scholarly journals Physiological Changes during Maturation, Ripening, and Storage of Asian Pears Grown in Southeastern United States

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 816G-817
Author(s):  
Nihal Rajapakse ◽  
William C. Newall
Keyword(s):  
United States ◽  
Ethylene Production ◽  
Southeastern United States ◽  
Fruit Size ◽  
Physiological Changes ◽  
Mature Fruit ◽  
Immature Fruit ◽  
Early Maturation ◽  
Nonclimacteric Fruit ◽  
Harvest Maturity

Morphological and physiological changes during maturation and ripening of eight Asian pear cultivars grown in the southeastern United States were evaluated. Fruit size increased throughout maturation. Flesh firmness decreased as fruit matured and averaged ≈30 to 35 N at harvest maturity. The average TSS in mature fruit ranged from 10% to 13%, with `Shinko' having the lowest and `Shinsui' having the highest. TSS increased during 4 weeks of storage at 1C, but the increase was greater in immature fruit than in mature fruit. Respiration rate declined as fruit matured. Ethylene production was low in `Hosui', `Kosui', `Nijisseiki', `Shinseiki', `Chojuro', and `Shinko' fruit. Mature `Ichiban' and `Shinsui' fruit produced high amounts of ethylene. `Kosui', `Shinsui', `Chojuro', and `Ichiban' fruit showed a climacteric rise in respiration and ethylene production at 20C, while `Hosui', `Nijisseiki', `Shinseiki', and `Shinko' behaved as nonclimacteric fruit. Ethylene production by 1C-stored `Kosui', `Shinsui', `Chojuro', and `Ichiban' fruit was increased on removal to 20C. Glucose and fructose were low during early maturation but sharply increased ≈80 to 85 days after full bloom (DAFB). Sucrose was low in immature fruit but accumulated rapidly late in maturation ≈100 to 107 DAFB. In mature `Hosui', `Kosui', `Nijisseiki', `Shinsui', `Shinko', and `Ichiban' fruit, fructose was the predominant sugar, while in `Shinseiki' and `Chojuro' fruit, sucrose was the predominant sugar.

scholarly journals Severity of Scab and its Effects on Fruit Weight in Mechanically Hedge-Pruned and Topped Pecan Trees

Plant Disease ◽  
2017 ◽  
Vol 101 (5) ◽  
pp. 785-793 ◽  
Author(s):  
Clive H. Bock ◽  
Michael W. Hotchkiss ◽  
Tim B. Brenneman ◽  
Katherine L. Stevenson ◽  
William D. Goff ◽  
...  
Keyword(s):  
United States ◽  
Shoot Growth ◽  
Southeastern United States ◽  
Fruit Weight ◽  
Tree Size ◽  
Mature Fruit ◽  
Air Blast ◽  
Sample Height ◽  
Tree Canopies

Scab is the most damaging disease of pecan in the southeastern United States. Pecan trees can attain 44 m in height, so managing disease in the upper canopy is a problem. Fungicide is ordinarily applied using ground-based air-blast sprayers. Although mechanical hedge-pruning and topping of pecan is done for several reasons, improved management of scab is an important reason in the humid, wet Southeast. Resulting shoot growth on cut limbs of susceptible cultivars could lead to more severe scab. In three experiments over three years, we explored the effect of hedge-pruning trees to ∼12 to 14 m compared with non-hedge-pruned trees. All trees received fungicide treatments (air-blast sprays and ≤3 aerial applications). Hedge-pruning either had no effect, or increased or decreased scab severity only slightly on leaflets, immature, or mature fruit (a –9.95 to +14.63% difference in scab severity compared with the control). However, height in the canopy invariably had a large and significant effect on scab severity, and amounted to a 0.05 to 73.77% difference in severity between the lowest and highest sample in the canopy. Fruit weight depended on sample height, with fruit most often weighing less when collected at greater sample heights. A robust relationship between fruit weight and scab severity was found at the highest sample heights where scab was also most often severe (R2 = 0.21 to 0.67, P < 0.0001). Hedge-pruning and topping pecan tree canopies to manage tree size will enable better fungicide coverage, reducing risk of a scab epidemic as more of the canopy is assured efficacious fungicide spray coverage.

scholarly journals Association between Fruit Development and Mature Fruit Drop in Huanglongbing-affected Sweet Orange

