Anatomy of the olive inflorescence axis at flowering and fruiting

In spite of the importance of the peduncle and pedicel in supporting and connecting flowers and fruits to the mother plant, these structures are little known in the olive, and more detailed information can be instrumental in studies of fruit development, ripening and abscission. The structure of pedicel and peduncle was studied at flowering and at fruit maturation for the Spanish olive cultivar “Picual”. Both organs have a stem-like structure. At flowering the pedicel is less developed as the transport requirements to individual flowers are minimal compared to that of the complete inflorescence, and the structure has high chances of being shed in the heavy flower abscission in this species. The peduncle is thicker, due to a ridged cortex, and has larger xylem vessel size. By fruit maturation in November, the overall diameter of both pedicel and peduncle increases, due to both conducting tissues and support tissues: in the pedicel the xylem increases 6-fold, in the peduncle 3-fold, while the phloem undergoes smaller increases. An important developmental feature of pedicel and peduncle is the increase in their capacity to mechanically support the growing fruit. To this end both organs, in addition to the increased thickness of the conducting tissues, produce a lignified sclerenchyma ring. Unlike the stem, however, which produces numerous sclereids, the sclerenchymatous ring only consists of fibres, which offer greater flexibility and make the structure less prone to breaking.     

Influence of time of harvest and maturity index on olive oil yield and quality

Harvesting plays a major role in the virgin olive oil production line, being the most expensive single component, but also due to its significant effect on the whole year's produce. Previous studies have focused on the effects of harvest timing on either oil yield or quality. Here we determined the separate and combined effects of harvesting date, fruit maturation, cultivar and fruit load on olive oil quality and quantity. Cultivars typical to the Middle East region were selected: the traditional cv. Souri and the newer cv. Barnea, grown under intensive conditions. The results demonstrate fundamental differences between the two cultivars with respect to harvest strategy. In high-yielding ‘Barnea’, oil accumulation continued throughout the ripening season resulting in increasing yield of oil with time while maintaining high quality. Hence, exploiting the production potential in ‘Barnea’ requires late harvest and advanced fruit maturity. However, in heavily loaded ‘Souri’, oil accumulation was accompanied by early massive shedding of fruits. Furthermore, late harvest and advanced maturation in ‘Souri’ were associated with a sharp increase in free fatty acids combined with a rapid decline in polyphenol content, and in MUFA to PUFA and saturated to unsaturated fatty acid ratios, all resulting in loss of oil quality. Rapid decline in oil yield coupled with deterioration of oil quality call for early harvesting at low maturity index in ‘Souri’. In medium-yielding trees of both cultivars, maturation progressed more rapidly, resulting in earlier harvest to utilize optimal oil potential.     

苹果采前落果与内源激素的关系

为了探讨苹果采前落果与内源激素之间的关系,在采前8周间定期测定了不同苹果品种的果柄、果台和离层形成部位组织中IAA、ABA含量;在采收前20d内定期测定了离层部位组织中细胞壁分解酶(Cellulase)的活性;在收获期测定了果实乙烯的发生量。结果表明:不同品种果柄、果台和离层部位组织中IAA和ABA含量变化有差异,但它们变化的总趋势相似,都是随着果实成熟IAA含量下降,而ABA含量上升;不同品种的成熟果实中乙烯发生量有很大差异,以落果多的品种显著大于落果少的品种;采前落果重的品种离层部位组织中细胞壁分解酶的活性在果实成熟期急剧增加。由于果实进入成熟阶段后,IAA含量下降,ABA含量升高,ABA/IAA之间的相对平衡被打破,高ABA/IAA以及高乙烯会刺激离层组织中细胞壁分解酶的活性增高,进而促进离层形成,这可能是导致落果发生的原因。     

Fruit set is inversely related to flower and fruit weight in olive (Olea europaea L.)

