Developmental problems in over-winter off-season longan fruit. II: Development of pericarp structure

Fruit development was investigated in field and changes in pericarp structure were comparatively studied in over-winter off-season and on-season longan (Dimocarpus longan Lour. cv. Chuliang). The results showed developmental problems including small fruit size, severe fruit cracking and heavy fruit drop in the off-season fruit, although their seed size was not significantly affected compared to the on-season fruit. Anatomical studies showed that off-season longan fruit had a poorly developed pericarp, which was reflected by smaller fresh weight as well as thinner pericarp thickness, thinner spongy tissue, fewer cell layers in the periderm, smaller cell size and fewer cell numbers in the parenchyma tissue at the upper mesocarp, and fewer cell layers in the endocarp. In contrast, the recovery of the sclereids in the mesocarp was higher in the pericarp of the off-season fruit. The poor development of the pericarp in off-season fruit probably caused the small fruit size and severe fruit cracking. It was suggested that the adverse climatic conditions encountered by fruit development in the over-winter off-season longan suppressed cell division and expansion in the pericarp but did not affect sclereid formation.     

Cultivar-based fruit size in olive depends on different tissue and cellular processes throughout growth

In drupe fruits, in addition to fruit size, the proportions of mesocarp and endocarp tissues are critical objectives for fruit quality, crop production and management. The olive fruit is a typical drupe, with cultivars which show a wide range in both fruit size and the proportions of mesocarp and endocarp. Characterizing the roles of tissue and cellular processes in producing genetically based fruit size variability is necessary for crop improvement, as well as deepening our understanding of fruit developmental physiology. This study used microscope image analysis to evaluate cell number and size, the growth of mesocarp and endocarp tissues, and their developmental timing in producing fruit size among six olive cultivars with a large range of fruit size. We found that cultivar mesocarp and endocarp size increased linearly with fruit size, with larger sizes favoring an increasingly greater mesocarp/endocarp ratio. Within the mesocarp, cultivar-based fruit size related directly to cell number and was established soon after bloom by cell division rate. In spite of different cell division rates, all cultivars showed similar timing of cell division activity, with the majority of cells produced in the two months after bloom but, surprisingly, a substantial number of cells formed during the following 6 months. Cell expansion was high throughout fruit growth and an important factor in achieving final fruit size, but cell size did not differ among cultivars at any time. We can conclude that fruit size differences among olive cultivars are due at the tissue level to both mesocarp and endocarp sizes and at the cellular level to cell division throughout fruit growth. Furthermore, since cell size is consistent among cultivars in spite of variable cell division, it is likely that cultivar differences in cell expansion accompany those in cell division.     

加工番茄果面喷施CaCl2和NaCl对果皮显微结构的影响

以加工番茄品种‘里格尔87-5’和‘石红12’为材料,研究了果实发育期果（叶）面喷施低、中、高浓度NaCl（3.0、6.0和9.0 g·L^-1）和CaCl₂（2.0、4.0和8.0 g·L^-1）对果皮显微结构的影响。结果表明：对‘里格尔87-5’品种,中浓度CaCl₂处理使外果皮细胞层数显著增加,不同浓度CaCl₂和低浓度NaCl处理均不同程度地延缓细胞间隙的增大,低、中浓度NaCl和CaCl₂处理使外果皮厚度和外果皮外侧细胞壁厚度增加;对‘石红12’品种,高浓度CaCl₂理使外果皮细胞层数显著增加,中浓度CaCl₂处理使外果皮外侧细胞壁厚度增加,并延缓细胞间隙的增大,低浓度NaCl处理亦能延缓细胞间隙的增大,低、中浓度NaCl和CaCl₂处理使外果皮厚度增加,高浓度NaCl处理显著减小外果皮外侧细胞壁厚度,但增加中果皮维管束数量。综合分析认为,在果实发育期间果（叶）面喷施低、中浓度的NaCl和CaCl₂可以改善加工番茄果皮结构,有利于提高采后果实的耐贮运性。     

温州蜜柑粗皮大果形成过程的解剖学研究

【目的】为了明确温州蜜柑粗皮大果形成的原因和关键时期,【方法】试验以‘国庆一号’温州蜜柑为材料,比较果实发育过程中,粗皮大果与薄皮果果蒂处果皮的显微结构差异。【结果】结果表明,花后21 d粗皮大果中果皮细胞开始排列疏松,花后28 d其外果皮出现凹凸不平现象,这些均与薄皮果存在明显差异;花后7～21 d果皮细胞层数快速增长,导致果皮增厚,粗皮大果与薄皮果表现显著差异;果实成熟前,薄皮果果皮逐渐变薄,粗皮大果的果皮却不断增厚,成熟时其果皮厚度达到薄皮果的3.8倍。【结论】花后7～28 d是粗皮大果果皮增厚的关键时期。     

