Relationship of foliar injury, plant height and vine maturity to yield of potato clones following metribuzin application

Abstract

Relationships between potato tuber yield and other plant characteristics including foliar injury, plant height and vine maturity, were measured following metribuzin (4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one) application in 1986 and 1987. Metribuzin was applied postemergence when plants were 20 cm tall. Measurements for foliar injury were taken one, two and three weeks following application, vine height 60–70 days after planting, and vine maturity 90–100 days after planting. Correlations with relative yield (treated/control) were computed for foliar injury at the three dates, relative plant height (treated/control), and relative vine maturity (treated/control) rating. Foliar injury one week after application was moderately well correlated with relative yield with r values ranging from −0.48 to −0.86 (p < .05) depending on the experiment. As time between application and injury evaluation increased, the correlation strengthened. After 3 weeks the correlation coefficients ranged from −0.64 to −0.92 (p < .01). Relative plant height was highly correlated with relative yield with correlation coefficients ranging from 0.80 to 0.85 (p < .001). Relative vine maturity rating showed a low and erratic correlation with relative yield. Foliar injury measured three weeks after metribuzin application and plant height reduction appear to be easily measurable indicators of yield response.