Under genotypes were culture in MS medium supplemented

Under this study significant differences (p <0.01) were observed among the genotypes for PCI, RFWG, RGR, CGR, CFW, CDW and RWC respectively indicating the presence of genetic variability, different responses of genotypes to callus induction and  possible in vitro selection of callus induction from internodal segments of potato. Same callus characteristics were evaluated and found significant difference in maize (El-Aref, 2002) and bread wheat (Elyasi et al., 2012; Farshadfar et al., 2012). Callus cultures are used as an in vitro technique for biochemical and physiological studies in response to stress at the cellular level (Liu et al., 2006). Reliable callus induction and regeneration of viable plants considered as limiting steps to the successful use of modern techniques in genetic improvement of the major crops are reported by Murphy (2003). Moreover, many researchers reported that 2,4-D as the best auxin for callus induction in monocot and even in dicot (Mamun et al., 1996; Bordallo et al., 2004; Elaleem et al., 2009; Dhaka and Nailwal, 2015). The auxin 2,4-D by itself or in combination with cytokinins, has been widely used to enhance callus induction and maintenance. In this experiment internode derived callus was observed within 8-22 days and the percentage was varied from 56.67 - 100% and showed greenish white color with friable texture. In this case almost all studies genotypes were culture in MS medium supplemented with 3 mg/L 2,4-D with 0.5 mg/L Kin. This result is in agreement with Elaleem et al., (2009) who observed 100% friable green callus was initiated when 2,4-D (2.0 mg/L) was used in combination with BAP at the same concentration. It was observed that when 2,4-D used in combination with Kin that produced friable greenish calli within shortening time (Table 1). Analysis of variance for different morphological characters viz. PCI, RFWG, CGR, RGR, CFW, CDW and RWC indicated highly significant difference (p <0.01) among the genotypes for all physical characters (Table 2). Mean comparison of the traits measured in callus induction and found that Sheelbilati and Surjamukhi had the highest PCI (100%). The highest amount of CGR (0.66), CFW (0.28) and RWC (91.58) recorded for Surjamukhi and RFWG (9.70), RGR (0.11) recorded to Jamalu and finally CDW (0.04) belongs to Patnai. While the lowest amount of RFWG (1.66) and RGR (0.05) was attributed to Asterix. The CGR (0.16) and CFW (0.12) were recorded for Chollish. The lowest PCI (56.67) and CDW (0.02) were observed in Ausha and RWC (75.35) was in Dohazari. The results of callus induction traits (Fig. 1, Table 3) obviously revealed that culture response was greatly influenced by the potato genotypes and also emphasized a profound effect of genotypes on callus induction and regeneration which agreed well with the findings of Forooghian and Esfarayeni (2013) and cereal crops e.g. durum wheat (Ozgen et al., 1996; Bommineni & Jauhar, 1996) and bread wheat (Elyasi et al., 2012). The importance of genotype in determining the in vitro response of potato tissues has been recognized and the efficiency of callus induction, callus growth rate and plant regeneration frequency have been reported to other crops and maximum cases it was dependent by genotypes (Khatun et al., 2003; Haque et al., 2009; Yasmin et al., 2011). They found significant difference between and among different crop cultivars for callus induction. They also reported that the callus induction depends on genotypes (Birsin & Ozgen, 2004; Shah et al., 2009). In general, callus induction used as an efficient character for assessment of culture responses from internodal segments in different Bangladeshi potato genotypes. The callus fresh weight is provided a more concise quantitative character for the development rate of callus.