Fruit Development Time Research Articles

Characterization, antioxidant activity, and mineral profiling of Auricularia cornea mushroom strains.

Mushrooms are considered as next-generation healthy food components. Owing to their low-fat content, high-quality proteins, dietary fiber, and rich source of nutraceuticals. They are ideally preferred in formulation of low-caloric functional foods. In this view, the breeding strategies of mushroom Auricularia cornea (A. cornea) focusing on high yield and higher quality with rich nutritional values and health benefits are still needed. A total of 50 strains of A. cornea were used to analyze the bio efficiency and the time required for fruiting body formation following the cultivation experiment. The calorimetric method was used to evaluate the antioxidant activity and quantify the crude polysaccharides and minerals content thereafter. The results showed that the time required for fruiting body formation and biological efficiency varied significantly among the selected strains. Noticeably, the wild domesticated strain Ac13 of A. cornea mushroom showed the shortest fruit development time (80 days). Similarly, the hybrid strains including Ac3 and Ac15 possessed the highest biological efficiency (82.40 and 94.84%). Hybrid strains Ac18 (15.2%) and cultivated strains Ac33 (15.6%) showed the highest content of crude polysaccharides, while cultivated strains Ac1 and Ac33, demonstrated the highest content of total polysaccharides in the fruiting body (216 mg. g-1 and 200 mg. g-1). In the case of mineral content, the highest zinc contents were observed from the cultivated strain Ac46 (486.33 mg·kg-1). The maximum iron content was detected from the hybrid strain Ac3 (788 mg·kg-1), and the wild domesticated strain Ac28 (350 mg·kg-1). The crude polysaccharides of the A. cornea strain showed significant antioxidant potential, and the ability of Ac33 and Ac24 to scavenge DPPH radicals and ABTS, which was significantly improved compared to other strains, respectively. Principal component analysis was applied to examine the agronomic traits and chemical compounds of various strains of A. cornea mushrooms. The results revealed that cultivated, wild domesticated, and hybrid strains of A. cornea exhibited distinct characteristics in terms of growth, yield, and nutritional properties. The crude polysaccharides from A. cornea mushroom strains act as natural antioxidants, the wild, hybrid, and commercial A. cornea mushroom strains can achieve rapid growth, early maturation, and high yields. The evaluation of biochemical indexes and nutritional characteristics of strains with excellent traits provided a scientific basis for initiating high-quality breeding, provided germplasm resources for the production of "functional food" with real nutritional and health value.

Inheritance of gene expression throughout fruit development in chili pepper

Gene expression is the primary molecular phenotype and can be estimated in specific organs or tissues at particular times. Here we analyzed genome-wide inheritance of gene expression in fruits of chili pepper (Capsicum annuum L.) in reciprocal crosses between a domesticated and a wild accession, estimating this parameter during fruit development. We defined a general hierarchical schema to classify gene expression inheritance which can be employed for any quantitative trait. We found that inheritance of gene expression is affected by both, the time of fruit development as well as the direction of the cross, and propose that such variations could be common in many developmental processes. We conclude that classification of inheritance patterns is important to have a better understanding of the mechanisms underlying gene expression regulation, and demonstrate that sets of genes with specific inheritance pattern at particular times of fruit development are enriched in different biological processes, molecular functions and cell components. All curated data and functions for analysis and visualization are publicly available as an R package.

Phylogenetic conservatism of fruit development time in Chinese angiosperms and the phylogenetic and climatic correlates

