Seedling development, and ethephon

Recent reports indicate that tall fescue (Festuca arundinacea Schreb.) may be selected for increased disease resistance with the use of a marker such as chitinase, a defense protein associated with disease resistance in tall fescue. The objective of this study was to determine if chitinase activity in tall fescue cultivars differs consistently across seedling stage, and to determine if chitinase activity could be increased with ethephon ([2-chlor oethyl]phosphonic acid), a growth regulator used as a chemical elicitor. Te n cultivars of tall fescue were planted in a greenhouse, and seedlings were harvested at 14, 28, and 42 d after germination. Seedlings were treated wi th and without ethephon 3 d prior to each harvest. Foliage was analyzed for total and specific chitinase activity. Both total and specific chitinase a ctivity differed (P < 0.01) among cultivars and seedling stages. Highest ra nking cultivars expressed at least 16% more total chitinase activity and 18 % more specific activity than the lowest ranking cultivars. Though chitinas e activity changed drastically over seedling development, there were no cul tivar X seedling stage interactions (P < 0.01) for total or specific activi ty. Ethephon increased total and specific activity only at the 0.06 and 0.0 7 probability level and was far less effective than biological elicitors us ed to increase chitinase in previous studies. We concluded that chitinase c ould serve as a consistent marker among tall fescue cultivars across seedli ng stages, but a more effective chemical elicitor would be desirable to inc rease chitinase activity.