Desirable Horticultural Traits Research Articles

Gene action and hybrid vigour for yield, yield components and tolerance to the Two-Spotted Spider mite in summer squash

An investigation was conducted at Kaha Vegetable Research Farm in the Kaliobia Governorate from 2021 to 2023 with an aim to evaluate the performance of six inbred lines of summer squash and their fifteen crosses in both open field and plastic greenhouse conditions. The study spanned two successive summer seasons (2022 and 2023) and focused on assessing horticultural traits and resistance levels to the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Significant variations were observed in the mean performance of all traits among different genotypes. Analysis revealed significant differences in both general (GCA) and specific (SCA) combining abilities for all studied traits, except for the number of days to anthesis of the first female flower, indicating the presence of both additive and non-additive gene effects in traits inheritance. In the plastic greenhouse, genotype P3 exhibited the highest resistance with an average of 10.6 mites per 2 inches², while the cross P2 × P6 showed tolerance with an average of 4.4 mites per 2 inches². This study highlights the potential of new summer squash hybrids with desirable horticultural traits and resistance to the two-spotted spider mite. Additionally, parent 222/2 (P1) demonstrated the best combining ability for all traits, while parents 264 (P5) and 240/3 (P4) were the most effective combiners for total yield. Breeders may leverage these parents for genetic enhancement and the production of hybrids with superior horticultural qualities. Overall, this research provides valuable insights for researchers, breeders and farmers involved in the cultivation, breeding and utilization of summer squash in Egypt.

Breeding Strategies for Simultaneous Improvement in Anthracnose Disease Resistance and Economically Important Traits in French Bean

Background: French bean (Phaseolus vulgaris L.) production in the tropics is threatened by heavy incidence of anthracnose disease causing substantial crop loss when infection is at the early growth stages. Breeding strategies for tolerance against anthracnose disease along with enhanced productivity, and high pod protein content are to be formulated. Methods: Genotypes having broad genetic base and phenotypic diversity in 5 bush and 1 pole types were crossed in a 6 × 6 half diallel mating design to estimate combining ability, mode of gene action, and extent of heterosis for 11 quantitative traits. Result: The additive genetic effect was evident for percent disease index (PDI) of anthracnose and 10 pod weight. Rapid genetic gain can be achieved due to predominance of additive gene action in their control and can therefore be selected in early generation through simple breeding methods. Rest of the economic traits controlled by additive and non-additive gene effects could be improved through biparental mating, reciprocal recurrent selection, or diallel selective mating. Anthracnose disease tolerant and high yielding cultivars of might be developed utilizing parents, ‘Laxmi’, ‘Arka Sharath’ and ‘Vaishnavi-264’ with high gca effects. Although two cross combinations ‘Arka Sharath × Lakshmi’ and ‘Arjun × Arka Sharath’ showed significant heterobeltiosis in desired direction for PDI of anthracnose and other desirable horticultural traits but could not be exploited at commercial level due to complexity in hybridization. Identifying pure lines with tolerance against anthracnose disease and favorable horticultural attributes could be accomplished in segregating generations of the prospective hybrids.

Morphological, biochemical and sensory analysis of selected Actinidia callosa var. strigillosa female accessions from the existing wild populations in North Sikkim, India

ABSTRACT An analysis of wild kiwifruit (Actinidia callosa var. strigillosa) fruit samples from North Sikkim district of Sikkim state of Northeast India resulted in the identification of six promising female accessions, viz. SKNLA-11, SKNBC-01, SKNBC-02, SKNLC-02, SKNLC-07, and SKNZM-02. These selections exhibited significant variation in performance across desirable horticultural traits. Morphological parameters, including fruit weight (3.69–6.33 g), length (18.76- 26.71 mm), diameter (16.26- 19.76 mm), size (length × diameter) (342.56- 495.20 mm2), length-to-diameter ratio (1.03–1.57), stalk length (13.31–18.56 mm), and fruit yield (2.50- 8.50 Kg/vine), were assessed. Biochemical characteristics such as total soluble solids (17.20 −17.76 °B), titratable acidity (0.84–1.19%), total sugars (9.52–10.60%), reducing sugars (7.14–8.30%), non-reducing sugars (1.87–2.68%), sugar-acid ratio (8.26–11.33), ascorbic acid (31.20–41.60 mg/100g), and total phenols (33.31–94.88 mg GAE/100g) were examined. Sensory evaluation was carried out by a panel of judges, rating flavour (6.00–8.00), texture (5.40–8.20), aroma (5.80–8.50), taste (6.00–8.00) and overall acceptability (5.90–7.88) on a scale of 1 to 9. Notably, SKNBC-01, SKNLC-02, and SKNBC-02 excelled in overall acceptability. These selected accessions displayed significant variation in bloom date, anticipated harvest date, and harvesting period (in days).

