The post-harvest ripening of water stressed banana fruits

SUMMARY

Maintaining banana fruit in a low humidity environment accelerated fruit ripening. This was reflected in an earlier increase in respiration and ethylene production and more advanced peel colour and pulp sugars. At the end of the trial the fruit kept in low humidity were yellow with green tips (stage 5) whereas those kept at high humidity were still green (stage 1-2). Fruit kept at low humidity did not show a large increase in pulp ethylene production compared with the fruits stored at high humidity. This difference occurred despite a large increase in the 1-aminocyclopropane-l-carboxylic acid (ACC) content of both samples, with the low humidity fruit preceding the high by two days. The peel ethylene production of the low humidity stored fruit increased dramatically as the fruit ripened, coinciding with an increase in ACC. The ACC oxidase activity of the peel reflected the ethylene production with a large increase in the low humidity stored fruit and a later, smaller increase in the high humidity stored fruit. The ACC oxidase activity of the pulp of both low and high humidity stored fruit increased gradually during storage. The changes in ethylene production are discussed with reference to banana ripening being regarded as co-ordinated by pulp ethylene production while the peel is passive, depending on pulp ethylene production for degreening.     

Physical and cellular structure changes of Rastali banana (Musa AAB) during growth and development

A study on the physical and physiological characteristics of Rastali bananas (Musa AAB) was carried out throughout the 12 weeks after emergence of the first hand to determine the optimum growth stage of Rastali bananas. The fruit length and diameter followed a trend similar to that observed in fruit fresh weight throughout fruit development, and three physiological stages (S1–S3) of sigmoid growth were identified. The growth rate was slow during S1 (1st to 4th week), rapid during S2 (5th to 10th week) and remained constant during S3 (11th and 12th week). Peel cells underwent periclinal growth, which was accompanied by an increase in fruit peel and pulp thickness as the fruit developed. Moreover, the pulp colour became more vivid and yellow as the fruit developed. The peel moisture content decreased while pulp moisture content increased during fruit growth and development. The pulp firmness increased from the first until seventh week, and it decreased from the seventh week until twelfth week of the experiment. Carbon dioxide (CO₂) production was the highest at S1. However, CO₂ production declined until the 10th week and remained constant at a low level of 50 mL kg⁻¹ h⁻¹ during S3. Ethylene (C₂H₄) could not be detected throughout fruit growth and development. Thus, Rastali bananas showed physiological maturity at week 11 and week 12 after emergence of the first hand with constant fruit growth.     

Influence of 1-methylcyclopropene on pectic enzyme activities,gene expression,and cell wall modification in papaya (Carica papaya cv. ‘Sunrise’) fruit

SUMMARY

‘Sunrise’ papaya fruit harvested at two stages of maturity [colour break (< 10% yellow peel colour) and 25% yellow peel colour] were treated with 100 nl l^–1 1-methylcyclopropene (1-MCP) to determine its effects on ripening, on the activities and levels of gene expression of polygalacturonase (PG), pectin methyl esterase (PME), and βgalactosidase ( βGal), and on the degradation of cell wall components. 1-MCP delayed ripening and the onset of the climacteric, although the peak in the respiration rate was almost the same as that in untreated control fruit. Colour-break fruit treated with 1-MCP exhibited a continuous increase in ethylene production, but at a lower rate than in control fruit. Consequently, 1-MCP-treated fruit ripened with a concomitant reduction in firmness, which was accompanied by an increase in PG and βGal enzyme activities and gene expression. On the other hand, fruit treated with 1-MCP at the 25% yellow stage exhibited lower levels of ethylene production and developed pulp with a rubbery texture at the ripe stage which was attributed to reduced PG, βGal, and PME enzyme activities and gene expression. This was consistent with the higher level of cell wall polysaccharides measured in 1-MCP-treated fruit. The above results indicated that ‘Sunrise’ papaya fruit can be treated with 1-MCP at the colour break stage since they have a greater capacity to recover from the effects of 1-MCP than fruit treated at the 25% yellow stage.     

