Genomic resources and genetic improvement of vital tropical and subtropical fruit crops: current status and prospects

Production of tropical and subtropical fruits has been increasing significantly faster than temperate fruits in recent years (FAO Production Yearbook, 1987). Although efficient vegetative propagation methods, i.e. grafting, air layering and removal of suckers, already exist for many of the most important tropical and subtropical fruit crops, the rapid expansion of plantings has nonetheless been impeded by serious shortages of clonal material, particularly of newly released, superior cultivars, e.g. ‘Arkin’ carambola (Averrhoa carambola). Among the underexploited tropical and subtropical fruits, whose production is often very important regionally, conventional vegetative propagation can be either quite inefficient, e.g. mamey sapote (Calocarpum sapota) and longan (Euphoria longan), or virtually impossible based upon several hundred years of experience, e.g. mangosteen (Garcinia mangostana). Therefore, many interesting tropical and subtropical fruits have not been exploited for lack of suitable clonal planting material.

There is much growing interest in the expansion of tropical and subtropical fruit production in the tropics, and in particular in the control of season and timing of flowering and fruit production. In the lowland tropics, temperatures are favourable year round for biomass production, and with increasing altitude, the available growing season is curtailed only by suboptimal cool temperatures; hence, an understanding of the control of flowering and fruiting is paramount in enabling major fruit harvest for key markets. Most of the tropical and subtropical fruits are available in the summer-rainy season (April–August) in Asian markets. A number of fruits like mango, lychee, guava, dragon fruit, jackfruit, pineapple and many minor fruits are available during this time of the year, sometimes causing market glut, and growers cannot get a good market price. Because of the high water content in most tropical and subtropical fruits, they are highly perishable, causing a high wastage in the supply chain from harvesting to consumers. On the other hand, most of these fruits are not available in the rest of the year, especially during winter. Management of phenology and the timing of flowering, therefore, is paramount to the productivity and success of production and marketing. Management of the timing of flowering and fruiting contributes to both over- and under-supply of fruit. Hence, out-of-season production of tropical and subtropical fruits is definitely more remunerative where it is possible by manipulating flowering time. In this review, four fruit crops (guava, pineapple, longan and dragon fruit) were selected because each fruit crop responded with a particular treatment for FI and/or YRP. Successfully off-season production of longan can be achieved by use of potassium chlorate as a FI chemical, guava by training of shoots in particular time of the year, pineapple with ethephon and calcium carbide and dragon fruit by supplemental lighting. Significance of the study What is already known in this subject? The technology developed for off-season production of various tropical fruits is not new; however, each fruit crop responds more to a particular treatment. Identifying the most appropriate technology for the growers of a particular crop or growers of composite orchards will ensure higher return. What are the new findings? The article does not present new information but compares the available technologies and suggests the best one for each of the four tropical fruits covered in this review. What is the expected impact on horticulture? Hopefully, the growers will adopt the technology to regulate flowering and out-of-season harvest according to market demand and to have more income.

In this paper the performances of fruit production and the resultant income generation from the same has been analysed in Himachal Pradesh. The study basically aims at analyzing the trends and patterns of fruit production and the income generation from it along with the investigation of annualized growth rates in the said aspects. The study has been conducted on the basis of the secondary sources of data and descriptive cum analytical methodology in terms of tabular and graphic presentations along with the simple growth rate formula has been used in the study. It has been found from the study that, out of the total fruit production in Himachal Pradesh, apple the state fruit of Himachal Pradesh recorded 77.03 percent production recently in 2020-21. The overall growth rate in production of apple in the whole study period of 10 years has been found to be 6.83 percent and the fruit production has been found to contribute to 12.56 percent of the annual state income in Himachal Pradesh followed by the production of different other tropical and sub-tropical fruits in the state. However, negative growth rate has been found in case of the production of apple and other tropical fruits in the recent times and the relevant causes behind such decline is also discussed. Based on the crucial findings in the study, policy suggestions are given to attract government and policy makers’ attention towards the unsatisfactory and underperformances of fruit production in the recent times in Himachal Pradesh.