Fruit weight is strongly correlated to ovary weight in olive as big-fruited cultivars have larger ovaries and flowers at bloom. We tested the hypothesis that larger ovaries imply stronger sinks and therefore reduce fruit set, expressed as number of fruits. Flower/fruit load per centimeter of shoot was assessed every month from flowering to harvest, on sample shoots of many different olive cultivars differing in fruit size. Data were taken for two years: 2007 and 2008. Additionally, in 2008, a fruit thinning experiment was carried out by leaving a single fruit per shoot, to assess the maximum potential fruit weight achievable by each cultivar. Results indicated that fruit size was mostly genetically determined as thinned fruits of small-fruited cultivars, although bigger than control fruits, never got as big as fruits from large-fruited cultivars, confirming that large ovaries are a prerequisite for large fruits. Among all cultivars, the number of flowers per inflorescence, the number of inflorescences, and the number of flowers per centimeter of shoot were not correlated to average flower weight while total flower mass per centimeter of shoot was positively correlated to average flower weight (i.e. large flowered/fruited cultivars had greater total flower mass). However, one month after bloom and thereafter, all parameters were negatively and exponentially correlated with fruit average weight across cultivars, except fruit mass per centimeter of shoot which was generally not correlated to fruit average weight, except in one year, at harvest, when fruit mass per centimeter of shoot was positively correlated to fruit average weight. These results suggest that fruit set is a consequence of, and inversely proportional to flower/fruit size in olive.     

Removal of flowers or inflorescences affects ‘Barnea’ olive fruitlet post-anthesis abscission

A typical olive (Olea europaea L.) inflorescence consists of about 20 flowers. However, in many cultivars, only one fruit develops. This is due to massive abscission of flowers and fruitlets, which occurs during the first month after anthesis. In this study, we used the olive cultivar 'Barnea' to characterize the abscission mechanism and to try to increase fruit set by increasing the number of developed fruit per inflorescence. Removing the lateral flowers 3 weeks before anthesis increased fruit set by more than 50%. Removing all inflorescences but one from a branch increased the number of developed fruits from 0.93 to 2.8 during 2017 and from 0.91 to 3.34 fruits per inflorescence in 2018. Sugar quantification in the pistil revealed that starch level is high on the day of anthesis and low 25 days later in abscised as well as in developed fruit. Soluble carbohydrates are low on the day of anthesis, low in abscised flowers/fruitlets 25 days after anthesis and high in developed fruit. Screening the natural variation found in the Israeli germplasm collection revealed that in most cultivars less than one fruit per inflorescence has developed. However, there are unique cultivars with a higher fruit set.     

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.     

番茄花柄脱落过程中超微结构及亚细胞钙分布的变化

采用扫描电镜和焦锑酸钙沉淀的电镜细胞化学法,研究了番茄花柄脱落过程中离区细胞以及钙分布的变化。结果表明：离区的分离开始于皮层与维管束周围小细胞,先在这两个区域出现少量不连续的胞间空隙,并逐渐在维管组织区形成连续的断裂面,此后断裂面向中央的髓部组织延伸,先是维管组织的分离,然后是最中间的髓部以及最外侧表皮组织。钙分布研究发现脱落发生之前钙主要分布在细胞壁、质膜及液泡中。脱落发生后,钙颗粒主要分布在退化细胞壁和细胞间隙中,少量分布在细胞质中。皮层,维管束以及髓部细胞在整个脱落过程中钙分布以及钙形态明显不同,这可能是造成离区各组织在脱落中有不同分离程度的主要原因．     

Effect of propagation material on some quality attributes of strawberry fruit (Fragaria x ananassa, var. Selva)

In the Mediterranean region, cold-stored plants (summer planting system) are used as the main strawberry planting material (plant establishing period July–August). However, recently fresh plants (winter planting system) have also started being used for strawberry production (plant establishing period October–November). As the plantations originated from cold-stored or fresh plants differ in plant growth and yield, some differences in fruit quality have also been expected; therefore, the objective of the current study was to compare fruit quality of plants originated from different propagation material. Cold-stored plants were well developed before the beginning of the spring harvest, while fresh plants continued growth concomitantly with fruiting. The harvesting period of cold-stored plants lasted 4–6 weeks (second week of April–second half of May). Fresh plants produced fewer and larger fruits than cold-stored plants, but for a longer harvest period, which lasted throughout all summer. Differences in soluble solids and dry matter content between the fruits from cold-stored and fresh plants were observed in the first three sampling dates in both years of the experiment. In some sampling dates, significant differences in anthocyanin, titratable acidity and ascorbic acid content, were observed between fruits of plants originated from different propagation material.     