Biochemical and physiological changes during chlorophyll degradation in lime (Citrus aurantifolia Swingle cv. ‘Paan’)

Summary

Lime (Citrus aurantifolia Swingle cv. ‘Paan’) native to South East Asia, has a distinct flavour and quality characteristics. Maintenance of the green colour in the peel of lime is a desirable quality attribute during storage. Post-harvest chlorophyll degradation in lime was studied in fruit stored at room temperature (30°C) at a relative humidity (RH) of 70 – 85%. Within 7 d of storage, the total chlorophyll content decreased to 53.9% of its initial level. The highest chlorophyllase activity (1.68 units mg^–1 protein) was observed after 4 d of storage and declined thereafter. Peroxidase activity differed from chlorophyllase activity and increased significantly to 6.25 units mg^–1 protein after 9 d of storage, (i.e., at the late maturity stage). Respiration rate and 1-aminocyclopropene-1-carboxylic acid (ACC) oxidase activity did not significantly affect the chlorophyll degradation process in lime.The total nitrogen content of lime peel was inversely correlated with its chlorophyll content. A higher soluble protein content was observed in yellow peel than in mature green peel. A colour index chart was developed for maturity stages 1–4 in lime based on peel colour changes from mature green to full-yellow, and its correlation with chlorophyll content and fruit quality attributes.     

甜橙果实膳食纤维与PG、Cx活性的研究

以红肉脐橙、纽荷尔脐橙和塔罗科血橙果实为试材,测定了果实发育过程中总膳食纤维（TDF）、可溶性膳食纤维（SDF）、不溶性膳食纤维（IDF）、总果胶（TP）、原果胶（protopectin）、水溶性果胶（WSP)、纤维素（CEL）、半纤维素（HC）和木质素（lignin）等的含量以及多聚半乳糖醛酸酶（PG）和纤维素酶（Cx）活性。结果表明：3个品种果实发育过程中总膳食纤维含量变化趋势基本一致,随着果实的成熟含量逐渐减少;果肉中,塔罗科血橙TDF含量最少,纽荷尔次之,红肉脐橙最多;IDF含量变化趋势与TDF基本一致,而SDF与TDF相反。果实发育过程中果胶含量呈下降趋势,果肉中表现较果皮明显;WSP含量随着果实成熟不断增加。随着果实的发育,木质素和HC含量急剧下降,且果肉中木质素和HC含量与Cx活性呈显著负相关;PG活性在果实发育前期较低,随着果实的成熟迅速增加,在11月初达到最大值后急剧下降。     

糯米糍荔枝裂果与内源激素变化的关系

以易裂荔枝品种糯米糍为材料,研究了果实发育前期（ 即果皮发育期） 裂果与正常果、裂果多与裂果少的植株果实内源激素变化,结果表明,在果实发育前期果皮中的细胞分裂素（ＣＴＫ） 、生长素（ＩＡＡ） 含量较高,说明果实发育前期果皮主要以细胞分裂、加厚生长为主。比较裂果多与裂果少植株上的正常果实,裂果多的树生长促进类物质（ＩＡＡ＋ ＧＡＳ＋ ＣＴＫ） 含量较高,果肉尤为如此。初步认为,裂果与内源激素变化密切相关。还讨论了内源激素比例与裂果的关系。     

枣裂果机制研究

采用浸水模拟降雨、石蜡制片和显微测量技术,以极易裂、中抗和极抗裂品种为材料,测量枣果表皮厚度、梗洼下空腔、果肉空腔和果肉细胞大小及其变化,探讨成熟期枣裂果机制。结果表明,不同裂果等级枣品种之间表皮厚度差异极显著,且极抗裂品种表皮最厚,极易裂品种最薄,中抗品种居中,表皮越厚越抗裂。不同裂果等级枣品种之间梗洼下空腔与枣果比率差异极显著,极抗裂品种比率最小(0.24%～0.26%),极易裂品种最大(0.62%),梗洼下空腔越小越抗裂。不同裂果等级枣品种之间果肉空腔大小差异极显著,极抗裂品种最小(3 380.82～3 879.12μm2),极易裂品种最大(9 300.49～10 809.86μm2),果肉空腔越小越抗裂。果肉细胞大小没有显著差异,但果肉细胞的吸水速显著不同,极易裂品种果肉细胞吸收最快,极抗裂品种最慢,中抗品种居中,果肉细胞吸水越慢越抗裂。这些研究表明枣果表皮厚度、梗洼下空腔、果肉空腔和果肉细胞的吸水速度共同决定了枣的裂果程度。     

Leaf-to-fruit ratio affects water and dry-matter content of mango fruit

Summary

Changes in water and dry-matter content of developing mango fruit (Mangifera indica L. ‘Lirfa’) were investigated over a single season in Réunion Island, along with the effects of leaf:fruit ratio (10, 25, 50, 100 and 150 leaves per fruit on girdled branches). As the fruit developed, about 8–13% of fruit water weight was in the peel compared with 78–86% in the pulp and 6–9% in the stone. When the data were expressed on a dry-weight basis, 12–20% was in the peel, 60–70% was in the pulp and 18–20% in the stone. At harvest, larger fruit, on treatment 100, had a higher proportion of weight in the pulp. Good relationships between water and dry weight of each fruit component were found, regardless of the treatment. They showed that the rate of water accumulation decreased when the dry weight increased and that the dry-matter content increased as the fruit developed as well. Increasing leaf:fruit ratio to 100 leaves per fruit improved fruit yield by 300 g and pulp dry-matter content by 6%, for a total of 550 g and 20% at harvest. Fruit quality as estimated by pulp dry-matter content could be calculated easily during the changes in fruit weight over the season. Moreover, this indicator could be useful to assess the maturity of mango fruit.     

