Studies on Poteto Breeding by Polyploid Hybrids between Related Species (1) : The Leaf Smear Method in Identifying polyploid Plants

The detection of chromosome doubled plant in polyploid breeding has been made by the shape and thickness of the leaf, the size and number of stomata, the size of pollen etc. But there is a wide variation in these characteristics especially in the size of stomata sometimes leads into incorrect conclusions. Accuracy may be attained if the number of chromosomes be counted, but the general methods which have been adopted were conditioned by the time of sampling and are apt to injure plants. Particularly, most of these methods are not applicable to these breeding techniques which necessitate an early identification prior to the full maturity of plants. The authors are now working on a method in which the young leaf is taken as a test material, so that we may identify the doubled plants earlier, and yet may not injure plants in breeding by species hybridization. The recent experiment worked out a method suitable to genus Solanum by adding a little modification to the Leaf Smear Method (PRAKKEN and SWAMINATHAN 1950,1951) which was founded on TJIO's study (TJIO and LEVAM 1950,GERSTEL 1949).