Assessment of gene action association involved with economic traits of black carrot (Daucus carota)

Carrots (Daucus carota L.) are rich sources of vitamins, phytonutrients, bioactive compounds and health promotingproperties. Recent increased awareness of nutritional security has resulted in a dramatic increase in carrot consumption,necessitating increased carrot production by farmers and growers. Understanding the genetic design of economictraits including root length, root weight, root diameter, core diameter, and flesh thickness, as well as developing anappropriate breeding plan for these traits, will help accomplish those ambitious goals. Gene action experiments wereconducted at ICAR-Indian Agricultural Research Institute during 2012–15 in order to estimate the type and magnitudeof gene action in order to develop a breeding strategy for recognizing segregants with desirable horticultural traits.Four inbred lines such as Pusa Asita, Pusa Rudhira, Pusa Kulfi, Pusa Meghali were used to develop three crosses, viz.Pusa Asita × Pusa Kulfi, Pusa Asita × Pusa Meghali, Pusa Asita × Pusa Rudhira to achieve the objectives. The findingsconfirmed that the exact composition of gene effects varied through crosses and demonstrated the role of additiveas well as non-additive gene effects in the inheritance of different traits, with a preponderance of the latter. Due tothe parallel function of complementary gene effects, non-epistatic gene interactions for economic yield contributingtraits have been found; thus, hybrid exploitation could be efficiently used by heterosis breeding by using favourablepositive [h] and [l] gene interaction and effects. This genetic information is more helpful to formulate suitable breedingmethodology for identifying the segregants with desirable horticultural traits.

Flaming Phlox and the Ubiquitous Powdery Mildew Disease

Phlox is a diverse genus of ornamental plants that is native to the North American continent. These popular plants, which are known for flowers with “the color of glowing flame”, are particularly appreciated in naturalistic arrangements and increasingly emphasized in native gardens for their ability to attract pollinators. Despite the plant’s popularity, the main limitation to its cultivation is the fungal disease powdery mildew (PM). Hence, cultivars deployed through the years have been selected not just for desirable horticultural traits but also for resistance to PM. Although some studies on the Phlox-PM pathosystem have begun to unravel the mechanisms underpinning host-pathogen interactions, numerous questions remain unanswered, including what are the genes involved in the retarded senescence of the infected host tissue, what are the molecular mechanisms associated with the host ontogenic resistance, and what is the role of phytohormones in the resistance of Phlox to PM? PM pathogens, already predominant on Phlox, are now likely to be ubiquitous due to the exchange of plants throughout the world. Research into the genetic diversity of Phlox-PM populations will help identify the routes of disease spread and evolutionary potential of the pathogens. Here, we review what is known about Phlox and the PM disease, and we identify knowledge gaps that have yet to be addressed.

Species diversity and phylogeography of Cornuskousa (Asian dogwood) captured by genomic and genic microsatellites.

Cornus kousa (Asian dogwood), an East Asia native tree, is the most economically important species of the dogwood genus, owing to its desirable horticultural traits and ability to hybridize with North America‐native dogwoods. To assess the species genetic diversity and to better inform the ongoing and future breeding efforts, we assembled an herbarium and arboretum collection of 131 noncultivated C. kousa specimens. Genotyping and capillary electrophoresis analyses of our C. kousa collection with the newly developed genic and published nuclear genomic microsatellites permitted assessment of genetic diversity and evolutionary history of the species. Regardless of the microsatellite type used, the study yielded generally similar insights into the C. kousa diversity with subtle differences deriving from and underlining the marker used. The accrued evidence pointed to the species distinct genetic pools related to the plant country of origin. This can be helpful in the development of the commercial cultivars for this important ornamental crop with increased pyramided utility traits. Analyses of the C. kousa evolutionary history using the accrued genotyping datasets pointed to an unsampled ancestor population, possibly now extinct, as per the phylogeography of the region. To our knowledge, there are few studies utilizing the same gDNA collection to compare performance of genomic and genic microsatellites. This is the first detailed report on C. kousa species diversity and evolutionary history inference.

Evaluation of Genetic Diversity in Korean Fir Cultivars Based on Microsatellite and Cytoplasmic Markers

Korean fir (Abies koreana) has been cultivated for less than 100 years, mainly in the United States and Europe. Using nuclear microsatellite, mitochondrial, and chloroplast markers, we investigated the origin of cultivated korean fir from South Korea (KC group) as well as the United States and United Kingdom (EU group), and compared these samples to published data from wild populations. All genotypes in the EU and KC groups were most closely related to the wild individuals from Mt. Hallasan, the southernmost A. koreana population on Jejudo Island (South Korea). However, the presence of the chloroplast haplotypes clustered with Abies balsamea in two EU cultivars and the higher diversity values of the EU group compared with the wild individuals from Mt. Hallasan infer a certain level of introgression from different species during cultivation. The EU group had a higher inbreeding coefficient and linkage disequilibrium, and a smaller proportion of rare alleles, than the wild populations. This suggests that the genetic characteristics of korean fir cultivars reflect strong artificial selection pressure for desirable horticultural traits and asexual reproduction. Last, this genetic background study suggests that the other wild populations in the Korean peninsula can serve as valuable genetic resources for future breeding.

