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- Author or Editor: D. Cosgrove x
The effect of 3 growth regulators on the growth and flowering of Gerber jamesonii Hook. f. were evaluated. Two applications of daminozide and ancymidol restricted the height of gerbera, but no response occurred with chlormequat. Ancymidol was more effective than daminozide, especially when applied 6 or 7 weeks after transplanting. Times to visible bud and leaf number were not affected by growth regulator treatments. Plants were more responsive to daminozide when applied 8 weeks after transplanting compared with 5, 6, or 7 weeks.
A shift in the form of Ν in the nutrient solution to all NH4 after initial bloom significantly reduced pod yield as much as 50%, depending on the prebloom NO3/NH4 ratio. Pod yield was unaffected by prebloom NO3/NH4 ratio if at least half of the Ν in the nutrient solution was NO3, or if NO3 supplied all of the Ν during postbloom development. Therefore, for maximum pod yield, NO3 should be the primary Ν form supplied to snapbean plants after bloom. Kjeldahl Ν values were consistently high in the vegetative tissue with NH4 as the predominant Ν form, indicating that the use of Kjeldahl Ν values as an indicator of the Ν status of the plant in relationship to pod yield would be a misuse of this diagnostic tool without knowing the predominant Ν form being absorbed by the plant. The NO3 content in upper mature leaves at pod maturity was significantly correlated (r = 0.88***) to NO3 level applied, with a value of 7000 ppm in the leaves associated with highest pod yield. Total Ν (Kjeldahl Ν + NO3) of at least 5.50% in upper mature leaves at pod maturity was associated with highest pod yield.