抗裂与易裂枣内源激素含量和细胞壁代谢相关酶活性比较

 以枣抗裂果品种‘圆铃枣’和易裂果品种‘俊枣’为材料,测定了果实生长发育曲线、果 形指数及种子败育率,并对果皮、果肉、种子中内源激素含量及果皮、果肉中细胞壁代谢相关酶的活性 进行了检测。结果表明,‘俊枣’果形指数和种子败育率均显著高于‘圆铃枣’。果实发育后期‘俊枣’ 果皮中的GA3 含量、果肉中的IAA 含量明显高于‘圆铃枣’,而‘圆铃枣’果肉及种子中的ABA 含量高 于‘俊枣’;‘俊枣’果肉及种子中（GA3 + IAA + ZT）/ABA 的比值在整个果实生长发育期均高于‘圆铃 枣’。果实生长发育后期‘俊枣’果皮中的果胶酶及纤维素酶活性高于‘圆铃枣’,且‘俊枣’果肉中的 POD 及PPO 活性也较高。以上结果显示,枣果实生长发育后期易裂品种‘俊枣’果肉中的IAA 积累较多, 而抗裂品种‘圆铃枣’果肉及种子中ABA 含量显著高于易裂品种;易裂品种‘俊枣’果肉及种子中（GA3 + IAA + ZT）/ABA 的比值较高,果皮中的果胶酶、纤维素酶活性影响裂果的发生,其POD 及PPO 活性相 对较高。     

Physico-chemical changes during growth of persimmon fruits in the East Mediterranean climate region

Physico-chemical changes were monitored during growth of pollination variant non-astringent ‘Harbiye’ persimmon fruits (Diospyros kaki L.) grown at low or high altitude of the East Mediterranean Region of Turkey for two growing seasons (2001–2002 and 2002–2003). Fruit growth in diameter followed a typical double sigmoid curve, consisting of two rapid growth stages, stage I and stage III, separated by a period of slow growth (stage II) at both altitudes. The durations of stages I, II and III were 105–119, 21–35 and 21–42 days, respectively, at low and high altitude. ‘Harbiye’ persimmons showed significant decreases in soluble tannin concentration and total carotenoid content during stage I. At the end of stage I, ‘Harbiye’ persimmons became non-astringent. Stage II was characterized with slow growth, the beginning of acid degradation and a significant increase in total sugars, especially in the sucrose component. At end of stage II, the fruit began to turn yellow-orange, indicating the occurrence of colour break. The greatest increase in total soluble solids (TSS) content occurred in the final month before harvest during stage III when pronounced changes in skin colour and softening of fruits were observed. The 175 and 168 days after full bloom (DAFB) at low and high altitudes, respectively, are appropriate timing for harvest of the ‘Harbiye’ persimmon fruits in the East Mediterranean region. At these stages, ‘Harbiye’ persimmon fruits reached the best quality for consumers.     

Involvement of 1-methylcyclopropene in ripening of harvested mei (Prunus mume) fruit

Summary

Harvested mei (Prunus mume) fruit were stored at 20°C after exposure to 500 nl l^–1 1-methylcyclopropene (1-MCP) for 8 h. Firmness, peel colour, chlorophyll content, chlorophyllase activity, soluble solids content (SSC), titratable acidity (TA), respiration and ethylene production, and cell wall hydrolysis enzyme activities were monitored to determine the efficacy of 1-MCP treatment in delaying mei fruit ripening compared to untreated control fruit. Results showed that control ‘daqinghe’ mei fruit displayed typical climacteric patterns of respiration and ethylene production. Peak CO₂ production and ethylene production were observed after 6 d. Fruit softening was accompanied by a progressive decrease in colour parameters expressed as hue angle (h°), chlorophyll content, SSC, TA and increases in chlorophyllase, pectin methylesterase (PME) and polygalacturonase (PG) activities. 1-MCP treatment prior to the climacteric increase significantly delayed the onset of the climacteric peaks of CO₂ and ethylene production. These delays were associated with reductions in fruit softening, consistent with delaying the activities of PME and PG. Fruit treated with 1-MCP exhibited less peel colour change from green-to-yellow because of their lower levels of chlorophyllase activity and less chlorophyll breakdown. Moreover, 1-MCP treatment also significantly retarded reductions in SSC and TA compared with control fruit. The shelf-life of mei fruit ripening was increased by 4 d following 1-MCP treatment. Thus, 1-MCP treatment can markedly extend the post-harvest life of ‘daqinghe’ mei fruit.     

