TITLE:
Bioassay of Winter Wheat for Gibberellic Acid Sensitivity
AUTHORS:
Alexander D. Pavlista, Dipak K. Santra, David D. Baltensperger
KEYWORDS:
Plant Growth Regulator; Gibberellin; Planting Aid; Cover Crop
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.10,
October
17,
2013
ABSTRACT: Increasing
winter wheat seedling growth would make it a better winter cover crop.
Gibberellic acid (GA3) seed treatment may accomplish this
by stimulating stem growth. A bioassay, mimicking field conditions, could
determine the relative sensitivity of conventional and semi-dwarf cultivars. In
growth chambers set for cool (10℃/4℃) and warm (21℃/4℃) conditions, wheat
seeds were treated with 0 and 125 to 16,000 ppm GA3. The
cultivars Goodstreak (tall or conventional) and Wesley (semi-dwarf) were
compared as standards. Emergence and plant height were measured. “Goodstreak” showed a significant
growth promotion at 500 ppm GA3 when seeds were dipped and 2000 ppm
when GA3 was applied in-furrow under both temperature regimes. “Wesley” in general required the
same or a higher dose of GA3. Separately, the seeds of nine other cultivars
were treated with GA3 as the standards. Based on maximum height promotion,
the most sensitive cultivars under cool conditions were Goodstreak, Harry,
Millenium, and Wahoo; under warm conditions, the most sensitive cultivars were
Alliance, Goodstreak, Jagalene, and Millenium. In general, the least GA3 sensitive cultivars were Arrowsmith, Scout66, and Wesley. “Buckskin” and “InfinityCL” were intermediate. The
rye cultivar Rymin also was tested and showed less sensitivity to GA3 than “Goodstreak”. When 6 benzyladenine (6BA) with GA3 was
applied to “Goodstreak” and “Wesley” seed, emergence, plant
height and weight, and tiller formation were reduced. Wheat cultivars will
respond to GA3 and differ in the amount of GA3 needed.
The results of this growth chamber study will guide subsequent field trials.