QuestionsDocumenting the patterns and drivers of functional trait distributions at large spatial scales is key to our fundamental understanding of the composition of plant assemblages. However, phylogeographic patterns of fruit development time (FDT, the difference between flowering and fruiting dates) have remained unstudied. Here we compiled reproductive phenology (flowering and fruiting time) and species distribution data for 6838 angiosperm species in China to explore whether FDT is more phylogenetically conserved as latitude and elevation increase, whether the phylogenetic signal of FDT correlates with phylogenetic structure and potential climatic drivers across China, and whether the environmental determinants of phylogenetic signal of FDT differ between herbaceous and woody species. LocationChina MethodsWe divided China into 268 200 × 200 km grid cells and calculated the phylogenetic signals of FDT in each grid cell using pagel’s λ. We then regressed the phylogenetic signals of FDT as a function of either latitude or elevation, individually. We examined the relationship between phylogenetic signals of FDT and climate variables using both ordinary and spatial linear regressions. We also examined the relationship between the phylogenetic signal of FDT and either net relatedness index (NRI) or clade age of each grid-cell. ResultsWe found that phylogenetic signals in FDT increased as elevation and latitude increased. The Pagel’s λ of FDT was negatively correlated with clade age but positively correlated with NRI. Precipitation in the wettest quarter was the primary variable affecting the phylogenetic signal for herbaceous species, while minimum temperature of the coldest month and temperature seasonality were the two most important climatic factors for woody species. ConclusionsStrength of phylogenetic conservatism of FDT is greater at higher latitudes and elevations. The latitudinal and elevational patterns, where mean clade age of species lowers as temperature decreases, and angiosperm assemblages tend to be more phylogenetically clustered at higher elevations and higher latitudes, could be explained by the Tropical Niche Conservatism hypothesis. The phylogenetic signals of herbs and of woody plants are triggered by different climatic drivers. Our findings have important implications for the study of large-scale geographical gradients in plant species richness, phylogenetic diversity and community assembly.

Multiple-population QTL mapping of maturity and fruit-quality traits reveals LG4 region as a breeding target in sweet cherry (Prunus avium L.)

Sweet cherry maturity date and fruit quality are relevant traits for its marketability, transport, and consumer acceptance. In this work, sweet cherry fruit development time, maturity date, and commercial fruit-quality traits (size, weight, firmness, soluble solid content, and titratable acidity) were investigated to improve the knowledge of their genetic control, and to identify alleles of breeding interest. Six sweet cherry populations segregating for these traits were used for QTL analyses. These populations descend from cross- and self-pollinations of local Spanish sweet cherries ‘Ambrunés’ and ‘Cristobalina’, and breed cultivars (‘Brooks’, ‘Lambert’, or ‘Vic’). The six populations (n = 411), previously genotyped with RosBREED Cherry 6 K SNP array, were phenotyped for 2 years. QTL analyses were conducted using a multifamily approach implemented by FlexQTL™. Fruit development time, soluble solid content, and titratable acidity QTLs are first reported in sweet cherry in this work. Significant QTLs were detected for all the traits. Eighteen were more stable as they were detected for 2 years. Of these, nine are first reported in this work. The major QTLs for fruit development time, maturity date, firmness, and soluble solid content were identified on the same narrow region of linkage group 4. These traits also showed significant positive correlation (long fruit development time associated with late maturity, high firmness, and high SSC). NAC transcription factor genes identified on this LG4 region may be candidate genes for the regulation of these traits in sweet cherry, as previously described in syntenic regions of other Rosaceae species. Haplotypes of breeding interest on this LG4 genomic region were identified and will be useful for sweet cherry breeding from this and related plant material.

COMBINED EFFECT OF DIFFERENT DOSES OF PLANT GROWTH REGULATORS (IBA AND ZEATIN) ON THE PHYSIOLOGY OF Capsicum annum L. FRUIT

Combined effect of two exogenously applied PGR i.e. IBA and Zeatin, on the fruit of Capsicum annuum L was assessed in a designed experiment. Plants were grown in pots with nine treatments and three replications. The treatments were comprised of T1-IBA 1000ppm+Zeatin 100ppm, T3-IBA 1000ppm+Zeatin 300ppm, T5-IBA 4000ppm+Zeatin 100ppm, T7-IBA 4000ppm+Zeatin 300ppm and T9-Control. T1, T3, T5, T7 were applied only at the time of floral buds emergence, whereas T2, T4, T6 and T8 were applied by dipping the floral buds during emergence and at the time of fruit development. The results showed that only T1 manifested enhance in photosynthetic pigments content i.e. chlorophyll a, chlorophyll b, total chlorophyll and carotenoids and its fruits showed Dark green colour. The physical parameters of fruit remained unaffected by PGR’s application.