Effects of different crop loads and thinning times on yield,fruit quality,and return bloom in Malus × domestica Borkh. ‘Elstar’

Summary

‘Elstar’ is the latest-maturing commercial apple cultivar grown in Norway, with high fruit quality when properly managed. In May 2006, an experiment with four different crop loads [2, 4 ,6, or 8 flowers or fruitlets cm^–2 trunk cross-sectional area (TCSA), respectively] was established at two different stages [first bloom (FB), or 20-mm diameter fruitlets] and compared to unthinned control trees. Fruit growth was measured on individual fruit for each treatment throughout the season at weekly intervals. Thinning at FB gave a significantly lower final percentage fruit set than thinning to the same cropping level at the 20-mm fruitlet stage. However, fruit weights and soluble solids contents (SSC) were significantly higher, and the background fruit colour improved when trees were thinned at FB. The final number of fruit at harvest was less than the amount established at FB, or at the 20-mm fruitlet stage. There were significant differences between treatments in final fruit numbers per TCSA, which reflected the different crop loads. Fruit weights and SSC values were highest with the lowest crop load, and decreased with increasing crop loads. There was also a strong crop-load effect on the extent of return bloom per tree in the subsequent year. Trees thinned at FB had significantly more flower clusters than those thinned at the 20-mm fruitlet stage of. Untreated control trees had the lowest number of flower clusters. The amount of return bloom declined with increasing crop load. Second year crop loads and fruit weights were highest when trees were thinned at FB to two or four apples cm^?2 TCSA in the previous year. Trees with the highest crop load had the lowest crop load in the following year. Fruit quality was generally high for all treatments.     

两种不同肉色枇杷果实类胡萝卜素积累及合成#br# 相关基因的表达

 以‘早钟6 号’（黄肉）和‘白玉’（白肉）两类枇杷为材料,测定不同发育阶段果实果皮 和果肉中类胡萝卜素含量,并对15 个生物合成相关基因的表达进行了分析。随着果实发育成熟,β–胡 萝卜素含量在黄肉‘早钟6 号’果皮和果肉中增加,到成熟期达到最高值,分别为68.53 和11.92 μg ? g-1 FW; 在白肉的‘白玉’果皮中也呈增加趋势,到成熟期最高,为38.89 μg ? g-1 FW,但果肉中略有下降,从最 初的0.47 μg ? g-1 FW 降低至0.29 μg ? g-1 FW。两个品种果皮和果肉的β–隐黄质含量表现为持续增加,均 在成熟期达到最高值。叶黄质含量在‘早钟6 号’果皮中表现为下降,在果肉中则持续上升;在‘白玉’ 果皮中表现为先降后升,在果肉中变化不大,维持较低水平。‘早钟6 号’进入转色期后,与‘白玉’相 比,在果皮中的PSY 和CYCB 表达量较高,而在果肉中CYCB 和BCH 的表达量较高,提示枇杷不同发育 阶段类胡萝卜素的积累主要受PSY、CYCB、BCH 基因的共同调控。     

A comparison of the combined effect of water stress and crop load on fruit growth during different phenological stages in young peach trees.

Summary

The combined effect of fruit load and water stress on fruit water content and dry-matter accumulation was analysed for three phenological stages of fruit growth. Irrigation treatments were no irrigation during Stage I (NI-SI), Stage II (NI-SII), or Stage III (NI-SIII) compared with a fully irrigated control. Three thinning treatments were imposed within each irrigation treatment resulting in fruit loads ranging from low to high. Fruit harvests at the end of Stage I, II and III were used to determine total tree fruit fresh and dry matter after each stage of fruit development. Fruit water accumulation was highly sensitive to the effect of water stress at high fruit loads in all fruit developmental phases, but reductions in fruit water content were more apparent during Stages II and III than during Stage I. On the other hand, fruit dry-matter accumulation was relatively insensitive to water stress at any fruit load level and developmental stage. However, reductions in dry-matter accumulation were obtained during Stage III from those trees that were not irrigated during Stage I (NISI). Since these reductions occurred only for mid-to-high fruit load conditions, the decreases in fruit growth during Stage III appeared to be related to a carbon source limitation. The possible reasons for this source limitation are discussed.     

