diameter (KFD) to thin ‘Delicious’ that were previously treated with Promalin at 80% king bloom (KB) to improve fruit typiness (E. Wittenbach, unpublished data). This response was similar, but of a greater magnitude, to that obtained with late or high
Effects of BA, Promalin and Dikegulac-sodium on frond number and overall growth in Boston Fern (Nephrolepis exaltata L.) were studies. Four weeks after transplanting, fern liners were sprayed with aqueous solutions of BA, Promalin and dikegulac-sodium. Chemical concentrations of BA and promalin ranged from 0 to 150 mg. liter-1 at 50 mg. liter-1 increments. Chemical concentrations of dikegulac-sodium ranged for 0 to 750 mg.liter-1 at 250 mg.liter-1 increments. Chemical treatments were arranged in a randomized complete block design with 6 replications. BA and Promalin significantly increased the number of fronds, average frond length, leaf area and dry weight as the concentration of the chemicals increased. In contrast, dikegulac-sodium significantly suppressed the average frond length, leaf area and dry weight when compared to the control. Similarly to BA and Promalin, dikegulac-sodium increased the number of fronds as the concentration of the chemical increased.
Spraying 9-month-old UC157F1 asparagus plants (Asparagus officinalis L.) with aqueous solutions of GA4/7, BA, and promalin ranging from 0 to 200 ppm in 200-ppm increments and using the mother-stalk method showed that BA continued to produce the most marketable shoots and obtained a higher level of effectveness. GA4/7 showed significance on several days during the harvest period. On the final day, there was no significant difference found for either GA4/7 or promalin. BA produced marketable shoots earlier than promalin, but in the end, both these chemicals were equally effective. Early interaction with GA4/7 × BA resulted in delayed shoot emergence. Promalin is a mixture of GA4/7 and BA.
NAA and Accel are used for fruit thinning of apples. However, when combined, many small (<65 mm) fruit were produced in `Delicious'. We extended our studies using Redchief `Delicious' and `Empire', and, since BA is common to both Accel and Promalin, to study the effect of NAA-thinning sprays on Promalin-treated Redchief trees. NAA (10–15 mg·liter–1) and Accel (25–100 mg·liter–1) were applied to Redchief and `Empire' at 100-mm king fruit diameter (KFD). NAA interaction with Promalin was studied using Redchief. Promalin (1.5 pt/A) was applied as a single spray (80% king bloom, KB) and as a split application (0.75 pt/A, 80% KB and repeated at 10-mm KFD) with NAA (15 mg·liter–1) at 10-mm KFD. In `Delicious', 2% to 9% of the fruit from Accel-treated trees was <65 mm in diameter, compared to 11% for NAA alone. However, when NAA was applied with Accel, 22% to 30% of the fruit was <65 mm and percentage of large fruit (75 mm+) was reduced by 24% to 36%. There was no strong interaction for fruit size in `Empire', but the combination decreased yield. NAA applied to Promalin-treated `Delicious' increased percentage of small fruit dramatically (14% to 25%). No increase in small fruit was observed with Accel of Sevin.
Sprouting of axillary shoots was studied in nursery apple trees (Malus domestica Borkh) following defoliation and Promalin application. Both Promalin and defoliation stimulated lateral bud outgrowth. Promalin was more effective when applied to buds without the inhibition imposed by the subtending leaf. In the absence of the subtending leaves there was a decreased tendency for buds to sprout at lower node positions. Buds most responsive to Promalin were between those subtended by small, partially expanded leaves and those subtended by fully grown leaves.
A commercial formulation of N-(phenylmethyl) lH-purin-6-amine plus gibberellin A4A7 (Promalin) was applied to ‘Delicious’ apples (Malus domestica, Borkh.) from 1975 to 1978 in 2 geographic locations at rates of 12.5 to 50 ppm. Promalin at 25 ppm increased fruit weight, length/diameter ratio (L/D), and percent “typey” fruit at both a cool mountain location and at a lower warm elevation. The effect on “typiness” in the warm growing area did not appear to be of commercial significance, but the increase in fruit weight did appear significant under these conditions. Response varied with strain. Addition of a spray adjuvant, Triton CS-7, at the lower elevation, did not improve response. Rates of 12.5 or 25 ppm applied at petal fall of the “king” blossom appeared to be equally effective under high temperature conditions conducive to oblate fruits.