亚精胺在椪柑果实留树保鲜中的作用及其对离层形成的影响

柑橘果实越冬留树保鲜是延长果实采收期及减缓果实集中上市压力的一个有效措施,然而椪柑果实留树贮藏研究较少。本研究中以‘新生系3号’椪柑（Citrus reticulata）为对象,分析外源亚精胺（Spermidine,Spd）在果实越冬留树保鲜中减少落果的作用及可能机制。结果表明,外源喷施1 mmol · L-1 Spd明显降低了落果率,且不影响果实品质。外施Spd降低果实离层组织中活性氧含量,纤维素酶、多聚半乳糖苷醛酸酶和果胶甲酯酶等细胞壁降解关键酶活性及其基因表达量,从而抑制离层的形成。因此Spd可以用于椪柑果实留树保鲜。     

Production of fruits with attached flowers in zucchini squash is correlated with the arrest of maturation of female flowers

Summary

Results from two trials carried out under different environmental conditions indicated that the high temperatures reached in greenhouses during the Spring-Summer growing season are the main environmental factor inducing production of zucchini fruits with attached flowers. The fact that the incidence of this characteristic is genotypedependent, with the percentage of fruits with attached flowers varying from 1.4 – 73% among the different cultivars grown during the Spring-Summer season, provides an opportunity for direct counter-selection for this trait in current zucchini squash breeding programmes. High temperatures in the Spring-Summer growing season also induced male-ness in all the cultivars analysed, delaying the production of female flowers, and increasing the number of male flowers on the main stem. Indeed, those flowers that remained attached to harvested zucchini fruits were transformed into bisexual flowers, exhibiting different degrees of stamen development, and were arrested as immature, closed floral buds. A detailed analysis of the maturation and abscission times in female and male flowers of different zucchini cultivars indicated that, although abscission time did not differ, maturation time was longer in male than in female flowers. By comparing sexual expression in different cultivars in different environments, we concluded that inhibition of female flower bud maturation occurs concomitantly with a delay in flower abscission, a process accompanied by the conversion of the female bud into a bisexual bud. Given that Spring-Summer conditions promote the maturation of both female and male flowers, and that the arrest of female flower maturation and abscission are associated with floral sex determination, it is possible that the arrest of female flower maturation is not directly induced by high temperatures, but is mediated instead by hormones such as ethylene or gibberellins.     

枣离体果实水分吸收与质外体运输的研究

 为了揭示枣果吸收水分后引起的裂果机制,以‘壶瓶枣’膨大期与着色期果实为试材,分 别采用染液和清水浸泡枣果实、带叶果的木质化枣吊基部、果柄及去果柄后梗洼引入染液等处理,研究 果实水分吸收与质外体运输的途径及能力。结果表明：离体枣果实可以通过果柄、果面吸收水分,水分 经果柄木质部进入果实,后继续通过维管束或扩散作用运输到果实各个部位。膨大期青果维管束运输能 力强,着色期果实梗洼下空腔变大,果柄维管束与果实内维管束的连接发生部分中断,维管束运输能力 下降;而此时果实表皮细胞增大,排列疏松,通过果面吸水能力增大。     

Natural fruit drop and induced abscission to facilitate mechanical harvesting of Manzanillo and Souri olives

The natural drop of olive fruit, before harvest, in relation to stages of fruit development, was studied in Manzanillo olives. The absolute amount of green and half-black fruit drop was rather constant for most of the studied period. The drop of black fruit increased constantly with the advancement of maturation on both an absolute and relative basis.In studying the effect of various halogenated acetic acids on the abscission induction of Manzanillo and Souri olives, no consecutive order of activity could be found. Dichloroacetate (DCA) and monoiodoacetate (MIA) showed the highest activity. A pretreatment of Manzanillo olives with 2,4,5-chlorophenoxypropionic acid (2,4,5-TP) and chlormequat (CCC) did not affect the efficiency of various abscission-inducing chemicals.Large-scale mechanical harvesting trials with the Souri variety showed a mean increase of fruit drop up to 26% when agents such as glycerin, MIA and 2-chloroethane phosphonic acid (CEPA) were used over a period of three seasons.     

Olive seedling first-flowering position and management

The prolonged length of the juvenile period represents a substantial obstacle in olive (Olea europaea) breeding programs, delaying both the possibility for analyzing the fruit, the harvest unit, and the capacity for sexual recombination. In both olive and other fruit tree species, the juvenile–adult transition has been successfully hastened by forcing and formation procedures designed to rapidly achieve a minimum height. Precise knowledge of the position within the tree canopy where the juvenile–adult transition occurs, identified by the location of the first flowers, offers further potential for manipulating tree structure in order to hasten that transition. The occurrence of the juvenile–adult transition has been described spatially within the canopy as the formation of a juvenility cone, which we report here for olive plants from seed, and for the first time quantitatively describe its position based on the added trunk and branch distances from the soil. In canopies of seedlings from open pollination of cv. Arbequina olive the first-flowering position was consistently located, in our conditions, at an average distance of 200 cm from the trunk base. Based on that evidence, that first flowering can occur at lower positions, and on the values we obtained, three canopy-formation heights (100–130 cm, 130–160 cm and >160 cm) were compared for their effect on the length of the juvenile period and the vigour of olive seedlings. Canopy heights of 100–130 cm, much lower than the 160 cm previously reported by the olive tree breeding program of Córdoba, produced the highest number of flowering plants in the first two flowering years and also provided easier management.     

