the effects were not consistent across sites and years. Results suggested that the effect of PGR on 1000-seed weight of marketable seeds mainly depended upon the growing environment and the type of PGR. In general, PGR applications reduced the total and marketable seed yields. Application of Prohexadione Calcium and Trinexapac Ethyl at the Bow Island site delayed crop maturity in 2011. In contrast, the application of CCC at 6000 mg L-1 at 20 DAF accelerated crop maturity at the Brooks irrigated site in 2011. In addition to this main study, the potential effects of Pyraclostrobin and Prothioconazole fungicides on the activities of the three PGR were compared by a separate experiment conducted at the Brooks irrigated site in 2011. The results of that study revealed that there were no significant differences in the effects of PGR on chickpea vegetative growth, seed yield parameters and maturity when they were applied as a mixture with either Pyraclostrobin or Prothioconazole fungicide. In summary, results revealed that PGR applied during flowering stage were not effective on controlling vegetative growth of chickpea and did not improve seed yield and crop maturity. Their effects on yield-related traits were highly inconsistent. Thus, it can be concluded that the application of PGR is not a reliable agronomic option to handle the production issues associated with continues vegetative growth at the late reproductive stage of the chickpea cultivar CDC Frontier under the western Canadian growing conditions.
Chickpea, Maturity, Seed Quality, Plant Growth Retardants, Indeterminate Growth
Master of Science (M.Sc.)