North East Region (NER) of India comprises eight states namely Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura. Total geographical area of NER is 2.55 lakh km2, which is about 8% of India’s total area. Physiography of NER is divided into three divisions—Meghalaya plateau, northeastern hills and Brahmaputra valley. NE hills alone accounts for 65% of the total land area, Brahmaputra valley 22% and Meghalaya Plateau covers 13%. Average annual rainfall in the region is 2500mm. Less than 18% of net cropped area is under irrigation. NER enjoys suitable agro climatic condition for growing wide array of horticultural crops. With exception to mandarins and to a certain extent to banana and pineapple, majority of fruit crops in the region are largely grown in homestead gardens. The region has tremendous potential for growing all the subtropical, tropical and temperate fruit crops organically. From the Zone-wise, nutrient-wise consumption pattern of fertilizers during 2014-15 clearly depicts that in South Zone a total of 166.33, in West Zone a total of 84.64, in North Zone a total of 192.32, in East Zone a total of 161.08 while in North East Zone a total of only 82.63. NPK kg per hectare fertilizers are consumed. The major share of whatever little fertilizers consumed in the North East Zone largely goes to the plantation crops like tea, rubber as well as to the cereal crops grown in the region. The low fertilizer consumption pattern in the region clearly depicts farmers’ tendency of non using inorganic fertilizers for fruit production. This situation compelled the fruit production organically by default in the region. However, it would be a challenging task for the fruit growers of the region to produce fascinating fruit crops of the region organically not merely by default but primarily as well as substantially by practice of organic farming. State like Sikkim of the region from the beginning of the current year is already one step ahead in proclaiming to be the first state in the country to be organic. In addition, another NER state Tripura is already in limelight by proclaiming positions as Organic Pineapple Producer among the sixty Agri Export Zones of the country. Mizoram, Meghalaya and Assam states have taken initiative to produce mandarins, lemons, passion fruits and pineapples organically. Manipur Organic Mission Agency is planning organic production of mandarins, lemons and pineapples as a first step in six hill districts of the state. Arunachal Pradesh has formed state Soil Health Mission as an initial step for entry into systematic organic fruit production. With the existing diversified tropical, subtropical and temperate fruit crops in NER, exploitation of potentials of organic fruit production in the region would definitely be a giant step in making the entire NER as the Organic Hub for fruits in the country.

BackgroundFruit crops, including tropical and subtropical fruits like Avocado (Persea americana), Fig (Ficus carica), Date Palm (Phoenix dactylifera), Mango (Mangifera indica), Guava (Psidium guajava), Papaya (Carica papaya), Pineapple (Ananas comosus), and Banana (Musa acuminata) are economically vital, contributing significantly to global agricultural output, as classified by the FAO’s World Programme for the Census of Agriculture. Advancements in next-generation sequencing, have transformed fruit crop breeding by providing in-depth genomic and transcriptomic data. RNA sequencing enables high-throughput analysis of gene expression, and functional genomics, crucial for addressing horticultural challenges and enhancing fruit production. The genomic and expression data for key tropical and sub-tropical fruit crops is currently lacking a comprehensive expression atlas, revealing a significant gap in resources for horticulturists who require a unified platform with diverse datasets across various conditions and cultivars.ResultsThe Fruit Expression Atlas (FEAtl), available at http://backlin.cabgrid.res.in/FEAtl/, is a first-ever extensive and unified expression atlas for tropical and subtropical fruit crops developed using 3-tier architecture. The expressivity of coding and non-coding genes, encompassing 2,060 RNA-Seq samples across 91 tissue types and 177 BioProjects, it provides a comprehensive view of gene expression patterns for different tissues under various conditions. FEAtl features multiple tabs that cater to different aspects of the dataset, namely, Home, About, Analyze, Statistics, and Team and contains seven central functional modules: Transcript Information,Sample Information, Expression Profiles in FPKM and TPM, Functional Analysis, Genes Based on Tau Score, and Search for Specific Gene. The expression of a transcript of interest can be easily queried by searching by tissue ID and transcript type. Expression data can be displayed as a heat map, along with functional descriptions as well as Gene Ontology and Kyoto Encyclopedia of Genes and Genomes.ConclusionsThis atlas represents a groundbreaking compilation of a wide array of information pertaining to eight distinct fruit crops and serves as a fundamental resource for comparative analysis among different fruit species and is a catalyst for functional genomic studies. Database availability: http://backlin.cabgrid.res.in/FEAtl/.

