MSc

The effect of gamma rays and 'EMS on ten Cucumis melo L. varieties was studied in the M1 generation.
Germinability of seeds was not significantly affected by the different mutagen doses. However in general germination percentage decreased in varieties Panavalli, Attenganam local, Lucknow Sweet, Verma Surprise and Punthala local with gamma ray treatment while in Mudikode local, Pulliporan, Vellanad local and Co-1 germinability was better. EMS treatments in Mudikode local, Hara Madhu, Pulliporan, Puthala local and Co-1 resulted in decreased germination percentage.
Significant delay in completion of germination compared to control was observed in different levels of gamma ray treatments in some of the varieties while early germination was noted in some others.
Survival percentage, in general, was reduced with mutagen treatment in most of the varieties.
Chlorophyll chimeras were noticed in both mutagen treatments. Morphological variations observed included leaf and fruit abnormalities.
In general the lower doses of gamma rays resulted in early flowering of male flowers while 30 kR treatment resulted in delayed male flowering. Among EMS treatments, 1.0% and 2.0% treatments in general resulted in a delayed production of first male flower.
In the case of appearance of first female flower a significant delay was observed in the higher doses of gamma ray treatments in Co-1 and Attenganam local while a significantly early appearance of first female flower was noted with lower doses of gamma ray treatments in Mudikode local, Lucknow Sweet and Pulliporan. The 1.5 % and 2.0% EMS treatments in general produced first female flower earlier than control and 1.0% treatment.
In most of the varieties the EMS treatments in general resulted in the apperance of the first male flower at lower nodes compared to control. EMS treatment induced appearance of first female flower at lower nodes than gamma ray treatment.
Increase in sex ratio (male to female) due to some of the EMS treatments was observed in some varieties while a decrease was observed in others. Irradiation with higher doses of gamma rays caused decreased sex ratio in Panavalli, Lucknow Sweet, Hara Madhu, Pulliporan and Punthala local.
In general in all varieties there was reduction in pollen and seed fertility with increase in dose of gamma rays and EMS except 10 kR gamma ray treatment and 1.5% EMS treatment where a slight increase in seed fertility was noticed.
Different varieties showed differential response to different levels of gamma rays and EMS for number of fruits produced per plant and also for lenght and girth of fruit. Higher doses of gamma rays in Mudikode local, Co-1 and Pulliporan recorded greater fruit weight compared to control while 30 kR treatment in Panavalli and Punthala local recorded lower fruit weight compared to control. In Mudikode local, Panavalli, Vellanad local and Co-1 irradiation of gamma ray in general resulted in significantly lower yields than their control while in Attenganam local gamma ray irradiation resulted in significantly increased yield compared to control.
Significantly lower fruit set compared to control occured in 20 kR treatment in Panavalli, Punthala local, Pulliporan and Co-1 whereas 10 kR treatment in Lucknow Sweet and Vellanad local resulted in a significant increase in fruit set. Lower levels of EMS treatments in Hara Madhu, Co-1, Pulliporan and Panavalli induced significantly lower fruit set compared to control.
Irradiation with gamma rays resulted in significantly lower number of seeds compared to control in Mudikode local and Punthala local while in Pulliporan greater number of seeds than control was produced due to gamma ray treatment.
In Co-1 and Attenganam local, 2.0% EMS treatment resulted in a significant reduction in 100 seed weight while lower levels of EMS treatments in Lucknow Sweet resulted in a significant increase in 100 seed weight compared to their control.
The 10 kR treatment of all varieties in general resulted in slight decrease in mean length of main vine compared to control whereas the higher levels of gamma rays resulted in slight increase in mean length of main vine. In general the 2.0% EMS treatment of most of the varieties induced slight reduction in mean length of main vine while the lower levels of EMS resulted in slight increase in mean length of main vine compared to control.