Abstract
There are many apple orchards in the Russian Federation where trees were trained with volumetric canopies; the vigor of these canopies must be suppressed. Prohexadione calcium (calcium 3-hydroxy-5-oxo-4-propionyl-cyclohex-3-enecarboxylate) was developed to inhibit the gibberellins biosynthesis to reduce vegetative growth. The study was done in the commercial orchard of “Planeta sadov” LLC in Michurinck district of Tambov Region (53°02’11.9 “N 40°29’29.9 “E). This research was aimed to evaluate the influence of prohexadione calcium on the length of one-year shoot growth, yield, and scab development on trees of vigorous apple cultivar ‘Sinap Orlovskii,’ planted 6 x 4 m (418 tr. ha-1). After 1.25 + 1.25 g ha-1 prohexadione calcium double treatment, the length of one-year shoots was 1.96 (2019) and 1.60 (2020) times less than Control 1 (without prohexadione calcium application and hand pruning) and 2,00 times less than in hand pruning treatment. The application of prohexadione calcium inhibited apple tree height and reduced the average height growth rate by 10.7% (2019) and 17.0% (2020). Growth retardant treatments stimulated significant yield increases and improved the commercial value of fruits. The enhance of scab protection improved under the influence of prohexadione calcium treatments. The application of growth retardant increased the alternate bearing index.
Highlights
Prohexadione calcium (Pro-Ca) belongs to a class of plant growth retardants – cyclohexanetriones [1] and inhibits biosynthesis of gibberellins in the range GA1-GA20 [2, 3]
Pro-Ca is relatively widely used in the South of Russia; the treatments stimulated a decrease of one-year shoot length and increased yield, mainly because of reducing alternate bearing [12]
This study aimed to research the influence of the growth retardant Pro-Ca on vegetative growth, yield, and opportunity for scab infestation reducing in the apple orchard of cv
Summary
Prohexadione calcium (Pro-Ca) belongs to a class of plant growth retardants – cyclohexanetriones [1] and inhibits biosynthesis of gibberellins in the range GA1-GA20 [2, 3]. There are reports that Pro-Ca treatments decreased scab (Venturia inaequalis) development [6]. It is possible because the application of Pro-Ca increases the concentration of specific flavonoids [8]. Pro-Ca's application reduces the internode length of one-year shoots but does not decrease their number [11]. Pro-Ca is relatively widely used in the South of Russia; the treatments stimulated a decrease of one-year shoot length and increased yield, mainly because of reducing alternate bearing [12]. The impact of treatments depends on rootstocks [15]
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