Analysis of variance
M
2 and M
3 populations imparted significant differences for most of the traits studied.
Quantitative characters (Micro mutations) in M2 and M3 generations
EMS and Gamma radiations proved to be very effective to induce variability in quantitative traits in M
2 and M
3 generations (Table 1 and Table 2). Positive as well as negative impact on quantitative traits was well documented by
Barshile et al., (2008) in chickpea,
Bolbhat and Dhumal (2009),
Dhumal and Bolbhat (2012) and
Kanaka (2012) in horsegram.
Plant height
All the mutagens were effective for inducing variability in plant height in M
2 generation (Table 1). The DMRT represented the similar group (Group h) for minimum plant height in 200 Gy+0.3% EMS (71.47 cm), 200 Gy+0.5% EMS (70.93 cm) and 300 Gy + 0.2% EMS (60.97 cm) as compared to control (92.13 cm). Gamma treatment of 100 Gy 98.43 cm) falls under Group a showed significant increase in plant height while other treatments showed -ve influence.
Similar trend in plant height was observed in M
3 generation (Table 2). Maximum plant height 93.53 cm in M
3 was noted in 100 Gy gamma rays (Group a). The minimum plant height of 72.23 cmwas noted in 300 Gy+0.4% EMS (Group f) through DMRT. The average height of control plants was 90.33 cm. All the doses/conc.ofgamma irradiation, EMS and their combinations caused reduction in plant height with few exceptions.Similar results werereported by
Dalvi (1990). Gamma irradiation exhibited a stimulatory effect of significant increase in plantheight. Findings of
Yaqoob and Abdur (2001) in mungbean and
Barshile et al., (2008) in chickpea were in agreement with above results.
Number of primary branches per plant
Data obtained in M
2 generation on number of primary branches per plant (Table 1) indicated that the mean values of this parameter showed positive and negative influence. 100 Gy and 0.4 % EMS (Group a) showed increased number of primary branches per plant. Maximum number of primary branches per plant was recorded in 100 Gy (9.23) and 0.4% EMS (8.87) over control (8.80). In combination treatments there was no definite pattern. The maximum decrease (6.63) was noted in 200 Gy + 0.5% EMS (Group j) compared to control (8.80). The highest increase (9.63) was noted in 100 Gy+0.5% EMS. In nine treatments the primary branches per plant were increased over control. Similar trend was obtained in M
3 generation (Table 2). Six treatments showed increase in number of primary branches per plant as compared to control and M
2. DMRT revealed that maximum number of primary branches was recorded in 100 Gy+0.3% EMS (9.40) over control (8.93) and categorized as Group a. The treatment 200 Gy+0.5% EMS (Group j) recorded least number of primary branches as 7.10. Almost all the treatments of gamma irradiation and EMS showed positive as well as negative impact on primary branches per plant in horsegram.
Dalvi (1990) and
Singh et al., (2000) also noted similar trend with physical as well as chemical mutagen.
Number of days required for 50% flowering
The results of the gamma radiation in M
2 generation in different treatments indicated that there was significant change in the number of days required for 50% flowering while in EMS and combination treatments there was no definite pattern. In all the gamma treatments, days to 50% flowering were less than control except 400 Gy. The minimum numbers of days required for 50% flowering were 66.87 DAS in 200 Gy (Group c) as compared to control (72.77 DAS). In the combination treatments, days to 50% flowering were less than control in 300 Gy with different concentrations of EMS
viz., 0.2 and 0.3% and 400 Gy + 0.2% EMS. Similarpattern was noted for M
3 generation (Table 2). The minimum days required for 50% flowering were 68.03 DAS in 300 Gy (Group b), 69.23 DAS in 200 Gy (Group b), 69.03 in 300 Gy+0.2% EMS (Group b), 70.13 in 300 Gy+0.3% EMS (Group b). The number of days required for 50% flowering was not muchas compared to control except few treatments. However, gamma radiation and combination with EMS treatments caused early flowering.
Dalvi (1990) also noted similar results in horsegram with different mutagens. The results recorded by
Gaikawad et al., (2005), Rudraswami et al., (2006), Manjaya and Nandavar (2007) and
Ahire (2008) in different legumes were supportive to the present findings.
Number of days required for pod maturity
The data recorded in Table 1 revealed that GR had succeeded in reducing the number of days required for pod maturity as compared to control. The results of gamma irradiation were highly significant for reducing the number of days required for pod maturity. The minimum number of days (97.37 DAS) required for pod maturity was noted in 200 Gy (Group c). The data obtained for M
3 generation was on par with M
2 generation (Table 2) where the minimum days required for pod maturity were 99.03 DAS in 300 Gy. Gamma radiation (200 Gy) was successful to induce earlier pod maturity by about 3-4 days as compared to control.
Singh et al., (2000) reported contradictory findings with reference to this parameter.