龙眼果皮发育解剖学观察

以储良龙眼品种为试材,观察了果皮的解剖结构发育特点。果皮发育早期(花后10d前),细胞体积小,排列紧密,细胞分裂活跃,外果皮有凸起的皱褶结构,有大量的表皮毛分化。果皮发育中期(花后10～52d),细胞体积变大,表皮毛开始脱落,外果皮逐渐平滑,中果皮处有石细胞群和海绵状组织的分化。果实发育后期(花后52d后,假种皮快速膨大阶段),有木栓形成层出现,形成周皮代替表皮起保护作用,随着果实生长,木栓层出现局部破裂。龙眼果皮可划分为外、中、内3层。中外果皮在发生次生木栓化前,由外表皮细胞及其附属物和角质层组成;在形成木栓形成层产生次生结构后,外果皮则由周皮组成。内果皮来源于子房内壁的几层细胞,由一层内表皮细胞和与之紧密相连的几层薄壁细胞组成。中果皮根据其组织特点可进一步分为上中果皮和下中果皮,上中果皮包括石细胞群、外层维管束和外果皮之内的薄壁细胞;下中果皮则主要包括海绵组织和其中的维管束。     

荔枝果皮发育细胞学研究

 以‘淮枝’荔枝为试材, 对花前子房和花后果皮发育的解剖学特点进行了观察。荔枝果皮可划分为内、中、外3 层, 外果皮由单层表皮细胞、龟裂片峰处表皮细胞上的角质、裂纹处表皮细胞上的薄壁细胞构成; 中果皮是构建果皮的主体, 由龟裂片峰下的厚壁组织、上中果皮和下中果皮构成; 内果皮由薄壁未木栓化的皮层细胞构成。果皮的细胞分裂主要发生在开花前, 花后不同部位的果皮细胞还有一定的分裂行为, 但分裂的旺盛程度和停止时间有所不同, 下中果皮停止早, 约在花后19 d , 上中果皮其次, 约在花后32 d , 内果皮和裂纹处外果皮最晚, 约在花后47 d。细胞膨大规律总体呈“慢- 快- 慢”的S 型。     

Involvement of cell proliferation and cell enlargement in increasing the fruit size of Malus species

Cell number and cell size in the fruit flesh of five Malus cultivars (two crabapples and three domesticated apples) were analyzed from soon after blossom until maturity. M. floribunda, whose fruit size is one of the smallest among Malus, exhibited absence of cell proliferation throughout fruit ontogeny. Furthermore, the rate of cell enlargement, which was almost uniform until the mature stage in other species, slowed down from about 45 days after full blossom (DAFB), resulting in a cell size approximately half that of the other cultivars. The fruit of M. coronaria, which is of medium size, possessed approximately half the cell number of M. domestica cv. ‘Fuji’, due to a slower proliferation rate. The cv. ‘Sekaiichi’ of M. domestica had the largest fruit among the cultivars investigated, and showed a faster increase in cell number. These results indicate that a combination of greater cell division capacity and an enhanced degree of cell enlargement are involved in the increase of Malus fruit size.     

大果型和小果型荔枝品种果实发育细胞学和生理学比较

以大果型鹅蛋荔和小果型淮枝品种为对比试材,研究结果表明,两者果实干重、鲜重均相差2.6倍以上;鹅蛋荔大于淮枝既有库大小的原因,也与库活性大小有关;库大小主要体现在细胞数量上而与细胞大小无关;在果实发育期间,大果型的鹅蛋荔果皮中ZRs含量和ZRs/ABA一直高于小果型的淮枝;鹅蛋荔果实的呼吸率高于淮枝。     

The addition of gibberellic acid to auxin solutions increases sugar accumulation and sink strength in developing auxin-induced parthenocarpic tomato fruits

The effects of the addition of gibberellic acid (GA) to auxin solutions for tomato fruit setting on sugar content and titratable acidity at maturity were investigated in ‘Louis 60’ tomatoes, and sucrolytic enzyme activities and cell development during the early stages of fruit development were examined to explain the physiological mechanisms. Days to maturity and titratable acidity were not affected by GA addition. The sugar concentration of the pericarp was increased by 50 mg L⁻¹ of GA addition in the summer and the spring, but not in the autumn experiment. The product of sugar concentration and fruit weight, which is thought to reflect the amount of sugar per fruit, was higher in GA-treated fruit in every experiment. Beginning 1 day after treatment, cell size was larger in GA-treated fruit and resulted in an increase in pericarp thickness at maturity. These results suggest that GA addition at anthesis can promote an increased sink size of individual pericarp cells immediately after treatment. The activities of VAI and neutral invertase (NI) were higher in GA-treated fruit around 5 days after treatment, and the possibility of VAI and/or NI involvement in sink activity at an early stage of fruit development is suggested.     

