International Journal of Agriculture Extension and Social Development

author(s)
Noor Muhammad and Shah Alam Khan

abstract
The study is designed to investigate whether chlorophyll meter content readings (SPAD) can be used as to determine the tolerance in canola cultivars against arthropods. 10 canola cultivars were tested for chlorophyll limits (SPAD readings) in un-infested & infested plants at four to six leaves stage, flowering stage and pod stage at 15 days interval of aphid infestation. Feeding by mustard aphid L. erysimi K caused significant loss of chlorophyll in the infested plants of leaves un-infested plants have significantly higher chlorophyll than infested plant. The results showed that among various cultivars of canola differed significantly amongst the un-infested & infested plants of different canola cultivars there is significant difference in chlorophyll content. The results was multiplication of aphids/plant infestation (70.83) revealed that aphid density was significantly higher on Abaseen (367.75 aphid/plant) and lower on KS-75 (162.00 aphid/plant). In control, (un-infested plant) KS-75 was significantly higher (44.00 chlorophyll content/leaf) and Oscar lower (41.00 chlorophyll content/leaf). Among the artificially aphid infested plants, KS-75 (23.75 chlorophyll content/leaf) followed by Oscar (21.00 chlorophyll content/leaf) significantly higher while Abaseen (12.25) followed by Zahoor (12.75) lower. The chlorophyll content losses were significantly higher in Omega (30.75) followed by Shiralee (30.25) and lower in KS-75 (20.25) followed by (20.75) in Oscar. In term of infestation cause significantly low in KS-75 (46.02%) followed by Oscar (49.70%) while high in Omega (71.10%) followed by Abaseen (70.83%) respectively. The chlorophyll meter readings a positive correlation between and (%) infestation was over time strengthening and culminated at the physiological harvesting stage. It was a clear indication that the potential of the chlorophyll meter readings has to be used for the selection of susceptible/tolerant cultivars and may permit modern canola crop in the climate change scenarios to be grown at wider range of environments.