Low volume (concentrate) sprays to 7.5X (375 liters/ha) of BA applied at fixed rates (137 and 228 g/ha) with airblast equipment were as effective as full dilute applications (2800 liters/ha) for inducing branch development on young apple (Malus domestica Borkh.) trees. Sprays of BA or BA + gibberellin A4+7 (Promalin) applied in a spray solution based on tree-row-volume increased branching significantly at IX but failed to produce a response when applied as a concentrate spray at a fixed chemical rate. Cultivars responded similarly to changes in spray volume.
Asparagus (Asparagus officinalis)plants were sprayed and drenched with different concentrations of Promalin (0, 250, and 500 ppm) The varieties for the spraying experiment were `Mary Washington', `Emeral', `UC-157-F1', and `UC157F2'. Six replications for each treatment were used in a randomized complete-block design. The drenching experiment used two varieties (Mary Washington and UC-157-F2) with six replications of each treatment in a randomized complete-block design. Pots were numbered and labeled for each experimental unit. Plants (ferns) were counted and recorded in order to obtain the initial number of ferns before or after the spraying or drenching. In the spraying experiment, the plants were sprayed to run-off using a hand sprayer whereas; in the drenching experiment, 1000 mL or 1 L of the solution was used to drench each plant. The response to the chemical was measured in two ways: weekly stimulation of emergence of new-shoots and percent increase in final number of shoots over the initial number. In the spraying treatments differences were not found among the treatments used. In the drenching experiment with `Mary Washington' variety, a lower initial number of ferns at 250 ppm as compared to the 0 ppm of Promalin (8.82 to13.00) was observed. Differences for `Mary Washington' variety was not found for cumulative number of ferns on weeks 1, 2, and 3. However, the percent increase in number of ferns was higher for the 250 ppm as compared to the 0 ppm (174.55% to 78.14%). `UC-157-F2' showed no difference among the different concentrations. This indicates a difference in varietal response.
Easter lilies (Lilium longiflorum Thunb. `Nellie White') were placed at three spacings of about 11, 22, or 44 plants per square meter (plants/m2). Above canopy light intensities, measured weekly at noon, ranged from 107.3 to 704.5 μmol·s–1·m–2 and were not significantly different among spacings. Mid canopy light intensities ranged from 16.5 to 229.0, 43.0 to 458.5, and 77.5 to 535.3 μmol·s–1·m–2 at spacings of 44, 22 and 11 plants/m2, respectively. On February 5, 1996, three plants from the 22 plants/m2 spacing were sprayed with a solution of 0.5 ml·L–1 of 1.8% (a.i.) of each of N-(phenylmethyl)-IH-purine-6-amine and gibberellins A4A7; and on March 5, three additional plants from each spacing were similarly sprayed. Beginning 5 Mar., weekly counts were made of yellow and brown leaves on all treated and control plants. Average per plant numbers of brown leaves increased on control plants at all spacings but increased on treated plants only at the 11 plants/m2 spacing. On 25 Mar., control plants averaged 15.6, 12.1, and 15.3 brown leaves per plant at spacings of 11, 22, and 44 plants/m2, respectively, while plants treated on March 5 averaged 10.7, 9.0, and 10.7 brown leaves. Plants treated on 5 Feb. averaged 3.5 brown leaves per plant and had an average mid leaf length of 13.8 cm compared to about 10.5 cm for all other plants. Spacing had no effect on average yellow or brown leaves per plant. This study demonstrated that early applications of Promalin can reduce leaf senescence which may occur during forcing time before bud appearance to opening of first bud. Some leaf enlargement may occur on plants treated very early.
Paclobutrazol (PP333) is a promising new bioregulant for controlling size of trees and significantly reducing the need for dormant and summer pruning. ‘Delicious’ trees were treated with a high rate of PP333, which resulted in some smaller, flattened fruit with shorter pedicels. Application of either gibberellin A4+7 plus 6-benzylamino purine (Promalin) or gibberellin A3 (GA3) before or at full bloom increased fruit size, pedicel length, and leaf size on PP333-treated trees.