HortScience ◽  
2020 ◽  
Vol 55 (6) ◽  
pp. 851-857
Author(s):  
Lisa Tang ◽  
Sukhdeep Singh ◽  
Tripti Vashisth
Keyword(s):  
Fruit Development ◽  
Sweet Orange ◽  
Water Status ◽  
Fruit Size ◽  
Substantial Reduction ◽  
Fruit Growth ◽  
Mature Fruit ◽  
Callose Deposition ◽  
Immature Fruit ◽  
Fruit Drop

In the past decade, FL citrus industry has been struck by Huanglongbing (HLB), a disease caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas). Besides tree decline, HLB causes a sharp increase in mature fruit drop before harvest, leading to a substantial reduction in citrus production. The aim of the study was to provide insights in HLB-associated mature fruit drop. For HLB-affected ‘Valencia’ and ‘Hamlin’ sweet orange (Citrus sinensis), trees exhibiting severe symptoms (“severe trees”) had a significantly higher rate of mature fruit drop compared with mildly symptomatic ones (“mild trees”). Interestingly, dropped fruit were smaller than those still attached to tree branches regardless of the symptom levels of trees; overall, fruit of severe trees were smaller than mild trees. The result suggests a negative effect of HLB on fruit growth that may lead to a high incidence to drop subsequently at maturity. This possibility is further supported by the difference in immature fruit size as early as 2 months after bloom between severe and mild trees. Although HLB-triggered phloem plugging due to callose deposition in citrus leaves, which results in disrupted carbohydrate transport, has been documented in literature, the results of the histological analysis demonstrated no consistent pattern of callose deposition in the mature fruit pedicel in relation to the drop incidence. Additionally, sugar concentration in juice was not significantly different between dropped and attached fruit, providing evidence that carbohydrate shortage is not the case for dropped fruit and thus not the predominant cause of HLB-associated mature fruit drop. Notably, the midday water potential was significantly lower for severe than mild trees during the preharvest period (2 weeks before harvest of the current crop) in late March, which was also the second week after full bloom of return flowering. This suggests that altered tree water status due to HLB might limit fruit growth during the initial stage of fruit development (immediately after flowering) and/or increase the incidence of mature fruit abscission, leading to elevated preharvest fruit drop. Together, the results suggest that in the presence of HLB, strategies to increase fruit size and minimize additional stresses (especially drought) for the trees may improve mature fruit retention.

scholarly journals Developmental Changes in Carbohydrate Composition of Asian Pear Cultivars Grown in the Southeastern United States

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 684a-684
Author(s):  
Nihal C. Rajapakse ◽  
William C. Newall
Keyword(s):  
Soluble Sugars ◽  
Developmental Changes ◽  
Sugar Composition ◽  
Pear Fruit ◽  
Full Bloom ◽  
Mature Fruit ◽  
Total Soluble Sugars ◽  
Immature Fruit ◽  
Early Maturation ◽  
Asian Pear

Changes in sugar composition during maturation and ripening of eight Asian pear cultivars were evaluated. Total soluble sugars (TSS) increased gradually throughout the maturation and averaged 10% to 13% in mature fruit. All cultivars, except `Shinko' and `Nijisseiki', had accumulated ≥10% TSS by 100 days after full bloom (DAFB). Starch accumulated during early stages of Asian pear fruit development but decreased as the maturity progressed coinciding with the rise in soluble sugars. Sorbitol, a sugar alcohol, was predominant in immature fruit and accounted for 35% to 60% of TSS fraction depending on the cultivar. Fructose rapidly increased during early maturation. Glucose increased during early maturation, but the increase was much smaller than that of fructose. Sucrose was low (<4%) in immature fruit but accumulated rapidly late in the maturation and continued to increase until harvest. In mature `Hosui', `Kosui', `Nijisseiki', `Shinsui', `Shinko', and `Ichiban' fruit, fructose was the predominant sugar which accounted for 47% to 60% of the TSS fraction. Glucose and sucrose accounted for 13% to 17% and 7% to 12%, respectively, in those cultivars. In mature `Shinseiki' fruit, sucrose was the predominant sugar (44% of TSS), while fructose and glucose accounted for 33% and 8%, respectively. Sucrose and fructose were present in equal amounts (29%) in mature `Chojuro' fruit. Late accumulation of sucrose in Asian pear cultivars suggest that sufficient time should be allowed before harvesting to obtain sweeter fruit.

scholarly journals 468 Effect of Hydrogen Cyanamide (Dormex) and Ethephon (Ethrel) on Fruiting of `Surecrop' Peaches

