Manual harvesting of fruits is an expensive, time-consuming, and labor-intensive operation. Due to labor shortages in the late 1950s, mechanical harvesters were developed to reduce the need for labor and to reduce cost. The most common mechanical harvesters are limb, trunk, and canopy shakers. Catch frames are used during mechanical harvesting to collect fruits and reduce fruit damage. Efficient fruit harvesting without tree damage requires selecting the appropriate harvesting technology based on: (1) tree characteristics – type, size, natural frequency, damping properties, and the architecture of the tree; (2) fruit properties – shape, size, stem length, and maturity level; and (3) vibration techniques – shaker type, mass, amplitude, excitation frequency, and clamp position. Although mechanical harvesting increases harvest efficiency, it has disadvantages, which can include (a) tree injury, (b) fruit damage, (c) debris and trash, (d) the need for specific orchard design and tree training, (e) significant capital investment, and (f) machine maintenance costs. Recent advancements in sensing and machine vision techniques have significantly improved automation in new mechanical harvesters, and increased the efficiency and productivity of new harvesting machines. Growers can benefit from smart harvesters that are less operator-dependent. In addition, because harvesters are expensive and not used for more than two months a year, much tree crop harvesting is contracted with commercial services, making harvest time an important parameter. This review discusses the current mechanical harvesting technologies for some selected temperate and tropical nut and fruit trees, the factors affecting mechanical harvesting, smart harvesting techniques and challenges, and provides an overview of mechanical harvesting and its future outlook.
Banana is one of the leading crops in world fruit production and world trade. It is grown globally in subtropical and tropical regions, and can be served for fresh consumption or used as a staple food in many countries. Postharvest physiological disorders are a major threat to the banana fruit industry and can cause significant economic losses worldwide. Such disorders include finger drop, senescent spotting, and chilling injury. These are common disorders of banana which are associated with more than one factor, such as environmental conditions in conjunction with genetic factors, but some disorders mainly occur due to only one factor. There is a need, therefore, to understand the basic causes behind a particular disorder and how it can be overcome with appropriate management practices. This review not only describes the causes of such postharvest physiological disorders of banana, but also discusses the biochemical processes involved in their development. Practical management methods that can be used to prevent the disorders and to retain fruit quality for high value markets are presented.
Oakleaf hydrangea is a shrub that is native to the southeastern United States and is growing in popularity as an ornamental plant. Like other cultivated hydrangea species, oakleaf hydrangea has showy flowers but also has unique phenotypic characteristics that provide additional value as an ornamental shrub. Despite the enormous popularity of hydrangeas as garden plants, little research has been done on oakleaf hydrangea. This review synthesizes the existing oakleaf hydrangea literature and draws on work done in other Hydrangea species to bring attention to the current knowledge and identify gaps to be filled. After introducing the genus, the review focuses on the horticultural aspects of oakleaf hydrangea, genetics and breeding of several selected traits, as well as the conservation concerns for the species. Finally, future lines of research that would provide valuable information for the breeding and conservation of oakleaf hydrangea are suggested.
Apple crop load management and related fruitlet abscission have been major research priorities for the last century in pomology. From these efforts, two main models were developed to explain the mechanisms leading to fruitlet abscission: correlatively driven abscission proposed by Bangerth; and carbohydrate stress initially proposed by Botton et al. Both models agree on the final step leading to differentiation of the abscission zone, specifically decreased polar auxin transport through the abscission zone, causing it to become sensitive to ethylene. However, these models propose different abscission induction mechanisms. Correlatively driven abscission proposes that polar auxin transport of fruitlets within a spur meet at "autoinhibitory junctions" in the peduncle, where polar auxin transport from dominant fruitlets can reduce that from inhibited fruitlets. The carbohydrate stress model proposes that polar auxin transport ceases because of embryo death in the seed following an increase in ethylene biosynthesis in the cortex due to chemically- or naturally-induced oxidative stress from limited carbohydrate availability. We provide an overview of the studies that led to these models and analyze their validity in the context of physiological factors that have been shown to affect apple fruit abscission, including chemical thinner mode of action, and king dominance.
