DIFFERENTIAL VARIETAL RESPONSE OF GREEN PEA (PISUM-SATIVUM) TO METRIBUZIN

Field and greenhouse experiments evaluated the differential response o f 15 green pea varieties to metribuzin applied preemergence. 'Charo,' 'CMG 298,' 'Leah,' 'Scout,' and 'Puget' were the most tolerant, wherea s 'Bolero' and 'Sundance' were the most susceptible varieties under gr eenhouse conditions. Variable chlorophyll fluorescence (F-v), efficien cy of photosystem II (F-v/F-max), and leaf area were reduced sharply b y metribuzin in susceptible varieties, and metribuzin susceptibility c orrelated highly with the reduction in shoot dry weight. Green pea var ieties grown under field conditions responded to metribuzin similarly to pea varieties grown under greenhouse conditions. Metribuzin reduced shoot dry weight more in peas grown at 30/25 C than in those grown at 25/20 and 20/15 C. Also, metribuzin injured peas more when grown in s oil saturated to field capacity compared to soil at 70 and 40% of fiel d capacity.