Impact of storage conditions on the apple allergen Mal?d?1

Consumption of fresh apple fruits can induce allergic reactions in humans. The apple allergen Mal?d?1 is responsible for these allergic reactions in humans in Central Europe and North America. Biosynthesis of Mal?d?1 depends on apple cultivar, and its concentration increases with time during fruit storage. However, data on the impact of different fruit storage conditions during long-term storage are scarce. Hence, the Mal?d?1 contents of eight apple cultivars were analyzed for this study during long-term storage in a cold chamber as well as under controlled atmosphere conditions (CA). After harvest, apple fruits were stored for 12, 20, 28 or 36 weeks in a cold-chamber at +?2?°C or as under controlled atmosphere conditions of 1.5?% CO₂, 1.5?% O₂ at +?2?°C. Mal?d?1 content in apple fruit of all eight cultivars examined increased during fruit storage. In most cases, differences between Mal?d?1 of apple fruits stored in the cold chamber and under CA conditions were significant, but inconsistent. In apple cv. ??Elise??, fruits stored in the cold chamber contained more Mal?d?1 compared with those stored in CA, whereas the situation reversed in other varieties like cv. ??Boskoop??. The greatest Mal?d?1 content was measured in fruits of cvs. ??Golden Delicious?? and ??Gala??, whereas the smallest Mal?d?1 level was in cvs. ??Elise?? and ??Pinova?? over the whole storage time. Overall, this experiment showed the complexity of the relationship between the Mal?d?1 content, allergenicity of apple fruits, different cultivars, storage conditions and storage time. Persons allergic to apple fruits should consume the fruits as fresh as possible or only after a limited storage time. Furthermore, they should prefer apple varieties with a low content of allergenic proteins, such as cv. ??Elise?? or cv. ??Boskoop?? as a cultivar known for its large polyphenol content.     

Fruit weight is related to ovary weight in olive (Olea europaea L.)

Fruit size is an important parameter both for scientific understanding and for commercial purposes. In many species, mature fruit size is often related to floral ovary size, but no literature exists in olive that demonstrates such a relationship. Previous work suggests that olive cultivars with different fruit sizes have similar cell number and size in the ovary transectional area, but ovary and fruit dry weight was not measured. In the present study, ovary dry weight and fruit dry weight during the whole fruit development season until harvest were measured in olive cultivars with different fruit size, over three years. Flower dry weight was also measured. Fruit weight at harvest was strongly correlated to ovary weight at bloom, both in single-year data and when data from three years were pooled. Flower dry weight, excluding the ovary, was also correlated to ovary dry weight. Ovary dry weight was strongly correlated not only to the fruit dry weight at maturity, but also at any date during fruit development. The mature fruit/ovary dry weight ratio ranged between 1000 and 4000 among cultivars, but was not correlated to the fruit dry weight at maturity. These results suggest that, in olive, fruit weight is genetically controlled through the ovary weight at bloom. This knowledge may have implications in the understanding of fruit set and source-sink relationships in olive.     

Does dry matter partitioning to fruit in early- and late-ripening peach (Prunus persica) cultivars confirm the branch autonomy theory?

Summary

We studied dry matter partitioning to fruit by establishing different patterns of fruit distribution between and within main branch units (scaffolds) on early (cv. ‘Alexandra’) and late (cv. ‘Suncrest’) maturing cultivars of peach (Prunus persica L. Batsch). The desired fruit loads were obtained by differential thinning of scaffolds and the commercial crop-load per tree was maintained. Each tree had four main scaffolds, one of these scaffolds was lightly thinned (High-crop scaffold), another one was heavily thinned (Low-crop scaffold) and the different fruit bearing stems (FBS) were alternately lightly thinned or heavily thinned in two scaffolds (Alternative-scaffold). Growth of fruits and of leafy shoots on all FBS were measured periodically from hand-thinning 30 and 50 days after full-bloom (DAFB) until harvest for cvs. ‘Alexandra’ and Suncrest, respectively. The mean fruit dry weight (DW) per FBS was strongly affected by fruit distribution between and within scaffolds in the late cv. ‘Suncrest’, indicating that branch autonomy was functional at the level of FBS in this case. In the early cv. ‘Alexandra’, mean fruit DW per FBS in each scaffold was similar, suggesting C-transfer between individual FBS. Branch autonomy could not be explained by fruit sink-strength being equal in both cultivars. In contrast to generative growth, vegetative growth was similar between scaffolds in both cultivars suggesting its independence from fruit sink removal.     

