Abstract
Research was conducted to determine the effect of a Trichoderma-based plant stimulator (TBS) on papaya seedling growth. Papaya seedlings were grown from seed in 0.5-liter Styrofoam containers filled with a commercial substrate (30% sphagnum peat moss, 20% perlite, 50% vermiculite). TBS was applied as a drench at the rates of 0, 62.5, 125, 250, and 500 million conidia per seedling (MCS) at sowing, at seedling emergence, at 1 week after emergence (WAE), or 2 WAE. The variables evaluated were time from sowing to seedling emergence, shoot height, concentration of nitrogen in nitrate ([NNO[sub3]]) and potassium ([K[sup+]]) in leaf sap, leaf area, root dry weight, shoot dry weight, and time from emergence to readiness for transplanting. When TBS was applied 2 WAE, there were no significant effects on the variables evaluated. TBS applied at sowing did not significantly affect time to emergence. When applied at sowing, at emergence, and 1 WAE, all the other variables measured were affected to the same extent by a given TBS rate. At the rates of 250 to 500 MCS, [N-NO[sub3]] in leaf sap increased by 30%, [K[sup+]] in leaf sap increased by 22-25%, shoot dry weight increased by 28%, shoot height increased by 18%, root dry weight increased by 38%, leaf area increased by 22%, and time to readiness for transplanting was reduced by 10 days, as compared to control plants. These results indicate that TBS may be useful in increasing several growth attributes in papaya seedlings and in accelerating papaya transplant production.