Background Fruit crops, including tropical and subtropical fruits like Avocado (Persea americana), Fig (Ficus carica), Date Palm (Phoenix dactylifera), Mango (Mangifera indica), Guava (Psidium guajava), Papaya (Carica papaya), Pineapple (Ananas comosus), and Banana (Musa acuminata) are economically vital, contributing significantly to global agricultural output, as classified by the FAO's World Programme for the Census of Agriculture. Advancements in next-generation sequencing, have transformed fruit crop breeding by providing in-depth genomic and transcriptomic data. RNA sequencing enables high-throughput analysis of gene expression, and functional genomics, crucial for addressing horticultural challenges and enhancing fruit production. The genomic and expression data for key tropical and sub-tropical fruit crops is currently lacking a comprehensive expression atlas, revealing a significant gap in resources for horticulturists who require a unified platform with diverse datasets across various conditions and cultivars. Results The Fruit Expression Atlas (FEAtl), available at http://backlin.cabgrid.res.in/FEAtl/index.php, is a first-ever extensive and unified expression atlas for tropical and subtropical fruit crops developed using 3-tier architecture. The expressivity of coding and non-coding genes, encompassing 2,060 RNA-Seq samples across 91 tissue types and 177 BioProjects, it provides a comprehensive view of gene expression patterns for different tissues under various conditions. FEAtl features multiple tabs that cater to different aspects of the dataset, namely, Home, About, Analyze, Statistics, and Team and contains seven central functional modules: Transcript Information, Sample Information, Expression Profiles in FPKM and TPM, Functional Analysis, Genes Based on Tau Score, and Search for Specific Gene. The expression of a transcript of interest can be easily queried by searching by tissue ID and transcript type. Expression data can be displayed as a heat map, along with functional descriptions as well as Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. Conclusions This atlas represents a groundbreaking compilation of a wide array of information pertaining to eight distinct fruit crops and serves as a fundamental resource for comparative analysis among different fruit species and is a catalyst for functional genomic studies.

The effects of flooding calcareous soil on physiology and growth have been studied for several subtropical and tropical fruit crops including avocado (Persea americana Mill.), mango (Mangifera indica L.), carambola (Averrhoa carambola L.), and several Annona species. In calcareous soils that have a high pH, short-term flooding can actually be beneficial to subtropical and tropical fruit crops by increasing the solubility of particle-bound nutrient elements such as Fe, Mn and Mg due to flooding-induced decreases in soil pH. Additionally, flooding reduces the redox potential in the soil, resulting in Fe being reduced from Fe3+ to Fe2+, which is the cation metabolized by plants. As with other woody perennial crops, one of the early physiological responses of subtropical and tropical fruit trees to flooding is a decrease in stomatal conductance and net CO2 assimilation. If the flooding period is prolonged, lack of O2 (anoxia) in the soil results in a reduction of root and shoot growth, wilting, decreased nutrient uptake and eventual death. The flooding duration required to cause tree mortality varies among species, among cultivars within species, and with environmental conditions, particularly temperature. Several tropical and subtropical fruit crops have anatomical or morphological adaptations to tolerate prolonged flooding, such as development of hypertrophied stem lenticels, adventitious rooting or formation of porous aerenchyma tissue. For grafted trees, flooding-tolerance is conferred by the rootstock and not the scion. Therefore there is a possibility to increase flood tolerance of subtropical and tropical fruit crops by identifying or developing flood-tolerant rootstocks.