Identification of Harvest Maturity Indicators for ‘Hass’ Avocado Adaptable to Field Conditions

‘Hass’ avocado (Persea americana) is a fruit in high demand in international markets, and Colombia is expanding its export to the United States. Avocado quality and shelf life are related to its harvest time. However, there is not enough information on harvest indicators in Colombia that allow producers to adequately harvest fruit to comply with market requirements. Therefore, the aim of this study was to estimate maturity indicators during two harvest periods. We harvested fruit between the years 2016 and 2017 in eight farms distributed in three regions of the Department of Antioquia, Colombia, and selected those in the postanthesis stages. We assessed variables such as fruit color, weight, dimensions, oil content (OC), and dry matter (DM). The results were analyzed using simple and multiple regressions as well as by principal component analysis (PCA). The results showed a high linear relation between DM and OC (R2 ≥ 78.88) and a significant relation between OC, rainfall, fruit development time, and environmental temperature. Nondestructive indicators that allow the establishment of DM in the field (R2 ≥ 73.57) varied according to the region and included fruit color (L*, b*), volume (P ≤ 0.05), and fruit development time. These indicators could reduce maturity heterogeneity during the harvest period.

Capsicum-Colletotrichum interaction: Identification of resistance sources and quantification of secondary metabolites in unripe and ripe fruits in response to anthracnose infection

Anthracnose, caused by Colletotrichum species complex, is one of the main fungal diseases in pepper (Capsicum spp.) crops, resulting in extensive fruit losses during pre- and post-harvesting. Plants have structural and biochemical defense mechanisms produced before and/or after the pathogen attack. Biochemical defense involve the production of compounds that accumulate at the site of infection and are toxic to the pathogen. However, the accumulation and biosynthesis of these compounds during Capsicum-Colletotrichum interaction, especially during fruit development stages remain poorly understood. In order to identify potential resistant genotypes and to improve our knowledge about the metabolites produced by pepper fruits against fungus infection, we inoculated unripe and ripe fruits of 59 accessions of Capsicum spp. with C. gloeosporioides and analyzed the disease severity during 8 days after inoculation. In this study, we observed a wide variability of fungus resistance response in unripe and ripe fruits of Capsicum spp. accessions, and ripe fruits presented greater resistance to anthracnose than unripe. Six accessions (GBUEL06, GBUEL28, GBUEL73, GBUEL87, GBUEL104 and GBUEL106) were considered as resistant for both fruits development stages and have potential to be used in future breeding programs. In addition, we selected two C. annuum accessions GBUEL103 (susceptible) and GBUEL104 (resistant), to describe the histological aspects of C. gloeosporioides infection in pepper fruits, followed by the quantification of secondary metabolites produced during this plant-pathogen interaction, using light microscopy and ultra-high performance liquid chromatography (UHPLC), respectively. The quantification of secondary metabolites produced in pepper fruits during fungus infection showed different values according genotype characteristic (susceptible or resistant), fruit development stages (unripe and ripe) and time (1st and 8th day post-inoculation). Interestingly, high concentrations of caffeic and chlorogenic acid were quantified in unripe and ripe fruits characterized as resistant genotype, showing that these biochemical compounds are putatively involved in fruit defense mechanism in response to anthracnose disease.

Phylogeny, fruit traits, and ecological correlates of fruiting phenology in a Neotropical dry forest.

In tropical dry forests, a high interspecific variation in the strategies of fruiting phenology has been documented. Therefore, phenological responses may be mediated by influence of environmental variables, functional plant attributes or phylogenetic inertia. During 2years, we recorded the fruiting phenology of 151 species belonging to 5 different growth forms of a Neotropical dry forest in Mexico. We evaluated the relationships between fruiting phenology, abiotic factors (precipitation, temperature, day-length) and functional attributes (growth form, dispersal syndrome, size and time for fruit development) using phylogenetic least squares models (PGLS). More species had ripe fruits during the dry season (92%) than during rainy months and dispersed their seeds by autochory and endozoochory. We found that fruit development time was positively correlated with fruit size and together the morphological fruit traits (size and dispersal syndrome) showed an important relationship with the growth form, but with a strong phylogenetic signal. Environmental seasonality had a strong influence on fruit ripening time, without a relevant association to the phylogeny of plant species. However, the phenological response to the environment (rainfall and day-length) at the community level was mediated by growth form. In woody species, we documented a high interspecific fruiting variation linked with the different dispersal syndromes. In herbaceous species, fruiting phenology is a trait restricted by the duration of their life cycle byrainfall seasonality, whichin turn might have selected some traits (e.g., dry fruit, presence of spines, explosive dehiscence) for maximizing seed dispersal during the dry season.

