Articles
PROHEXADIONE-CALCIUM AFFECTS SHOOT GROWTH OF EVERGREEN SUBTROPICAL WOODY PERENNIALS DIFFERENTLY THAN DECIDUOUS TEMPERATE ZONE WOODY PERENNIALS – IS IT A CASE OF APPLES AND ORANGES?
Article number
884_29
Pages
249 – 256
Language
English
Abstract
Manipulation of vegetative shoot growth is an important factor in tree crop production.
Results with apple demonstrated that a single application of the gibberellin (GA)-biosynthesis inhibitor Prohexadione-calcium (P-Ca) (250 mg L-1) inhibited vegetative shoot growth for 4 weeks.
Prohexadione-calcium was tested for its capacity to inhibit growth of vegetative shoots after spring pruning of citrus and spring shoot growth of avocado. Eureka lemon (Citrus limon L.) and Washington navel orange (C. sinensis L.) trees were topped and hedged in mid-May and P-Ca (250 or 500 mg L-1) was applied 24 h later to the entire canopy to run off.
Prohexadione-calcium (250 or 500 mg L-1) reduced lemon shoot (elongation) growth by 30% for 5 weeks, but at 500 mg L-1 P-Ca reduced 2-year cumulative total yield and yield of commercially valuable large fruit (>6.1 cm transverse diameter) (kg and number per tree) compared to the untreated control (P<0.05). In contrast, P-Ca (250 and 500 mg L-1) had no effect on navel orange shoot length and reduced 2-year cumulative total yield (kilograms and fruit number) per tree by reducing the yield of small fruit (<6.9 cm) (P<0.05). The fruit-thinning effect of P-Ca (250 mg L-1) increased the 2-year cumulative yield (kg/tree) of large fruit (>7.5 cm transverse diameter) (P<0.05). Three foliar-applications of P-Ca (250 mg L-1) during bloom and fruit set of Hass avocado (Persea Americana Mill.) trees reduced the growth of the apical vegetative shoot of indeterminate floral shoots from May through June in the on-bloom year and April through July in the off-bloom year and increased fruit set from full bloom through August (P<0.05). Prohexadione-calcium (125 mg L-1) applied at the cauliflower stage of inflorescence development and again at full bloom significantly increased the 2-year cumulative yield of commercially valuable large fruit (>270 g/fruit) without reducing total yield (kilograms and number of fruit per tree) compared to the untreated control (P<0.05).
Results with apple demonstrated that a single application of the gibberellin (GA)-biosynthesis inhibitor Prohexadione-calcium (P-Ca) (250 mg L-1) inhibited vegetative shoot growth for 4 weeks.
Prohexadione-calcium was tested for its capacity to inhibit growth of vegetative shoots after spring pruning of citrus and spring shoot growth of avocado. Eureka lemon (Citrus limon L.) and Washington navel orange (C. sinensis L.) trees were topped and hedged in mid-May and P-Ca (250 or 500 mg L-1) was applied 24 h later to the entire canopy to run off.
Prohexadione-calcium (250 or 500 mg L-1) reduced lemon shoot (elongation) growth by 30% for 5 weeks, but at 500 mg L-1 P-Ca reduced 2-year cumulative total yield and yield of commercially valuable large fruit (>6.1 cm transverse diameter) (kg and number per tree) compared to the untreated control (P<0.05). In contrast, P-Ca (250 and 500 mg L-1) had no effect on navel orange shoot length and reduced 2-year cumulative total yield (kilograms and fruit number) per tree by reducing the yield of small fruit (<6.9 cm) (P<0.05). The fruit-thinning effect of P-Ca (250 mg L-1) increased the 2-year cumulative yield (kg/tree) of large fruit (>7.5 cm transverse diameter) (P<0.05). Three foliar-applications of P-Ca (250 mg L-1) during bloom and fruit set of Hass avocado (Persea Americana Mill.) trees reduced the growth of the apical vegetative shoot of indeterminate floral shoots from May through June in the on-bloom year and April through July in the off-bloom year and increased fruit set from full bloom through August (P<0.05). Prohexadione-calcium (125 mg L-1) applied at the cauliflower stage of inflorescence development and again at full bloom significantly increased the 2-year cumulative yield of commercially valuable large fruit (>270 g/fruit) without reducing total yield (kilograms and number of fruit per tree) compared to the untreated control (P<0.05).
Authors
L.C. Garner, Y. Zheng, T. Khuong, C.J. Lovatt
Keywords
avocado, Persea Americana ‘Hass’, lemon, Citrus limon ‘Eureka’, sweet orange, Citrus sinensis ‘Washington’ navel, vegetative and floral shoot growth, yield, pruning
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