Evaluation of Amino Acid Biofertilizers for Stress Tolerance on Poa annua

Dr. Thomas Watschke & Jeffrey Borger (Penn State University)

Drought Evaluations
The effect of amino acid biofertilizers on drought tolerance was evaluated by withholding irrigation and monitoring wilting of the turfgrass.  Irrigation was resumed before the turfgrass was completely dormant and its rate of recovery was also monitored.

Results & Conclusions:
Turfgrass treated with amino acid based biofertilizers took longer to wilt (Fig. 1) and recovered quicker from wilting than did non-treated turf (Fig. 2).

Accumulation of organic compounds such as amino acids (especially proline) is a natural response of plants to drought stress and other adverse conditions.  Exogenous applications of amino acids increase the concentration of solutes within the cell, make the water potential in cells more negative, and increase the tolerance of turf to water stress. 

Heat Evaluations
On March 17, 1997, the Poa annua was placed into a growth chamber where temperatures were maintained at 95° F for sixteen hours during light time and 75° F during dark.  Turfgrass quality of Poa annua grown under heat stress was rated on March 25 and March 26.  On March 27, the turfgrass was placed back into the greenhouse and evaluated for rate of recovery.

Results & Conclusions:
Turfgrass under heat stress treated with amino acid biofertilizers had better quality than the control when first observed on March 25.  Treated turf also maintained a better quality than the control when evaluated March 26, especially the one treated with QUELANT™-Ca.  However, acceptable quality using this rating scale must be at least a seven.  Although no significant differences were observed on the turf recovering from the heat stress, the turfgrass treated with amino acid biofertilizers maintained a better quality on March 27.  QUELANT™-Ca appeared to enhance recovery rate of turfgrass when observed on April 3 and April 9.

Other Evaluations
Turf color was not significantly affected by any of the treatments when turf was not under adverse conditions.  Overall the turf color was good.  Weekly evaluations of turf height and clippings fresh weights done when the turf was not under stress indicated that MACRO-SORB® radicular or MACRO-SORB® foliar does not increase topical growth of Poa annua.  Similar trend was also observed when clippings dry weights were measured on March 3 and April 9.   Dr. R. Schmidt at Virginia Tech has obtained similar results on creeping bentgrass and he has suggested that amino acids biofertilizers may have some plant growth regulator effect on turfgrass.

Reference
Wallsgrove, R. M. (ed.). 1995.  Amino Acids and their Derivatives in Higher Plants.  Society for Experimental Biology Seminar Series 56.  Cambridge University Press, Cambridge.