• Korean Journal of Environmental Agriculture
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• v.32 no.3
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• pp.201-206
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• 2013

BACKGROUND: Kiwifruit, which was introduced to Korea in late 1970s, is a warm-temperate fruit tree, whose leaves are easily damaged by wind because of their large size. To produce high quality fruits, efficient windbreak is necessary to protect leaves until harvest. In Korea, typhoons from July onwards usually influence the production of kiwifruit. Damages from typhoons include low fruit quality in the current year and low flowering ratio the following year. This study was conducted to investigate the effect of early defoliation of kiwifruit vines from July to October on the regrowth of shoot axillary buds the current year and bud break and flowering the following year. METHODS AND RESULTS: Scions of kiwifruit cultivar 'Goldrush' were veneer grafted onto five-year-old Actinidia deliciosa rootstocks, planted in Wagner pots (13L) and grown in a rain shelter. Kiwifruit leaves in the proximity of leaf stalk were cut by lopping shears to simulate mechanical damage from typhoon since only leaf stalks were left when kiwifruit vines were damaged by typhoons. Kiwifruit vines were defoliated from July 15 to October 14 with one monthintervals and degrees of defoliation were 0, 25, 50, 75 and 100%. All experiments were conducted in the rain shelter and replicated at least five times. Defoliation in July 15 resulted in a high regrowth ratio of 20-40% regardless of degree of defoliation but that in August 16 showed only 5.8% of regrowth ratio in the no defoliation treatment; however, more than 25% of defoliation in August 16 showed 17-23% of regrowth ratio. In September 15, regrowth ratio decreased further to less than 10% in all treatments and no regrowth was observed in October 14. Percent bud break of all defoliation treatments were not significant in comparison to 64.7% in no defoliation except for 42.1% and 42.9% in 100% defoliation in July 15 and August 16, respectively. Floral shoot in the no defoliation treatment was 70.2% and defoliation of 50% or less resulted in the same or increased floral shoot ratio in July 15, August 16, and September 15; however, defoliation in October 14 showed no difference in all treatments. In flower number per floral shoot, 2-3 flowers appeared in no defoliation and only 1 flower was observed when the vines were defoliated more than 50% in July 15 and September 15. In October 14, contrary to the floral shoot ratio, flower number decreased with increased defoliation. CONCLUSION(S): Therefore, it is suggested that dormancy of 'Goldrush' axillary buds, was started in August and completed in October. The effect of defoliation on bud break of axillary buds the following year was insignificant, except for 100% defoliation in July 15 and August 16. From July 15 to September 15, floral bud ratio was significantly reduced when more than 50% of leaves were defoliated compared to no defoliation. Also, the number of flowers per flower-bearing shoot the following year decreased by less than 50% when compared to no defoliation, and this decrease was more prominent in September 15 than July 15 and August 16.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.1
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• pp.30-36
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• 1995

Pasture composed of about 30% botanical composition of white clover (Trijolium repem L.) is desirable in its productivity and quality. To get information on maintaining its productivity in the pasture, the experiment was canied out to determine the effect of infrequent, frequent defoliation or their alternation on change of its harvest yield and growth. Individual plants of Regal, Louisiana S-1, Grasslands Huia and Aberystwyth S184 were grown in 22cm plastic pot containing a 2 : 1 : 1 soil : sand : Peat moss mixture for 27 days after transplanting 50day seedlings raised on 3cm pots, and then all their fully expanded leaves are removed. Defoliation treatments were forced every 1 (CC, frequent), 4 week (RR, infrequent) or their alternations (CR, RC) after 8 weeks from the removal. To analyze the treatment effects, plants were sampled on 0 (the removal day), 4, 8, 12 and 16 weeks after the removal and seperated to leaves, petioles, stolons and roots. Each harvest yield of infrequent defoliation (RR) was higher than that of frequent defoliation (CC). Their alternations (RC, CR), however, forced fluctuation of the yield according to defoliation interval. Fraction weights from their altemations showed intermediate ones of infrequent and Frequent defoliation whose weights did the similar result to their harvest yields. Fraction and total dry weights per plant, shoot/root ratio were changed by relative span of defoliation interval, which resulted from the weights of leaves and petioles, removed parts. Root and total dry weight per plant of Regal were greater than the other cultivm in infrequent defoliation interval regardless of continuous or alternations. Productivity of white clover in pasture, therefore, can be controlled by alternation of infrequent and frequent defoliation or reverse.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.283-289
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• 2011