Chapter 2 Biostimulants in Agricultural and Horticultural Production Jessica C. Bell, Jessica C. Bell Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, AustraliaSearch for more papers by this authorSally A. Bound, Sally A. Bound Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, AustraliaSearch for more papers by this authorMichele Buntain, Michele Buntain Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, AustraliaSearch for more papers by this author Jessica C. Bell, Jessica C. Bell Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, AustraliaSearch for more papers by this authorSally A. Bound, Sally A. Bound Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, AustraliaSearch for more papers by this authorMichele Buntain, Michele Buntain Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania, AustraliaSearch for more papers by this author Book Editor(s):Ian Warrington, Ian Warrington Massey University, New ZealandSearch for more papers by this author First published: 04 November 2021 https://doi.org/10.1002/9781119851981.ch2 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary Plant biostimulants offer promising opportunities to aid in addressing the challenges faced by contemporary agriculture – maintaining viable yields of high-quality produce while reducing the environmental footprint of production. Biostimulants have been shown to enhance plant growth, boost yields, and increase crop tolerance to abiotic stress, acting via a number of mechanisms including phytostimulation, biofertilization, and biocontrol. In the European Union, frameworks and industry standards that require rigorous scientific evidence for all claims have been introduced as a requirement for product registration. However, a lack of regulation in many countries, including Australia, has led to significant variation in product quality and inconsistent results in the field, issues that remain to be addressed. As industry develops the next generation of biostimulant products, the potential for synergistic effects when applying different categories of biostimulants in combination has generated particular interest. In the realm of microbial inoculants, the formulation of microbial consortia which look to harness the beneficial action of multiple species is being investigated. The potential for biostimulants to add value to soilless production systems is another area for development in this space. As biostimulants encompass a diverse group of products, this review focuses on three categories: microbial inoculants, humic substances, and seaweed extracts. After summarising the current understanding of how these substances operate, as well as the crop responses they have been shown to elicit, we examine the challenges facing the development of more effective and reliable products and explore some of the key areas for future research. Horticultural Reviews, Volume 49 RelatedInformation
Durian is native to Southeast Asia where it is grown commercially. It is also a common feature of home gardens in rural areas. The durian has been introduced to other tropical countries where limited commercial production occurs, although it is commonly found in arboretums. It is known for its unique intense aroma and its sweet custard-like aril flesh, which have led to its title of “King of Fruit.” It has ardent afficionados who strongly advocate the appeal and benefits of the fruit. The aril flesh contains a number of different bioactive compounds, many of which are beneficial to human health. Processed durian products are available worldwide and are in demand by consumers. A short period of water stress induces flowering and, though there are some differences amongst cultivars, this stress requirement leads to periods when there is an excess fruit available in markets. This climacteric fruit has a short postharvest life at ambient temperatures that has posed problems in extending the marketing period, and this is compounded by its strong and particular smell that makes it difficult to export to distant markets. Research is needed to develop improved cultivars that have both disease and insect resistance, to develop production practices that control flowering and enhance yield and fruit quality, and to extend knowledge of postharvest physiology and technology to improve handling and to extend the fresh market period within the postharvest chain.
Plants possess a remarkable acclimatization capacity at (sub)cellular level that enables them to tolerate unfavourable growing conditions to a greater extent than that possible without such changes. These specialized plant cells can sense mechanical forces or deformation, brought about by environmental cues or crop management practices, and convert these physical impacts into specific response mechanisms. This review describes some possible physiological and molecular mechanisms that are responsible for sensing and transducing mechanical signals by living cells. Mechanical stimuli are perceived at the cytoskeleton–plasma membrane–cell wall interface that subsequently triggers ion channel activity, ion- (e.g., Ca2+) mediated signaling responses, followed by downstream signaling events such gene expression and protein and metabolite (e.g., plant hormones) adjustment. In turn, a progressive acclimation and morphological change at the tissue and whole plant level takes place in response to mechanoperception. The potential of mechanical stimulation as a technique for horticultural applications under greenhouse conditions is discussed.
The Caricaceae is a small family of about six genera that includes the papaya and other less well-recognized fruit that are only known and consumed at a local level. Papaya (Carica papaya L.) is the most important species in the family, and it is a highly valuable fruit in most tropical and subtropical frost-free countries. However, other species could be of some importance in the near future, especially as valuable genetic resources. Even though the family is of considerable economic importance, its botany and taxonomy are not well known by growers and horticulturists. The taxonomy and botany of the Caricaceae is reviewed and discussed as well as its genera and species, its distribution, common names, and possible lines of evolution. Related molecular analysis is reported that confirms that the classification presented is justified.
