Seed characteristics and nutrient composition of selected beans (Phaseolus vulgaris L.) with different ozone tolerance.

Ozone sensitivity, nutritional quality, seed characteristics, and growth habit of beans (Phaseolus vulgaris L.) were evaluated in two separate experiments. In the first experiment the data showed a significant variation among 34 bean accessions for ozone sensitivity following acute exposure of 18-day-old plants to 0.6 microliters/l O3 for 2 hours under environmentally controlled greenhouse conditions. PI-163579, PI-169735, PI-171790, PI-176684, PI-201374, PI-310711, PI-345576, PI-370569, PI-379435, and PI-414831 were identified as tolerant to acute ozone exposures. Protein, oil, starch, sugar, and ash contents in the seed of selected germplasm were determined and no correlation was found between these components and ozone sensitivity. Seed size and growth habit varied considerably among the 34 accessions but were not correlated to ozone sensitivity. In a second experiment, ten accessions, selected from the tolerant ones identified in the first experiment, were subjected to chronic ozone exposure in open-top chambers at 0.04 and 0.08 microliters/l concentrations for 7 hours/day 44 days after transplanting. Based on foliar injury and yield reductions, only PI-370569 and PI-414831 were tolerant to prolonged ozone exposure (0.08 microliters/l). A significant positive correlation (r = 0.83) existed between foliar injury rating from chronic treatments involving 0.04 and 0.08 microliters O3/l and acute exposure (0.6 microliter O3/l/2 hours). The data indicated that acute ozone exposure can be used to initially screen a large number of bean accessions, however, this is an imperfect indicator of ozone sensitivity with chronic exposure.