This study was conducted to examine the effects of defoliation treatment on the growth and yield of strawberry ($Fragaria{\times}ananassa$ cv. Maehyang and Seolhyang) during nursery period. Leaves of strawberry plantlet had been removed except two, three and four fully expanded leaves until planting date. As the intensity of defoliation was strong, the petiole length was reduced and overgrowth of strawberry plantlet was suppressed. Outer diameter of crown in defoliation treatments significantly decreased but inner diameter of crown was not significant. Number of primary roots of the 3 leaves or 4 leaves defoliation treatment generally tended to increase, but there was not significantly different among treatments. Fresh weight and leaf area in the defoliation treatments significantly decreased and the root weight were higher in partial 3 leaves or 4 leaves defoliation treatment but was not significantly different among treatments. Because T/R ratio decreased significantly as growth inhibition of above-ground part compared to underground part, it is considered easy to take rooting after plantlet plating. As the intensity of defoliation was strong, chlorophyll contents tended to decrease significantly. Reduction of the endogenous nitrogen by defoliation effectively led to promote floral differentiation at low temperature and short day condition. This promoted timing of budding and flowering and also induced uniform flowering after plantlet planting. Marketable fruit yield of 3 leaves defoliation treatment tended to be higher than the control.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.4
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• pp.389-396
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• 1994

Poor establishment of white dover (Trifolium repens L.) into grass-dominant pastures has been limited its availability. The experiment was done to clarify the effects of timing of initial defoliation, defoliation frequency on the regrowth and nodule formation of the clover cultivars during 28-day regrowing period. Individual plants of cv. Regal, Louisiana S-1 (La. S-1), Grasslands Huia (Huia) and Aberystwyth S184 (S184) were grown in containers until grown to unifoliolate, 1, 2, 4, or 8 trifoliolate stage, and then clipped to 1cm in height every 7 or 28 day for 28 days. To measure the effects, plants were sampled immediately after final harvest, and 1, 3, 7, 14 and 28 days after the harvest. Shoot, root dry weight and biomass were reduced with earlier, more frequent defoliation or shorter regrowing period. In frequent defoliation shoot dry weight and biomass were increased with delayed initial defoliation while in less frequent defoliation steeply done when initial defoliation was delayed to 4 trifoliolate stage. Shoot /Root ratio inclined with more frequent defoliation or lengthened regrowing period, and was greater in initial defoliation of unifoliolate to 2 trifoliolate than the others. Although nodules no. per plant declined with earlier or more frequent defoliation, the effect disappeared to some extent after 14-day regrowth. In comparison with the others, Regal had the highest shoot. dry weight and biomass to 2 trifoliolate stage while S184 did the most nodules regardless of defoliation timing. On 7-day after last defoliation nodule formation of Regal, Huia and S184 but on 28-day after last defoliation that of La. S-1, Huia and S184 was positively correlated to shoot and root dry weights upto 2 trifoliolate stage. On the former day, however, that was negatively correlated to Shoot /Root ratio upto 1 trifoliolate stage although on the latter day it was not, meaning that in addition to more frequent defoliation earlier defoliation was harmful in nodule formation of white clover.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.229-234
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• 2012

BACKGROUND: The fruit quality and flowering characteristics of Kiwifruit (A. deliciosa cv. Hayward) in the following year is known to be affected by the extent and timing of defoliation of the current year. In korea, the production of kiwi, which is a perennial, straggling deciduous warm-temperate fruit, is often restricted by wind damage due to typhoons resulting to defoliation at the middle season of its growing period. In this paper, we report the effect of the different timing of defoliation and severities at the current season to the kiwifruit quality. METHODS AND RESULTS: Twenty seven-year-old 'Hayward' trees grown under polyethylene film rain-shelter were defoliated in different days from August to September at seven day-intervals. In each day, 0, 25, 50, 75 and 100% of leaves were removed from the trees. Fruits from each treatment were classified into four floating types (L: lying in bottom, S: standing on bottom, F: floating and SF: floating at the surface of water) by submerging them into tap water. Defoliation of kiwifruit trees in August and September caused air holes in locules of inner pericarp. Increased number of air hole in locules of a fruit was observed in floating types F and SF, and most of the air holes were located in stem end. The defoliation of trees in August significantly reduced the ratio of L-floating type fruits, which have the least number of locule air holes. The extent of defoliation also affected the distribution of the four types, the more leaves removed, the less L-floating type fruits harvested. The weight of fruits from trees defoliated in August was lower than that of fruits from September. Soluble solids content decreased as the number of locule air holes increased. Negative correlations were observed between the extent of defoliation and the weight and soluble solids content of fruits. CONCLUSION: Early defoliation effect on kiwifruit locule air hole occurrence and fruit quality were more severe in August than in September. And also if the defoliation severity is over 25%, severe fruit quality reduction expected to happen due to increase of fruit locule air hole in the inner pericarp.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.20-27
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• 1982

Two rice varieties were planted and four degrees of defoliated tiller num ber ratio and another four levels of defoliation-panicle removal tiller number ratio were made at heading stage of know the possibility of translocation of photosynthetic products between tillers during grain filling stage of rice plant. The more tillers defoliated in a hill, the less matured grain ratio and the less grain weight per panicle of normal tillers were found. But the matured grain ratio and the grain weight per panicle of tillers defoliated partly in a hill showed higher than those of tillers of completely defoliated plant. No differences of the matured grain ratio and the grain weight per panicle were found between different levels of defoliation-panicle removal tiller number ratio in a hill. But the matured grain ratio and the grain weight per panicle of tillers of completely defoliated plant were significantly lower than those of tillers of partly defoliation-panicle removal treatments. These results indicated that the translocation of photosynthetic products between tillers was possible during grain filling period in rice plant. Source-sink relationship can be applied to interpret the result obtained in this study.