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 525C-525
Author(s):  
Arlie A. Powell ◽  
James Pitts ◽  
Bobby Boozer
Keyword(s):  
United States ◽  
Experimental Design ◽  
Southeastern United States ◽  
Fruit Size ◽  
Early Spring ◽  
Late Winter ◽  
Crop Loss ◽  
Hydrogen Cyanamide ◽  
Fall Application ◽  
Whole Tree

Early flowering of peach in the southeastern United States can result in annual crop loss as a result of late winter-early spring freezes. In peach and other prunus, a fall application of ethephon delays flowering several days; however, delayed harvest and smaller fruit size of certain varieties may occur. Hydrogen cyanamide replaces the late stage of chilling in peach but can also advance bloom and harvest date while maintaing or enhancing fruit size. A randomized complete-block experimental design using 13-year old `Surecrop' trees was used to evaluate whether hydrogen cyanamide could offset the delayed harvest and smaller fruit size disadvantages of using ethephon without advancing bloom dates. Treatment combinations of ethephon (at 20%, 50%, and 90% of required chilling) and hydrogen cyanamide (at 90% to 100% of required chilling) were applied as whole-tree foliar sprays to near point of drip. Although not significant, there were trends toward hydrogen cyanamide overcoming both smaller fruit size and delayed harvest induced by ethephon. This agrees with an earlier study using `Redhaven'. Dormex negated the late flowering effects of ethephon applied at 20% chilling but did not cause flowering earlier than the control.

scholarly journals Effect of Hydrogen Cyanamide (Dormex) on Replacing Lack of Chilling in Kiwifruit (Actinidia deliciosa)

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 845E-845
Author(s):  
Arlie A. Powell ◽  
Ed Tunnell
Keyword(s):  
United States ◽  
Gulf Coast ◽  
Southeastern United States ◽  
Maximum Yield ◽  
Fruit Size ◽  
Test Area ◽  
Hydrogen Cyanamide ◽  
Chilling Hours ◽  
Female Flowers ◽  
Winter Chilling

It has been shown that the `Hayward' kiwifruit requires ≈1000 chilling hours for satisfactory production of female flowers, leading to full cropping in the southeastern United States. Part of the area along the Gulf Coast frequently suffers from inadequate winter chilling, resulting in poor cropping of `Hayward'. Studies were conducted over a 4-year period in a mature `Hayward' planting near the Gulf Coast to evaluate the efficacy of hydrogen cyanamide sprays in replacing lack of chilling and improving cropping. Rates of 2%, 3%, and 4% (v/v) of 50% Dormex significantly increased yield, with the highest rate providing the maximum yield. Fruit size and overall fruit quality from Dormex treatments were good. Dormex sprays performed quite well when only 600 to 700 chilling hours were received in the test area.

Physico-Chemical and Physiological Changes during Fruit Development and Ripening of Five Loquat (Eriobotrya Japonica Lindl.) Cultivars

2003 ◽  
Vol 9 (1) ◽  
pp. 43-51 ◽  
Author(s):  
A. Amorós ◽  
P. Zapata ◽  
M. T. Pretel ◽  
M. A. Botella ◽  
M. Serrano
Keyword(s):  
Fruit Development ◽  
Ethylene Production ◽  
Sugar Content ◽  
Fruit Size ◽  
Fast Growth ◽  
Eriobotrya Japonica ◽  
Content Increase ◽  
Physiological Changes ◽  
Physico Chemical ◽  
Sigmoid Curve

Physico-chemical and physiological changes during development and ripening of five loquat cultivars ( Eriobotrya japonica Lindl., cv. Algerie, Cardona, Golden, Magdall and Peluche) were determined. Fruit growth showed a sigmoid curve in all loquat cultivars. A good relationship between duration of fast growth phase and fruit size was found. In addition, a positive correlation was also established between seed number and fruit size, and between seed weight and both fruit and flesh weight. Colour changes, sugar content increase and the decrease in fruit firmness and organic acids started simultaneously when loquat fruits were in the phase of fast growth, and at about 70-80% of their final weight. These physico-chemical changes related to fruit ripening coincided with an increase in both ethylene production rate and free and total 1-aminocyclopropane-1 -carboxylic acid (ACC) content in the flesh. In addition, a small respiration peak associated with ripening was also detected. These results indicated that loquat fruits of all five studied cultivars showed a pattern of ripening in the tree that could be classified as climacteric, with relatively low ethylene production evolving at an early phase of fruit development.

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