Effect of fruit size and yield on the fruit-removal-force within and between olive cultivars

The fruit-removal-force (FRF) of green mature fruit on trees of 21 olive cultivars (Olea europaea) was determined. A high positive correlation was found between fruit size and FRF, and between fruit size and the thickness of the fruit stalks. The natural FRF was not cultivar-dependent, but was determined by the mechanics of the stalk. All cultivars tested responded to ethephon. The degree of FRF reduction due to ethephon treatments was cultivar-dependent and was generally independent of fruit stalk diameter. The amount of yield per tree had no direct effect on the FRF of the fruits except via fruit size.     

Influence of harvest time and after-ripening on the seed quality of eggplant

Eggplant cv. Emi and Tsakoniki were cultivated for seed in an unheated greenhouse and fruits were harvested at 25–65 days after anthesis (DAA) in order to determine the optimum harvest time. In addition, the effect of after-ripening on seed quality (i.e. seed size and germination) was examined by storing harvested fruit at 25 °C for 20 days prior to seed extraction. From the results, it was concluded that the optimum time of harvest for seed production is 55 DAA. Seeds extracted from fruits that were harvested at 25–35 DAA did not germinate, but when fruits harvested at the same age were stored for 20 days at 25 °C prior to seed extraction (i.e. seeds were after-ripened) germination was induced. Seeds extracted from fruits harvested at 45 DAA showed a high percent germination, which decreased after storage at 25 °C for 3 months. This decrease, however, was reduced by after-ripening prior to extraction. It is concluded that although eggplant is a non-climacteric species and fruit do not ripen after harvest, nevertheless seeds within the fruit continue to fill and mature after harvest; hence storage of prematurely harvested fruit prior to seed extraction permits the seeds of these fruits to after-ripen in situ and thereby increases seed size and germination. The implication of this result for eggplant seed production is discussed.     

Phenolic content and free radical scavenging activities in rambutan during fruit maturation

The 1,1-diphenyl-2-picrylhydrazyl (DPPH^•) scavenging activity, changes and accumulation of phenolic content were studied in the peel, seed and pulp of rambutan, Nephelium lappaceum L. (Rongrien and Seeechompoo cultivars) during fruit maturation. The IC₅₀ values of the radical scavenging activity of the peels, in both cultivars remained low through fruit development (1.42–4.75 μg/mL) but the values of the seed and pulps were low at the beginning and increased markedly toward fruit development until harvest (4.87 to >1000 μg/mL). The accumulation of phenolic compounds in rambutan peels of Rongrien and Seechompoo cultivars increased continuously until reaching a maximum of 1653 and 733 mg per fruit at the time of being harvested, at 112 and 98 days after full bloom (DAFB), respectively. Ellagic acid, corilagin and geraniin in the peels of both cultivars were observed and quantified. The major component in the peels of the two cultivars was geraniin. The accumulation of ellagic acid, corilagin and geraniin in the peels increased and reached the maximum at the harvest stage, especially the major constituent of geraniin (1011 and 444 mg/fruit for Rongrien and Seechompoo, respectively). The free radical scavenging property was observed to have a relationship with the phenolic content quantified in different parts of the rambutan fruit. This research demonstrates potential data on phenolic constituents through fruit development, especially in the peels at the time of harvest.     

Differential effect of cultivar and harvest date on nectarine colour,quality and consumer acceptance

The influence of nectarine cultivar and the harvest date on fruit colour, fruit size, fruit quality parameters, and consumer acceptance were assessed. The analyses were carried on cultivars with different fruit taste (acidity and sweetness), from 5-years-old trees at the IRTA-Experimental Station of Lleida (Spain). The six cultivars were grouped in three pairs in which each had a similar commercial harvest date. Each pair comprised by a non-acid cultivar and an acid cultivar, except the pair of ‘Big Top^®’ and ‘Mesembrine^®’, which included two non-acid cultivars. The nectarines were harvested at 8 days intervals on five harvest dates, three of which were before the commercial harvest date, one at commercial harvest and another 1 week after commercial harvest.