Seed mass of angiosperm woody plants better explained by life history traits than climate across China

Seed mass is a basic trait in studies of functional ecology. Examining how seed mass is affected by biotic and abiotic factors could improve our understanding of ecological strategies in plants. Here we examined the relationships of seed mass with 13 climate variables and seven life history traits, and partitioned the relative effects of life history traits vs. climate, based on seed mass data for 1265 woody angiosperm species in China. Our results showed that seed mass decreased with latitude, and most climate variables were positively correlated with seed mass. Geographic seed mass pattern was affected by both energy and water availability in the growing season, but the effect of energy availability was more important. Seed mass was also significantly related to other traits such as growth form, fruit type, dispersal mode, breeding system, leaf habit, fruit development time, and minimum juvenile period, with growth form and dispersal mode being the most closely related traits. Our results showed that climate explained much less variation in seed mass than life history traits, and that phylogeny played an important role in shaping the large-scale patterns of seed mass.

Golden bananas in the field: elevated fruit pro-vitamin A from the expression of a single banana transgene.

SummaryVitamin A deficiency remains one of the world's major public health problems despite food fortification and supplements strategies. Biofortification of staple crops with enhanced levels of pro‐vitamin A (PVA) offers a sustainable alternative strategy to both food fortification and supplementation. As a proof of concept, PVA‐biofortified transgenic Cavendish bananas were generated and field trialed in Australia with the aim of achieving a target level of 20 μg/g of dry weight (dw) β‐carotene equivalent (β‐CE) in the fruit. Expression of a Fe'i banana‐derived phytoene synthase 2a (MtPsy2a) gene resulted in the generation of lines with PVA levels exceeding the target level with one line reaching 55 μg/g dw β‐CE . Expression of the maize phytoene synthase 1 (ZmPsy1) gene, used to develop ‘Golden Rice 2’, also resulted in increased fruit PVA levels although many lines displayed undesirable phenotypes. Constitutive expression of either transgene with the maize polyubiquitin promoter increased PVA accumulation from the earliest stage of fruit development. In contrast, PVA accumulation was restricted to the late stages of fruit development when either the banana 1‐aminocyclopropane‐1‐carboxylate oxidase or the expansin 1 promoters were used to drive the same transgenes. Wild‐type plants with the longest fruit development time had also the highest fruit PVA concentrations. The results from this study suggest that early activation of the rate‐limiting enzyme in the carotenoid biosynthetic pathway and extended fruit maturation time are essential factors to achieve optimal PVA concentrations in banana fruit.

Effect of foliar treatment of sodium selenate on postharvest decay and quality of tomato fruits

Postharvest decay and quality deterioration of fruits are responsible for significant economic losses in the tomato industry. Selenium (Se) is an important microelement due to its antioxidant properties that allows detoxifying various reactive oxygen species (ROS). In the present study, the effect of a foliar treatment of Se prior to fruit development on the subsequent postharvest decay and quality of tomato fruits was investigated. Foliar treatment of 1mgL−1 sodium selenate at the time of fruit onset and development effectively controlled gray mold rot caused by Botrytis cinerea on both inoculated and naturally infected tomato fruit. Se treatment reduced lipid peroxidation, enhanced antioxidant enzyme activity of glutathione peroxidase and superoxide dismutase, and increased the concentration of non-enzymatic antioxidants, such as reduced ascorbate and reduced glutathione in the tomato fruits. Se also contributed to the maintenance of fruit quality during storage. The results suggested that Se stimulated the antioxidant defense system in tomato plants, thus making the fruits more resistant to postharvest decay caused by gray mold. Selenium treatment represents a promising strategy for managing postharvest decay and maintaining the quality of tomato fruits.