Developmental problems in over-winter off-season longan fruit. I: Effect of temperatures

Fruit development was investigated in the field in over-winter off-season (bloomed in late November) and on-season (bloomed in mid April) longans (Dimocarpus longan Lour. cv. Chuliang) in 2004–2005 and 2007–2008 crops, and in potted trees grown in phytotrons set at cold (15/10 °C, day/night, simulating winter) or warm temperatures (28/23 °C, day/night) in 2008. Development of fruit in both on-season and off-season longans could be divided into two stages based on the pattern of fresh weight increase. Stage I was characterized by the slow fruit growth, and Stage II by rapid fruit growth with aril expansion. Off-season longan had a longer period of fruit development than on-season longan, chiefly due to a longer Stage I. The development of off-season fruit, especially in Stage I, was exposed to low and abruptly fluctuating temperatures. In contrast, the temperatures during on-season fruit growth were warmer and less fluctuating. Off-season fruit were smaller with a significantly higher fruit drop. Intensive fruit drop did not occur during cold period until temperature had risen. Fruit cracking in off-season longan was severe (27.6%) in 2004–2005 with a dry and cold winter, but negligible in 2007–2008 with a wet and cold winter. In phytotron experiment, trees exposed to the cold temperature regime during early fruit development produced significantly smaller fruit compared to those exposed to the warm temperature regime (6.2 g vs 7.3 g), while there was no significant difference in fruit drop rate and cracking incidence. The results suggested temperatures lower than 15 °C were stressful for the growth of young fruit and reduced the growth potential and thus fruit size. Severe fruit drop in over-winter off-season longan might be associated with stressful cold plus abrupt temperature fluctuations, while severe fruit cracking in over-winter off-season longan might be related to cold and dry weather in the winter.     

Strawberry Yellows in the Variety Auchincruive Climax

Summary

Fresh ‘Mavra Markopoulou’ fig fruits, harvested close to a fully ripe state in October, were stored at ?1?C in either air or 2% O₂ (balance N₂) for 29.d. During storage in air the rates of O₂ uptake and ethylene production declined substantially and fruit weight loss increased up to 2.1%. Storage in 2% O₂ resulted in further reduction of O₂ uptake and ethylene production rates. The effects of storage conditions on ripening indices at 20?C in air were also investigated. Fruit stored in air showed decreased firmness, ethylene production rate and flesh colour lightness, but no significant or consistent changes in respiratory quotient, O₂ uptake and CO₂ production rates, soluble solids content, titratable acidity and other colour changes in peel or flesh were observed. In contrast, storage in 2% O₂ resulted in decreased respiratory quotient (although values remained above 1), O₂ uptake and CO₂ production rates and prevented fruit softening, loss of green peel colour and decrease in flesh lightness during post-storage at 20?C. All fruit were stored successfully under the above conditions, but 2% O₂ is recommended for better firmness retention during storage for longer than 8.d.     

早熟西瓜新品种‘天骄’

 ‘天骄’为早熟西瓜新品种。果实圆形，果形指数1.0，果皮浅绿底上覆墨绿色条带，单瓜质量5～6 kg，果肉大红色，肉质细脆，纤维少，中心可溶性固形物11.94%，抗裂性好，品质优良。全生育期94 d，高抗西瓜炭疽病、病毒病，中抗西瓜枯萎病，产量可达45 t·hm^-2。     

Effects of water deficit during stage II of peach fruit development and postharvest on fruit quality and ethylene production

Summary

This study examined the hypothesis that enhancement of peach quality resulting from Regulated Deficit Irrigation (RDI) is caused primarily by changes in fruit physiology during development. Water deficit was applied during either stage II of fruit development (RDI-SII) or during stage II and postharvest (RDI-SII-PH), as compared with non-droughted (control) and postharvest (RDI-PH) treatments. Fruit from the various RDI treatments had significantly higher soluble solids concentrations and red colour at harvest than control fruit. While fruit respiration was not altered by any RDI treatment, ethylene production indicated sooner the onset of climacteric phase for fruit from RDI-SII and RDI-SII-PH than for control or RDI-PH fruit. Accordingly, greater ethylene production in detached fruit was related to their having experienced water stress during development. Ethylene production by RDI-PH fruit did not change, but their quality did in terms of increased soluble solids concentration and improved skin colour similar to the RDI-SII treatment. This observation suggests that water-stress related changes occurring during fruit development are not the only factors involved in enhancing quality in RDI fruit.