--V. K. Chaudhary and J. L. Minocha

While using various chemical mutagens (EMS, EB and SM), albino seedlings were observed in M1 generation. The frequency of such seedlings varied in different treatments (Table 1). Besides, streptomycin treatment (SM) also produced 5 and 23 such seedlings with their central leaves white out of which 3 and 19 seedlings respectively could not survive. The rest could recover and develop like a normal plant and did not give any chlorophyll deficiency symptoms in subsequent generations. This appearance of albino mutants was also observed in M2 and M3 generations in the progeny lines that gave albino mutants in M1 generation. The frequency of such seedlings was different in different treatments and crop seasons (Table 1). It is apparent that among all the treatments streptomycin produced the highest frequency of albino mutants in each generation, indicating its superiority over other mutagens used for creating such mutants. The frequency of these mutants was observed to be higher in winter (21±1 C) than in summer (30±1 C) (Table 1). This gives an indication that low atmospheric temperature may play some role in enhancing the expression of the albino phenotype in the presence of certain chemical mutagens used here that affect the chloroplast development or the factors in the chloroplast.

Table 1. Frequency of albino seedlings.
 

	Frequency of albino seedlings (%)
	M1		M2			M3
Treatment	Sum.	Sum.	Wint.	Sum.		Wint.
EMS 0.1% 24hr	0.8	12.5	15.7	11.9		13.8
EB 0.1% 48hr	0.4	- Not obtained -
EB 0.2% 48hr	1.5	10.2	10.9		9.9	11.2
EB 0.2% 48hr	0.5	19.4	21.2		12.5	13.2
SM 0.1% 48hr	3.0	38.0	39.0		15.7	17.2
SM 0.2% 48hr	4.6	40.0	41.0		16.5	17.1
EB 0.2% 48hr	1.1	19.5	21.0		11.2	13.4
SM 0.1% 48hr	1.3	20.3	23.9		15.8	18.6
Control H20	NIL	NIL	NIL		NIL	NIL

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