Parasites exert conflicting selection pressures to affect reproductive asynchrony of their host plant in an obligate pollination mutualism

Summary Plant reproductive phenology is generally viewed as an individual's strategy to maximize gamete exchange and propagule dispersal and is often considered largely dependent on patterns of floral initiation. Reproductive phenology, however, can be affected by proximate responses to pollinators, parasites and herbivores which could influence floral longevity or fruit development time. We examined the influence of insect interactants on within‐plant reproductive phenology in the fig–fig wasp nursery pollination mutualism in Ficus racemosa (Moraceae). Most figs support a wasp community comprised of a mutualistic pollinator, with several host‐plant‐specific non‐pollinating herbivorous gallers and parasitoids. These wasps reproduce within enclosed inflorescences called syconia, which develop into fruit after pollination. While different wasp species oviposit into syconia at varying times during its ontogeny, all wasp progeny are constrained to exit syconia simultaneously just prior to fruit ripening. Developing larvae of early‐ovipositing wasps may hasten syconium ontogeny through formation of earlier and larger nutrient sinks, whereas larvae of late‐arriving parasites may lengthen syconium ontogeny to complete their development successfully. Seeds are also important nutrient sinks. The number of seeds and the type and number of developing wasps may therefore be expected to influence syconium development times, thereby affecting the reproductive synchrony of syconia on a plant. Observations on naturally pollinated and parasitized syconia indicated that their seed and wasp content affected syconium development time. Experimental manipulations of syconia to produce only seeds or various combinations of wasps confirmed this finding. Early‐ovipositing galler progeny reduced syconium development times, while gallers ovipositing concurrently with pollinators had no effect on syconium development. Late‐ovipositing parasitoid progeny, the presence of only seeds within the syconium, or delayed pollination increased syconium development time. The differential development of syconia, which was influenced by mutualistic or parasitic progeny, accordingly contributed to within‐tree reproductive asynchrony. Synthesis. Individual reproductive units in fig trees called syconia, which also function as brood sites for pollinating and parasitic fig wasps, have plastic development durations dependent on pollination timing and species of wasps developing within them. Syconium development times are a likely compromise between conflicting demands from developing seeds and different wasp species.

PITAHAYAS: INTRODUCTION, AGROTECHNIQUES, AND BREEDING

Vine cacti of the genera Hylocereus and Selenicereus, native to the tropical regions of northern South America, Central America and Mexico, are an epiphytic group of plants bearing edible and exotic fruits. The flowers are nocturnal and remain open only for few hours. The fruits, known in Latin America as pitahaya, are sweet, juicy, and have black small crispy seeds with either a spineless (Hylocereus species) or a spiny (Selenicereus) peel. Due to the fact that pitahaya species are currently being cultivated in many countries including Mexico, Colombia, Ecuador, United States, Israel, Thailand, Malaysia, Indonesia, Japan, China, and Australia, interest in these crop species is increasing. Despite their great economic potential, vine cacti have not received much attention from researchers and little was known about these species. The first steps in introducing and domesticating these species included the development of appropriate agricultural techniques for profitable cultivation. Early studies revealed that these species are sensitive to high irradiation, extreme temperatures and saline water irrigation. Due to the self-incompatibility system of many cultivars, hand cross pollination is necessary. To ensure a continuous supply of compatible pollen for obtaining high yields, a pollen cryopreservation technique was developed. Successful reciprocal crosses were performed, and improved hybrids were obtained. Fruit development, ripening periods, and optimum harvesting time were studied for the different clones. Further intensive research and development will contribute greatly to the domestication and commercial production of these fruit crops in arid zones, where they are not yet cultivated. In addition, focused marketing efforts could lead to an even greater consumer acceptance and, hence, expanded markets. This review addresses the key findings on introduction, use, nutritional value, genetic resources, production, and on-going research programs.

An Update on Blueberry Growing in China

The early ripening date of mid-April for rabbiteye blueberries in Chengjiang signals a bright future, with a total of 338 kg of fruit harvested from 780 2-year-old plants on 0.1 ha of paddy land. In Lishui, a 0.65 ha rabbiteye blueberry orchard produced 6,000, 8,000, and 12,000 kg of fruit in the fourth, fifth, and sixth year, respectively. In 2009, in Shandong Peninsula, fruit development time was shortened by about 4 weeks because of a very late spring and sudden high summer temperature, and the fruit were difficult to separate from the peduncle and were greenish flesh. The insect pest, Sardoscelis sphenias Mayrickin, was found in mainland China for the first time.