Number of pods per plant
Gamma radiation and EMS single and combination had induced variability in number of pods per plant in M
2 generation. The data recorded in Table 1 revealed that the treatments had stimulatory as well as inhibitory effect. In M
2 generation maximum number of pods per plant (59.23) was noted in 100 Gy+0.2% EMS (Group a), 59.13 in 300 Gy+0.3% EMS (Group a), 58.97 in 400 Gy+0.2% EMS (Group a), 58.66 in 200 Gy+0.2% EMS (Group a), 57.93 in 100 Gy (Group a) and 57.90 in 100 Gy (Group a) than control (57.00). The minimum number of pods per plant (48.40) were recorded at 200 Gy+0.4% EMS (Group f), (48.50) at 400 Gy+0.5% EMS (Group f), (49.40) at 0.5% EMS (Group f) and (49) 200 Gy+0.5% EMS (Group f) as compared to control. However, all the combination treatments have caused reduction in number of pods per plant except 100 Gy + 0.2% EMS, 200 Gy+0.2% EMS, 300 Gy + 0.3% EMS and 400 Gy +0.2% EMS.
The trend in variation of pod number observed in M
3 generation was similar to that of M
2 generation. M
3 generation had shown slight increase in pod number as compared to M
2 generation (Table 2). Maximum pods were recorded in 300 Gy+0.4% EMS (59.67- Group a) and minimum pods was recorded in 200 Gy+0.4% EMS (48.57- Group i) and 300 Gy+0.2% EMS (48.43- Group i). There was increase as well as decrease in number of pods per plant with different doses/concentrations used. The results of
Dalvi (1990) for horsegram were in agreement with present study.
Gaikawad et al., (2005) in lentil noted similar results. However, decrease in pod number was also recorded by
Barshile et al., (2008) in chickpea.
Pod length
All the mutagenic treatments showed inhibitory effect on pod length except 300 Gy+0.2% EMS (5.67 cm- Group a) than control (5.2cm) in M
2 generation. The treatments of GR, EMS and their combinations in M
2 as well as in M
3 did not show any significant change in pod length (Table 1). The results reported by
Singh et al., (2000) in
Vigna and
Dalvi (1990) in horsegram were in conformity with present findings. M
3 generation had shown slight increase in pod length as compared to M
2 generation (Table 2). In M
3 all the mutagenic treatments showed inhibitory effect on pod length except 200 Gy+0.2% EMS (5.80 cm- Group a) than control (5.60 cm).
Number of seeds per pod
All the treatments showed decreased number of seeds per pod except (0.3% EMS (5.93- Group a), 100 Gy+ 0.2% EMS (5.90- Group a), 300 Gy + 0.3% EMS and 400 Gy+0.2% EMS (6.00- Group a) compared to control (5.90). Data on total number of seeds per pod (Table 1) in M
2 progeny showed non-significant changes as compared to control. M
3 generation showed similar trend (Table 2). The results recorded in table indicated that all the treatments of mutagens of GR, EMS and GR+EMS exerted inhibitory effects on number of seeds per pod except 300 Gy + 0.2% EMS. Decrease in number of seeds per pod was recorded by
Dalvi (1990),
Dubey (1990),
Gaikwad et al., (2005) and
Barshile and Apparao (2006).
1000 seed weight
Results recorded on 1000 seed weight (Table 1) indicated that Gamma ray treatment of 100 Gy had exercised +ve effect on this parameter and showed increased 1000 seed weight (36.33g-Group a) compared to control (30.70 g). The results of M
3 generation were on par with M
2 generation (Table 2). The results with GR, EMS and GR+ EMS showed negative as well as positive impact in horsegram. Similar observations were also made by
Singh et al., (2000) in urdbean,
Gaikawad et al., (2005) in lentil
Sagade (2008). Increase in 1000 seed weight was observed in 100Gy (34.53-Group a) and 400Gy+0.2% EMS (34.93- Group a) compared to control (32.23 g) in M
3 generation.
Seed yield per plant
Mean values for seed yield per plant decreased in all treatments as compared to control (Table 1). All the mutagenic treatments of gamma radiation showed -ve effect except 300 Gy + 0.2% EMS (33.63 g- Group a). EMS (0.3%) (Group- abcde) caused maximum increase (31.03 g), while all other treatments showed reduction in seed yield per plant over control. The combination treatment 300 Gy+0.2% EMS had induced maximum increase (33.63 g) over control (30.67 g). But all other treatments had caused reduction as compared to control except 200 Gy+0.2% EMS (31.27g). In M
3 generation seed yield per plant was increased in 300 Gy+0.2% EMS (33.90g- Group a) as compared to control (32.37 g). The results are in line with the findings of
Priyanka et al., (2019). All the mutagenic treatments except few treatments showed inhibitory effect on seed yield per plant.
Patil et al., (2004) in soybean,
Auti (2005) in mung bean,
Banu et al., (2005) in cowpea,
Barshile et al., (2008) in chickpea and
Senapati et al., 2008 in black gram also recorded adverse effect on seed yield per plant due to various types of mutagenic treatments.
Hakande (1992) reported wider variability in yield due to mutagenic treatments in winged bean which was attributed to pollen sterility and genetical as well as physiological alterations caused by mutagens.
Yield is an important trait, as it governs the economic benefit. Its expression is inherited by many genes, which control the production, transport and storage of assimilates. Previous studies indicated that both additive and non-additive genes contribute to yield. The variability in yield was induced by mutagenic treatments. In the present study increased seed yield was attributed to increase in number of pods per plant, length of pods and 1000 seed weight per plant.