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- Author or Editor: Ian Warrington x
Abstract
Clonally produced plants of Cymbidium Astronaut ‘Rajah’ (3.5 years exflask) were assigned to three day/night temperature regimes (20°C day/12° night, 26°/12°, and 26°/18°) at two nitrogen fertilizer rates (17 and 170 ppm N in the daily nutrient feed) in controlled environment rooms in Oct. 1984. Plants were removed at seven regular intervals between 29 Oct. 1984 and 15 Apr. 1985 and destructively harvested for assessment of bud development. There were, on average, 4.4 renewal vegetative buds (≥25 mm long) per plant produced over the 6-month experimental period with no apparent effect of temperature or nitrogen treatments on this cultivar. Of all vegetative renewal buds, 73% occurred on the bottom two nodes of the pseudobulb, whereas only 36% of reproductive buds grew from the bottom two nodes. Reproductive buds occurred up to the eighth node. By harvest 7, the 26°/12° temperature regime resulted in 5.9 reproductive buds per plant, with only 0.8 and 1.7 reproductive buds per plant, respectively, observed for the 20°/12° and 26°/18° temperature treatments. There was no effect of nitrogen fertilizer on floral bud numbers.
The characteristics of 1-year-old vegetative spurs growing on 2-year-old branches were measured on 28 `Delicious' apple (Malus domestica Borkh.) strains growing on M.7 rootstocks at Clarksville, Mich., and on 23 strains of `Delicious' on M.7a rootstocks at Kearneysville, W.Va. Spur-type strains typically had densities >20 to 21 spurs/m, and high spur leaf numbers, leaf areas per spur, leaf areas per leaf, and terminal bud diameters, whereas values for standard strains were generally lower. However, for most spur quality characteristics, there was a continuous range of values between the extremes rather than any distinct grouping into either spur or standard type. At both sites, spur density was significantly and positively correlated with yield efficiency. In a related study, the spur characteristics of `Starkspur Supreme' were measured on nine rootstocks: M.7 EMLA, M.9 EMLA, M.26 EMLA, M.27 EMLA, M.9, MAC 9, MAC 24, OAR 1, and Ottawa 3. Spur leaf number and spur leaf area were both high with vigorous rootstocks, whereas spur density was low. The rootstocks MAC 9, M.9, and M.9 EMLA had the highest yield efficiencies.