Physiological disorders of the apple at mid-season stage of development

Morphological and anatomical development of epidermis, hypodermis and cortical cells in relation to cuticle on young developing apples were observed by scanning electron microscopy (SEM). Initial symptoms of abnormal cell development appeared in the orchard at approximately mid-season growth as depressions on the fruit surface. They were observed on the calyx or basin areas, light-reddish brown in color with a light-greenish margin. Normal fruit tissue was covered by a well-defined, uniform cuticle subtended by an epidermis contiguous to 10–12 layers of hypodermal cells. In areas where anthocyanin development was evident, collapse and fragmentation of cortical cells extended deep within the cortex nearly to the core-line bundles. The cuticle was thin, subtended by fragmented thick-walled hypodermal cells; however, cuticle thickening occurred at the edge of the tissue fissure. Cell senescence was indicated by extreme cell-wall thickening in the hypodermis. The fruit was incapable of further growth expansion in the affected area, as a result of cell collapse.     

疏花对大久保桃中果皮细胞分裂与膨大的影响

 研究了大久保桃树〔Prunus persica (L. ) Batsch. ‘Okubo’〕疏花后果实生长发育期间果皮细胞分裂与膨大的变化。结果表明: 果皮细胞分裂一直持续到盛花后6周。疏花明显促进了花后3周内幼果中果皮的细胞分裂, 增加了果实中果皮细胞层数和果皮厚度, 这是导致成熟果实体积增大的主要原因。     

Early growth and development of the olive fruit mesocarp

SUMMARY

We examined growth and development of the ‘Manzanilla’ olive fruit mesocarp in transverse equatorial sections during the first 12 weeks after full bloom (AFB). Sequential sampling and quantitative data provided an integrated view of the formation of this tissue. The mesocarp, or fruit flesh, was formed by relatively isodiametric parenchyma cells with a small number of isolated sclereids. By four weeks AFB a gradient in cell size characteristic of mature olive fruits began to appear. Biweekly measurements of cell size and number indicated that, as in other drupes, both cell division and expansion contribute to initial mesocarp growth. From six weeks AFB, further mesocarp growth was determined solely by cell expansion. Transverse areas of mesocarp and endocarp, also measured biweekly, revealed that both tissues expand in a similar manner until eight weeks AFB, after which mesocarp growth predominated.     

Analysis of effects of auxin on fruit size of tetraploid and diploid tomato fruits

Selfed and auxin-treated fruits of tomato (Lycopersicon esculentum Mill.) were obtained from tetraploid and diploid plants and compared to determine why selfed tetraploid fruits are smaller. Application of auxin to ovaries produced tetraploid fruits as large as normally set (selfed) diploid fruits but led to reduced fruit size in diploid fruits, reflecting a further potential for tetraploid fruit development. The selfed tetraploid fruits were found to be smaller because they had fewer cells per fruit. Cell size (diameter) at the end of fruit development was similar for all fruit types. DNA per cell did not closely match cell size during development, especially during the cell division stage. Protein per cell also failed to follow cell size. Protein per DNA showed one peak at around day 10 of fruit development and possibly a second one at day 30.     

Salinity effects on the network of vascular bundles during tomato fruit development

The development and distribution of the conducting tissue of tomato fruit in relation to salinity was studied by recording the number of vascular bundles in different layers of the fruit tissues at different growth stages in fruit grown at three levels of salinity (electrical conductivity, 5,10 and 15 mS cm'1). The uptake of safranin through the pedicel was used to locate the lignified xylem tissue in the bundles. Pericarp and placenta were supplied by separated vascular networks. Both the number and the density of vascular bundles (per cross sectional area of fruit tissue) were higher in pericarp than in placenta. The number of bundles decreased from the proximal (pedicel) half to the distal (blossom-end) half of the fruit, more so in the placenta than in the pericarp. The average density of bundles decreased from 1.7 and 0.6 bundles mm-2 in pericarp and placenta, respectively, to less than 0.1 bundles mm'2 during fruit expansion from dl4 to d31. The average density of bundles in layer 5 of the placenta was 2.5 times lower than that of the pericarp throughout fruit development. Salinity reduced the number of both total and stained bundles especially in the distal layer of the placenta. Therefore, xylem tissue development in the distal fruit tissue was substantially retarded at high salinity and this may be the anatomical basis for the initial Ca deficiency symptom of blossom-end rot in the distal placenta.     

