EVALUATION OF TUBER BEARING SOLANUM SPECIES BELONGING TO DIFFERENT PLOIDY LEVELS FOR ITS YIELDING POTENTIAL AT LOW SOIL FERTILITY

Virus free tubers from thirty-six clones of tuber bearing Solanum species belonging to different ploidy levels, from the world gene bank at the International Potato Center, were cultivated under field conditions at low and high fertilizer rates. Nine of the clones were chosen for their high yielding potential (advanced group) and twenty-seven for their extensiveness (native group). The tuber yields of the thirty-six clones at the two fertilizer levels were positively correlated and the advanced group yielded more than the native group, even under conditions of low soil fertility. A broad genetic variation in root size at both fertilizer levels was apparent. Although some native clones showed rather large root systems as a group, the advanced clones had a similar root dry weight to the native clones. Tuber dry weight was significantly correlated with root dry weight but the advanced clones had a higher tuber yield per unit of root dry matter produced.