Effects of Four Growth Regulators on Photosynthate Partitioning in ‘Majestic’ Kentucky Bluegrass1
- K. V. Hanson and
- B. E. Branham2
Experiments were conducted in the greenhouse and growth chamber to determine the effect of plant growth retardants on photosynthate partitioning patterns in vegetative ‘Majestic’ Kentucky bluegrass (Poa pratensis L.). Single mature plants were treated with one of the following plant growth regulators (PGRs): Limit® (N- [(acetylamino)methyl]-2-chloro-N-(2,6-diethylphenyl)acetamide) at 2.84 kg ha−1, Cutless® (αa(1-methylethyl)-α-[4-(triflouromethoxy)phenyl]-5-pyrimidin meethanol) at 2.24 kg ha−1, paclobutrazol [(2RS,3RS)-l-(4-chiorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-oil at 2.24 kg ha−1, and mefluidide (N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide) at 0.28 kg−1. Partitioning patterns were examined 1, 2, and 4 weeks after PGR application by exposing individual leaves to 14CO2 and quantifying translocated 14C in immature leaves, mature leaves, crowns, axillary shoots (tillers plus rhizomes), and roots. In the greenhouse study, Limit tended to cause an increase in photosynthate accumulation in the crown with 63% of the applied label found in the crown at 4 weeks after application compared to 17% for the control plants. Mefluidide caused similar behavior with 39% of the label in the crown at week 4. In both studies, paclobutrazol caused a significant decline in photosynthate partitioning to the roots at week 4 with 20% vs. 49% for the control in the greenhouse study and 9% vs. 27% for the control in the growth chamber study. Cutless exhibited a similar response with 10% accumulation in the roots vs. 27% for the control at week 4. Mefluidide significantly increased translocation to the roots when compared to the control plant in the growth chamber study at weeks 2 and 4 (39% vs. 21% and 51% vs. 27%, respectively). Results of this study indicate that while all four growth regulators suppress top growth, each alters partitioning patterns differently among above and below ground organs, an important factor in understanding turf response to PGR application in the field.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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