Influence of growing conditions at different latitudes of Europe on strawberry growth performance, yield and quality

The site effect of five locations from north (Stjordal, Norway, 63 ◦ 36 � N) to south (Ancona, Italy, 43 ◦ 31 � N) was evaluated in strawberry regarding yield performance, fruit quality, length of fruit developing time from anthesis to harvest start and length of the harvest season. Cv. Elsanta was grown at all sites while cv. Korona was cultivated in north and central Europe and cv. Clery in central and south Europe. Yield was more affected by seasonal and growing conditions than by latitude. Anthesis was delayed as influenced by cultivar up to 58 days from south to north and was nearly maintained until harvest start. Duration of fruit development was negatively related to daily mean temperature and increased with higher latitude. 29-34 days were required from anthesis to harvest start for cv. Elsanta, 29-36 for cv. Korona and 27-38 for cv. Clery. Corresponding GDD values (growing degree days; 3 ◦ C base temperature) were independent from latitude and accounted to 334-355 for cv. Elsanta, 301-385 for cv. Korona and 320-434 for cv. Clery. Daily mean temperature decreased about 2 ◦ C from south to north during anthesis to harvest start which induced a calculated 5.2 days longer fruit development period in the north. From harvest start to harvest end, GDD values varied for all cultivars between 297-402 GDD showing no influence of the latitude. However, simple summing of GDD values do not correctly describe the time of fruit development (from anthesis to the ripe fruit) for the whole fruiting period of a plant. GDDs for individually tagged flowers increased notably from the first third to the last third of the developing period due to increasing temperature as the season proceeded. The fruit quality standards dry matter, soluble solids and titratable acidity were influenced by latitude giving northern sites in general the highest values. Fruits grown at the southern sites were redder compared to those of the north.

Herbivore-induced changes in fruit-frugivore interactions

Summary 1. Herbivore attack can induce dramatic changes in plant chemical defences. These responses protect plants against future herbivory, but can also have important physiological and ecological costs. Ecological costs of defence have received recent theoretical attention; however, many proposed costs have not yet been demonstrated empirically. In particular, field data are lacking as to whether induced responses in leaves can lead to correlated changes in fruit palatability that reduce fruit removal by mutualist seed dispersers. 2. Using the tropical shrub, Hamelia patens (Rubiaceae), we examined changes in fruit removal, palatability and maturation time following various treatments to the subtending leaves, including herbivory, mechanical damage and/or application of methyl jasmonate (MeJA). 3. Fewer fruits were removed from herbivory- and MeJA-treated branches than from controls, and results from three bioassays with ants and fungi suggested that this response was mediated by changes in fruit palatability. In addition, fruits from MeJA-treated branches matured more quickly than those from control branches. 4. Synthesis. Taken together, our results provide novel evidence that induced responses to herbivory can affect fruit–frugivore interactions through two mechanisms: changes in fruit palatability and changes in fruit development time. This highlights the importance of physiological linkages between leaf and fruit traits in determining the overall costs of plant defence and the fitness outcomes of multispecies interactions.

Adaptability of Pecan as a Species

Pecan [Carya illinoinensis (Wangenh.) C. Koch] is indigenous to the Mississippi River drainage system of the United States. Climate in the native pecan region ranges from humid to semiarid and from mild to harsh winters. Rainfall is bimodal with peaks in March to April and in August to September. Pecan is site specific and is the climax tree species on loamy, well drained, first bottom river land with a relatively high water table. Detrimental effects from pecan's shade intolerance from its more vigorous, sympatric species are minimized as these species are specific to differ sites. Pecan's deep and phreatophytic rooting habit ensures soil moisture during drought periods and facilitates pecan's survival in semiarid regions. Root development in the humus-surface layer ensures nutrient uptake from the most nutrient rich layer of the soil and, when the lower soil profile is saturated, aeration for the roots and water and nutrient uptake. The bimodal rain pattern replenishes soil profile moisture and its timing ensures seed germination, stand establishment, well-developed seed, and minimal drought stress. Natural selection for freeze tolerance and for minimum fruit development time allows survival in areas with harsh winters and short growing seasons. Regulation of seed germination and budbreak by heating and chilling results in pecan being native in cold and warm climates, greatly increasing the native range. The northern limit for pecan is dictated by heat units; the southern limit is restricted by lack of bimodal rains and vivipary. Reproductive stress is caused by the high lipid content of seed, but is counteracted by a long juvenile growth period of the seedling, by a small nut size and low percentage kernel, and by “off” production years of the tree. Nut and percentage kernel decrease as the growing season decreases which contributes to species survival in geographical regions with a short growing season. Selection for small nuts with low percentage kernel is enhanced by predators. Tree reserves are depleted by heavy production during “on” years and are replenished during “off”years. Perpetuation of pecan forests is apparently from sib/half sib seedlings following predator satiation while dissemination into new areas may be mainly by predators. Pecan and its pests successfully co-exist. Major defense against fruit feeders is escape in time, leaf feeders by biological associations and accommodation, and leaf diseases by confrontation. Heterozygous progenies from cross-pollination provide ample genetic diversity for continuous pecan selection to endure pressures imposed throughout a wide climatic range. Ecological adaptions within native pecan forests should be used in developing and maintaining commercial pecan orchards.

