Evaluation location: Wisconsin, United States
METHOD: Chemical Assay CONDITIONS: Green House and Field METHOD NARR: Plants were watered with either of 2 nutrient solutions. The control watering solution was 1/4 strength Hoagland's solution. The treatment solution was maderol solution to 800 ppm calcium with calcium nitrate. Tuber tissue was processed and assayed for overall ppm calcium on a dry weight basis on whole tubers by atomic absorption spectrophotometry. Outstanding populations were93 random seedlings were chosen from populations of the three outstanding selections. In 1994 these selections were grown in the field and tuber tissue was analzed. In 1995 progeny were obtained by crossing selected genotypesthen compared to a random sample of individuals from the original populations. RESULTS NARR: Since tuber peel contains much more calcium than the flesh, observed calcium levels of entire tubers should be adjusted so that species proll tubers can be more accurately compared. If this is done, ktz selections are no longer significantly higher than cultivars, but mcd selections still are. The 1995 tests show that populations can be changed by recurrent Continued fine screening and recurrent selection may be able to produce populations uniformly extreme (homozygous) for as many as possible of the gnes that contribute to extreme tuber calcium.