Chapter 7 - Application of ’omics technologies in tropical and subtropical fruit crops

Production and commercialization of tropical and subtropical fruits have strongly increased in the last decade, particularly in countries with subtropical and Mediterranean climates, with important developmental advances due to significant research efforts, including control of flowering, intensive cultivation systems and use of growth regulators. This chapter covers general aspects such as the definition, classification and importance of tropical and subtropical fruits and their environmental requirements. Due to the different growth behaviour of monoaxial and polyaxial species different case studies covering some of the main tropical and subtropical fruits, i.e. bananas and papayas (monoaxials) and avocado, mango and cherimoya (polyaxials) are treated separately regarding their edaphoclimatic requirements for production and crop management, making special emphasis in reproductive biology, a key factor on the adaptation of tropical and subtropical fruits to different environments.

High density planting (HDP) is a highly efficient and advanced production system of fruit cultivation. In most of the temperate tree and nut crops it is now commercially followed all over the world because of availability of suitable dwarfing rootstock to control tree vigor. Major tropical fruit crops are either propagated by suckers (banana, pineapple), seed (papaya) or by layering (guava) and grafting (mango). The use of dwarfing rootstocks, as in many temperate tree fruits, is not possible/available in most of the commercial tropical fruits for high density planting. High density planting is one of the novel methods to achieve high productivity per unit area both in short duration and perennial horticultural crops. High yield and high fruit quality can be achieved with a high-density orchard when the orchard has good light distribution throughout the tree canopy and there is a balance between vegetative growth and cropping. Many variables must be included in making a decision about spacing. Tree vigor and growth habit as influenced by cultivar and rootstock (where it could be utilized) are important. The ultimate limit on productivity of any crop is the amount of photosynthetically-active radiation (PAR) intercepted. Much of the planning that goes into the design of HDP orchards is actually based on average light interception over the life of the planting. This involves both minimizing the amount of light which strikes the ground and providing canopy structures in which the largest amount of canopy receives optimum light intensity. A tree with a large portion of its volume devoted to bearing has a greater potential for productivity than one with most of its volume devoted to tree support, middles or other functions. In India, HDP has been proved useful in many tropical and subtropical fruit crops e.g., mango, citrus, pineapple, banana, guava litchi, and papaya. The productivity of fruit crops depends on several factors, poor management of canopy architecture being the most important one. The fruiting potential of the trees is largely governed by their architecture, canopy density and photosynthetic efficiency. Canopy in a fruit tree refers to its physical composition comprising of the stem, branches, shoots and leaves. While, the canopy density is determined by the number, length and orientation of stem, branches and shoots. Tree canopy management, especially size control has become a priority for reducing production cost and increasing fruit yield and quality. The objective of canopy management is to optimize the plant model in such a way so that it may intercept maximum light by tree training, pruning, branch and tree orientation. Some of the basic principles in canopy management are: maximum utilization of the light, avoidance of the buildup of micro-climate congenial for the diseases and pests, convenience in carrying out the cultural operations, maximizing the productivity and quality and economy in obtaining the required canopy architecture.