Aarthi, S., 46:99 Abbott, J.A., 20:1 Adams III, W.W., 18:215 Afek, U., 30:253 Aharoni, N., 37:281 Albrigo, L.G., 34:277 Aldwinckle, H.S., 1:423; 15:xiii; 29:1 Allen, A.C., 38:357 Alonso, J.M., 34:197 Alsanius, B., 43:185 Aly, R., 33:267 Amarante, C., 28:161 Anderson, I.C., 21:73 Anderson, J.L., 15:97 Anderson, P.C., 13:257 Andrews, P.K., 15:183 Ascough, G.D., 34:417 Ashworth, E.N., 13:215; 23:1 Asokan, M.P., 8:43 Atkinson, D., 2:424 Aung, L.H., 5:45
In modern horticulture, fruit thinning must be performed to fulfill market demands. Although several advances in knowledge have been achieved in this field, the fruit industry is continuously evolving in terms of technical, economic, and environmental sustainability. In facing these changes, research does not always satisfy in a timely manner the strong demands from the productive sector. Fruit thinning remains an unpredictable cultural technique that may result in either over- or underthinning. For this reason, modeling tools based on research advances into early fruit abscission physiology may be useful for setting up decision support systems (DSSs) aimed at improving thinning performance. However, the fruitlet abscission process leading to cell separation at the level of the abscission zone involves multiple changes in cell structure, metabolism, and gene expression, making this research sector extremely challenging and complex. Ongoing climate change further increases this complexity, thus requiring more intensive and dynamic efforts that need to be coordinated at a higher level within an international R&D platform. With this perspective, a structural funding policy must be pursued not only by institutional agencies but also by the whole productive chain.
Eastern hemlock (Tsuga canadensis (L.) Carrière) is a slow-growing and long-lived conifer in the Pinaceae family. Its range extends from Nova Scotia west into Wisconsin and Minnesota and south along the Appalachian Mountains, northern Georgia, and Alabama, with outlier populations along the western range limits in Minnesota, Ohio, Indiana, Georgia, Alabama, Kentucky, and Tennessee. Eastern hemlock is a foundation species across its range that has transformational effects on its surrounding ecosystem. As of 2013, eastern hemlock has been listed as near threatened due to the presence of an invasive insect, the hemlock woolly adelgid (Adelges tsugae Anaand.), which is destroying populations in the eastern United States. Eastern hemlock has historically existed at its northwestern range limit in Minnesota in disjunct and marginal populations, and it is listed as endangered in the state. There are trees of known and suspected native provenance scattered across state and municipal parks and public gardens. In addition to its natural populations, eastern hemlock has long been an ornamental plant produced by the nursery industry and is propagated via vegetative cuttings and, less commonly, seed. The genetic diversity of native and cultivated eastern hemlock trees can be elucidated using DNA techniques such as microsatellite markers. Understanding the geographic areas that confer the greatest genetic diversity or sites that contain unique alleles can help prioritize the conservation and preservation of land. A combination of ecology, horticulture, conservation genetics, and strong professional partnerships will help ensure the survival of eastern hemlock in the United States.
Citron (Citrus medica L.) is the type species of the genus Citrus, one of the primary species of cultivated citrus, and a parent or ancestor of the commercially important acid citrus fruits. Southwestern China is a crucial center of origin and diversity for citron. The diversity of this species in China is extensive, but poorly documented until recently. Prized for its fragrance, citron played an important role in Chinese art and culture. Today, citron is grown in most of the warmer citrus-producing areas of China, and is used in Chinese traditional medicine, ornamental pot culture, and for human consumption as both fresh and processed products. In Chinese traditional medicine, dried citron is used as a tonic, to regulate Qi, the life force. Citrons are classified by fruit shape as either common (non-fingered) or fingered. In most of China, fingered citrons predominate because they are more suited to cultivation for medicinal and ornamental uses. Typically, common citrons grown in China have locules in which juice vesicles are absent, or are very scanty and rudimentary. 'Ning'er Giant', typically weighing 3–5 kg, sometimes reaching 8–10 kg, may be the world's largest citrus cultivar. Fingered citron trees vary in stature, cold hardiness, flower color, and other significant horticultural characteristics; the fruits vary in size, shape, number and thickness of fingers, proportion of fruits that are open or closed, and the point on the fruit at which the carpels become distinct. The distinctive forms of many named cultivars reflect different genotypes. There also exist in China genotypes that are intermediate in morphology between common and fingered citron. Putatively "wild" citron trees producing small fruits grow in forests, in semi-wild margins between natural and cultivated areas, and in private gardens in the subtropical forests of western and southern Yunnan. Scientists in China and elsewhere have paid increasing attention to citron germplasm resources during recent years.