Improving ‘Bing’ sweet cherry fruit quality with plant growth regulators

Final fruit diameter is the prime determinant of sweet cherry fruit value. Previous research has shown that mesocarp cell size accounts predominantly for variability in final fruit size, within a genotype. Our research program evaluated the potential to improve sweet cherry fruit size/weight with growth regulators to affect cell division and/or cell expansion stages. In the current study we screened 8 plant growth regulators (PGRs), including cytokinins, gibberellins, and auxins, and their combinations for their ability to increase ‘Bing’ fruit weight. Each PGR was mixed in lanolin paste and applied to fruit pedicels at 9 or 30 days after full bloom (DAFB), to coincide with estimated peak in cell division and cell expansion activity, respectively. Several cytokinins applied 30 DAFB improved fruit weight significantly (ca. +15%) with N-(2-Chloro-4-pyridyl)-N′-phenylurea (CPPU) and 6-(3-hydroxybenzylamino) purine (mt-Topolin) at 100 mg l⁻¹ being the most effective. Gibberellins, applied alone, improved fruit size and delayed fruit maturation and exocarp coloration. GA₃ at 200 mg l⁻¹ applied at 9 DAFB was the most effective and improved final fruit weight by 15%. Fifty-six percent of the fruit from this treatment were ≥9 g compared to 15% of similar weight fruit from untreated limbs. Both GA₃ and GA_4/7 treatments applied 9 DAFB increased fruit radial expansion. 4-Chlorophenoxyacetic acid, a synthetic auxin, also stimulated higher fruit growth rates at stage I and stage II, and fruit color development, but did not improve final fruit size.     

47份无患子种质果实性状与种子性状的相关性研究

本研究对收集的47份无患子种质的果实数量指标包括单果重、果纵径、果横径、果侧径、果皮厚、果皮重、果实体积以及果实中种子性状数量性状指标包括种纵径、种横径、种侧径、种子重、种子体积进行了测量.结果表明,无患子种子性状与果实各性状指标间均呈线性正相关.各性状中单果重差异最显著,最大10.11 g,最小2.78 9;47份无患子果实的表型性状变异程度：果皮重＞果皮厚＞果实体积＞种子重＞种子体积＞种侧径＞果横径＞果纵径＞果侧径＞种横径＞种纵径;对无患子不同种质间果实性状进行聚类分析,结果表明无患子依果实体积大小聚类.     

西瓜新品种苏创3号的选育

苏创3号是以G21为母本、W13为父本配制而成的早熟优质西瓜一代杂种,植株生长势较强,全生育期109 d(天)左右,果实发育期33 d(天)。易坐果,果实圆形,果皮绿色,覆深绿色细齿条带;瓜瓤红色,瓤质酥脆,纤维少,中心糖含量11.9%,边糖8.8%;果皮厚约0.95 cm,单瓜质量4.3 kg,每667 m~2产量2 850 kg左右。适宜江苏生态相近地区保护地栽培。     

南果梨果实外观品质的形成

以48年生南果梨树为试材,研究了南果梨果实外观品质的形成过程。结果表明,南果梨果实的生长动态曲线呈S型,而且果实在整个生长期内都在膨大,适当晚采有利于果实增大;叶绿素和类胡萝卜素的变化趋势相似,在6月12日有一个小的高峰,但花青素的形成有两个明显的高峰分别出现在果实生长的中期和成熟期;果皮细胞层数在5月14日达到最大层数后开始减少;果点大小的生长动态和果实生长动态相似,基本呈S型,并随果实的增大而增大;果点密度随果实的增大而变小,但6月19日前迅速减小,之后缓慢减小;果皮厚度一直呈增加的趋势,但其中有一个下降期。     

The Effects of Fruit Thinning on the Development of Cox’s Orange Pippin Apples in Relation to the Incidence of Storage Disorders

Severe hand thinning of fruitlets on Cox’s Orange Pippin trees five weeks after full blossom led to a doubling of fruit weight by harvest. Although the rate of cell division was stimulated slightly, the larger fruit size was due mainly to an increased rate of cell enlargement.

The respiration rate of whole fruits was slightly higher after thinning and the onset of the climacteric rise was advanced. Respiration per cell was correspondingly higher in the larger cells of the thinned fruit and respiration per unit protein was similar to that of fruit from unthinned trees.

Potassium, magnesium, and phosphorus contents, expressed on a fresh weight basis, were higher in the cortical tissue of the thinned fruits. Calcium per unit fresh weight was unaffected by thinning and the ratio of calcium to cell surface remained relatively constant throughout development in both types of fruit.

Senescent breakdown and bitter pit developed during storage only in the thinned fruit. Slight differences in the incidence of rotting and low temperature breakdown between the two types of fruit are attributed to the effects of maturity rather than of fruit size.