ISHS XXX International Horticultural Congress IHC2018: II International Symposium on Micropropagation and In Vitro Techniques Steps towards mitigating challenges in the micropropagation of tropical and subtropical fruit and nut crops in South Africa

In order to realize the tropical fruit quality safety traceability, the paper proposes that using two-dimensional bar code (QR Code) technology constructs the tropical fruit quality safety traceability system. On the basis of the study of the two-dimensional bar code (QR Code) technology in Manufacturing Environment, author analyzes the elements involved of tropical fruit production and circulation, uses HACCP, FMECA and other technical methods, puts forward the key elements of the quality and safety of tropical fruit, uses country and industry relevant coding standard, and constructs tropical fruit quality safety traceability system based on two dimensional bar code (QR Code). Application shows that the tropical fruit companies or production bases by using the system improve the tropical fruit production safety management level, realize the tropical fruit quality safety traceability, promote tropical fruit industrialization and standardization management.

Tropical and subtropical fruit and starchy root and tuber crops are among the most important components of diets in many parts of the world (Tables 1 and 2). They are also important sources of hard currency income, either from the export of fresh or processed food or from the sale of secondary products. Recent trends in the growth of tropical fruit production suggest that consumers in many temperate countries are discovering tropical fruit (Table 2). There is currently a massive expansion of the tropical fruit industry in Central America, South America and in many Caribbean countries. Most tropical fruit, root and tuber crops have been vegetatively propagated for several hundred, and in some cases, for several thousand years. Clonal propagation methods that have been used have ranged from relatively sophisticated grafting techniques with some fruit cultivars (12) to direct planting of tuber or stem pieces with some of the starchy root and tuber plants. In this way, the unique genetic balance of plant selections has been maintained. With the passage of time, however, many of these clones have become highly vulnerable to increased disease pressure. Classic examples of this phenomenon during the twentieth century have been the devastation of ‘Gros Michel’ banana production in Central America by Panama disease and the more recent epidemic of black Sigatoka disease among cooking bananas (plantains) in the same region. Finally, the spread of acquired systemic viral and bacterial infections has been facilitated by clonal propagation methods. These diseases have become the most important factors that limit production of Citrus, yam, sweet potato, cassava, and various edible aroids.KeywordsSomatic EmbryoSomatic EmbryogenesisSweet PotatoFruit SpeciesPassion FruitThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Florida's tropical and subtropical fruit crop industries use various irrigation systems, including high-volume systems designed for irrigation and freeze protection, drip systems for herbaceous fruit crops (papaya, banana), and microsprinkler types, mainly for irrigation and fertigation. There continues to be a steady stream of potential tropical and subtropical fruit producers in Florida, many with little to no knowledge of the various types or purposes of various irrigation system that have been used successfully for the past 60 years. This new 9-page publication of the UF/IFAS Horticultural Sciences Department includes potential producers, Extension faculty and agents, and irrigation companies. Written by Jonathan Crane, Haimanote Bayabil, Edward A. Evans, and Fredy Ballen.https://edis.ifas.ufl.edu/hs1375

Os resíduos agroindustriais, coprodutos, podem servir para amenizar a falta de alimento para ovinos na região Nordeste e somam mais de 290 milhões de toneladas, representando perda de biomassa e de nutrientes, além de ser potencialmente poluidor de solos e corpos hídricos. O Brasil é o terceiro maior país produtor de frutas do mundo e o primeiro na produção de frutas tropicais, com 47 % das frutas consumidas in natura e 57 % processadas, cujo resíduo pode chegar a 50 % da biomassa original. A região Nordeste apresenta condições favoráveis para a fruticultura, possuindo mais de 30 pólos de produção que juntos produziram 11 297 984 toneladas de frutas, o que corresponde a mais de 55 % da produção das principais frutas tropicais do território brasileiro, com potencial de geração de 5 787 884 toneladas de coprodutos. As frutas estudadas foram o abacaxi, melão, caju, goiaba, mamão e maracujá que, de maneira geral representam fontes alimentares para os ovinos, apesar de terem restrições em proporção da dieta e que são diferentes para cada fruta. O processo de agroindustrialização de frutas no Brasil, devido aos mercados mais exigentes, tende a gerar coprodutos com menos variação na sua composição química, o que é benéfico ao setor pecuário devido à qualidade do coproduto gerado.