Effect of photoperiod on microtuber production 
MS medium supplemented with 4 mg/L KIN 
showed best response in tuberization. Hence, only 
this treatment was used to study the effect of 
photoperiod on microtuber production. The results 
were presented in Table 2. In vitrotuberization 
potentiality of Diamant variety was influenced by 
photoperiod. Tuber formation period of the culture 
was the lowest (21.93 days) under dark condition 
and it was the highest (35.07 days) in light 
condition. Number of tuber per explant (1.93) and 
average weight (305 mg) of microtuber were also 
higher in dark condition than light condition. Under 
light condition most of the culture produced green 
microtuber. It might be due to synthesis of the 
alkaloid solanin. It was also interesting to note that, 
green micro tuber produced sprouts (Fig 2 &3). 
Similar phenomenon was reported by Wany and 
Hu (1982). On the other hand, brown coloured tuber was observed in dark condition and did not 
showed no sprout initiation. The experimental 
finding reveal that, dark condition is favorable for 
tuberization. Mares et al. (1981) observed that 
microtuberization at 16 or 24 hours photperiod was 
better than 8 hours. Wattimena (1983) indicated 
that the longer the photoperiod, better was the 
tuberization.