• Journal of Bio-Environment Control
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• v.10 no.2
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• pp.118-119
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• 2001

This experiment was carried out to examine the effects of foliar applications of 100 mg.L$^{-1}$ ethephon mixed with different calcium formulae (10,000 mg.L$^{-1}$ Clef-non, 2,000 mg.L$^{-1}$ Cell-bine, 2,000 mg.L$^{-1}$ Hicalux, and 2,000 mg.L$^{-1}$ calcium acetate monohydrate) on the rind coloration, defoliation and fruit quality of satsuma mandarin cultivated in the plastic greenhouse. Foliar applications of ethephon alone or in mixture with either Clef-non, Cell-bine, Hicalux or calcium acetate monohydrate demonstrated that increased 'a'value of peel chromaticity as compared to the control. The treatments encouraged fruit colour and allowed the harvest date to be predicted. The defoliation ratio decreased considerably by foliar applications of ethephon mixed with Cell-bine or Hicalux. The sugar content of fruit increased by 1.6, 1.54, and 1.54$^{\circ}$Bx with the foliar applications of ethephon, ethephon+Clef-non, and ethephon+Cell-bine, respectively. With the foliar applications of ethephon in mixture with Cell-bine, fruit coloration was accelerated. defoliation was delayed, and fruit quality was improved.

• Horticultural Science & Technology
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• v.16 no.4
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• pp.514-516
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• 1998

This study was conducted to observe the effects of urea foliar spray to replace soil fertilization on defoliation ratio, shoot growth and fruit setting in satsuma mandarin (Citrus unshiu Marc.). Twice foliar sprays of 1% urea after harvest increased N and chlorophyll contents in leaves, and decreased defoliation during the winter season. The growth of the ovary and spring shoot was stimulated by the twice 0.8% urea foliar spray around the time of bud emergence. In addition, the treatments increased the number of flowers and fruit setting, but didn't influence fruit quality.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.4
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• pp.38-44
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• 1979

$^14$C-sucrose was labeled on detached panicles and $^14{CO}_2$ on flag leaves or panicles of intact plants to study grain sink activity in spring oats cultivar Pennfield. Defoliation and emasculation experiment was conducted to study source-sink relationship during grain filling. Specific activity of groat rose up to 15 days after anthesis and declined rapidly to 18 days. Daily gain of groat wt. matched closely with specific activity of. groat during grain filling. Primary groats were higher in specific activity of groat than secondary groats.$^14{CO}_2$ exposure on panicle was three times higher in specific activity of groat than $^14{CO}_2$exposure on flag leaf. In the defoliation and emasculation experiment, groat wt. of Pennfield oats decreased as ratio of source/sink decreased. Half number of spikelets with half leaf area was no different in groat wt. compared to control, but normal number of spikelets with zero leaf area was decreased 16% in groat wt., indicating a significant compensation by green area on panicle.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.3
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• pp.151-161
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• 2016

This study was conducted to find out influence of dormancy level and carbon concentration on freezing hardiness in bourse shoot of 'Fuji' apple tree. Bourse shoot of 'Fuji' adult apple tree grafted on M.26 and M.9 rootstocks were used as experimental materials. Dormancy levels of bourse shoot were categorized according to the periods as follows the internal dormancy (late January), the early days after internal dormancy breaking (early February), the late days after internal dormancy breaking (late February), the bud break (late March), and the full bloom (late April). Chilling temperatures with bourse shoot were ranged from 0 to $-40^{\circ}C$. Also, the freezing hardiness according to carbon concentrations were investigated on 'Fuji'/M.9 apple tree that defoliated severely by Marssonina blotch (defoliation) and that of below the average 20 cm in shoot length through heavy crop load (weakness). Results showed that freezing hardiness of bourse shoot may become weaker after internal dormancy breaking. There was no differences in the carbon concentration of bourse shoot of 'Fuji' apple tree grafted on M.9 and M.26, so may be resulted in no difference in freezing hardiness both of bourse shoot grafted on M.9 and M.26 rootstock. Carbon concentration in bourse shoots with weakness and C/N ratio in bourse shoots with defoliation were lower than that of healthy. It may be shown that the freezing hardiness of defoliation and weakness were weaker than that of healthy.