INSIGHT INTO ALTERNATE BEARING OF PECAN

The fundamental cause of alternate bearing in pecan [Carya illinoinensis (Wangenh.) K. Koch] is unknown, but is closely linked to the size of the dormant season carbohydrate pool. Nut yields (over a period of up to 78 years) were evaluated, for 66 cultivars, in regards to alternate bearing intensity (I). Best-fit regression analysis indicates no association between I and fruit ripening date (FRD) or nut volume; although, there was moderate association with post-ripening foliation periods (PRFP) in that I tends to decrease as the length of the PRFP decreases. Multiple regression models indicated that FRD and nut volume were poor predictors of I, however PRFP possessed significant inverse predictive power. Late-season canopy health, as measured by percentage of leaflet retention, decreased as FRD approached early-season ripening. Late-season photoassimilation rate was higher on foliage of trees with late FRDs than those with mid- or early-season ripening dates. Sprays of either Alar or ProGibb to the canopy of either “On” or “Off” trees altered return bloom the following year. These data provide new insight into the complex nature of alternate bearing in pecan and are interpreted to indicate that alternate bearing in pecan is regulated by; a) gibberellins during the time of fruit development, and b) the size of the carbohydrate pool at about the time of bud break.

Characteristics of vertebrate-dispersed fruits in Hong Kong

ABSTRACTHong Kong has a native angiosperm flora of approximately 1800 species, of which 27% (482 spp.) bear fleshy, presumably vertebrate-dispersed fruits, including 76% of the 337 tree and shrub species and 70% of the 103 climber species. Morphological characteristics were determined for 255 species and nutritional characteristics of the fruit pulp for 153 species. Most fruit species were black (45.1%) or red (24.3%) and 85.9% had a mean diameter <13 mm. Nutritional characteristics varied widely between species with ranges and median values as follows: pulp percentage (range 10.0–99.2%, median 69.2%), water content of pulp (11.1–94.0%, 78%), lipid (0–84.0%, 2.0%), soluble carbohydrate (4–88%, 53%), nitrogen (0.2–3.4%, 0.86%), neutral detergent fibre (1–44%, 14.3%). Fruit development time (50–360 d, 156 d) showed a negative correlation with lipid content, but no significant correlation with fruit or seed size. Principal components analysis of fruit characteristics was dominated by a trend from single-seeded fruits with a thin, lipid-rich pulp layer to multiple-seeded fruits with much, watery, carbohydrate-rich pulp. Birddispersed species cover the full range of fruit characteristics except those too large to swallow and too hard to peck bits from. Mammals (bats, civets and/or macaques) are known or suspected to consume most of the fruits too large for birds as well as many bird fruits but none with high-lipid content. Summer fruits (May—September) were significantly larger and had significantly higher seed size and carbohydrate content than winter fruits (November-March). Winter fruits took more than twice as long to develop as summer fruits.

Influence of air and soil temperatures on grafted and self-rooted Passiflora hybrids

When passionfruit were grown in a glasshouse under semi-controlled conditions, high air and soil temperatures (25°C) increased leaf area (LA), leaf number (LN) and shoot length (SL). Grafting also increased these parameters, particularly under low air and soil temperatures (18°C). An air temperature of 18°C increased flower numbers per vine; 18°C air and 25°C soil temperature yielded the highest fruit set. A soil temperature of 25°C also increased fresh fruit weight and seed number. Grafted plants yielded the highest fruit dry matter under 18°C air and 25°C soil temperature. Both 25°C treatments shortened fruit development time.