Characterization of induced mutants and their hybrids of tomato (Solanum lycopersicum L.) for growth, yield and fruit quality traits to explore the feasibility in future breeding

Characterization of tomato mutants affecting growth, yield and fruit quality traits could provide valuable insights into the underlying biology vis-a-vis source of new alleles for breeding programs. Knowing the presence of useful genes and alleles would help in making decisions on the multiplication of accessions and the maintenance of seed stocks when responding to an expected higher demand for materials. Such information may also help in making decisions on heterogeneous accessions, where only some genotypes may possess useful alleles. Thus, the present study was undertaken to characterize three induced mutants, two parental lines and three hybrids for 9 qualitative and 27 quantitative traits to utilize useful genes in tomato breeding, and to assess genetic variability and character associationship among 27 quantitative characters to identify important selection indices. The variation was observed in the habit of growth, type of blossoms, fruit form and the color of the immature fruit among mutants. A significant effect of mutant genes is recorded in a heterogeneous state to express desirable horticultural qualities in hybrids. Partial effects to excessive dominance have been found to inherit fruit yields and other horticultural qualities. Exploit the hybrid Berika × B Mut-1 appeared as the most promising and could either commercially use for both table and processing purpose after critical evaluation or could be utilized in segregating generation to identify pure lines with desirable horticultural traits. The most important traits for high heritability with high genetic advance are: flower cluster per plant, flower per cluster, fruit per plant, number of locules per fruit, total chlorophyll content of leaf, total chlorophyll content of immature fruits, chlorophyll a content of immature fruits, chlorophyll b content of immature fruits, lycopene content of mature fruits and ascorbic acid content, suggesting selection would be rewarding for improvement of these traits. The top priority should be given to selection based on lycopene content, chlorophyll a content of leaf, ascorbic acid content, fruit number per plant and chlorophyll b content of immature fruit for yield improvement and could be considered while formulating selection indices in the improvement of tomato.

Evaluation of ber genotypes for fruit yield and quality attributes

The objective of the study was to select promising ber genotype having least stone percentage maintained at Issapur farm, ICAR-NBPGR, New Delhi. For this purpose, 12 genotypes were selected and evaluated for their desirable horticultural traits during 2017–18 and 2018–19. Fruit maturity was recorded earliest during first week of February in Gola followed by IC-0625596 which matured during last week of February. Among all the cultivars, the Umran matured at the last. Much variation with respect to fruit shape, colour and stone size was observed in all the genotypes. The fruit shape of Umran was found as ovate oblong, Seb with oval shape, Gola with round shape and the genotypes IC-0625596 with oblong with apex as broadly pointed. Highest fruit weight (35.40 g) was recorded in Umran, while it was found minimum in Aliganj selection (17.4 g). The maximum pulp weight noticed in Umran (28.08 g) and least stone weight was found in IC-0625596(1.70g). On pooled basis, the least pulp stone ratio was recorded in accession IC-0625596 (21.15). Highest TSS (17o Brix) was recorded in IC-0625596 genotype followed by Gola (16.8o Brix).

Screening for resistance against major lepidopteran and stem weevil pests of amaranth in Tanzania

Insect pests pose major challenges to optimum productivity of amaranth in Africa and Asia. The use of insecticides is the main control strategy, but is expensive and may pose health and environmental concerns, especially if proper care is not taken. Host plant resistance offers a cheap and sustainable pest management alternative. Open field experiments were conducted during two cropping seasons in 2016 and 2017 to screen 35 amaranth accessions and lines for resistance to leaf-webbers and stem weevils. The diversity (H) of lepidopteran defoliators and their parasitoids on each accession ranged from 0.00 to 1.57 and 0.00 to 1.65, respectively during the long rainy season and from 0.00 to 1.58 and 0.00 to 1.01 in the short rainy season. Accessions VI036227, RVI00027, VI054569, VI033487, VI044432, VI048076, VI049639, VI049530 and VI049698 had high levels of pest resistance with significantly lower infestations (≤ 11.11 ± 2.14%) and damage (≤ 68.06 ± 3.90%) by leaf-webbers and leaf-worms. Stem weevil infestations ranged from 68.70 ± 2.0% to 90.42 ± 1.0% during the long and short rainy seasons, respectively. Accessions VI047517-B, VI036227 and VI056563 had the least stem weevil infestations (< 62.5%) but differences among accessions for damage incidences were non-significant. Parasitism was observed in all the accessions except seven of them. Amaranth accessions exhibiting pest resistance or at least non-preference traits are important for success of breeding programs. The importance of deploying such accessions to breed for improvement of susceptible lines (by introgression) or their release to farmers, if they have desirable horticultural traits that are required by vegetable producers and consumers, for effective management of amaranth pests is also discussed.

Current Status of Early Blight Resistance in Tomato: An Update.

Early blight (EB) is one of the dreadful diseases of tomato caused by several species of Alternaria including Alternaria linariae (which includes A. solani and A. tomatophila), as well as A. alternata. In some instances, annual economic yield losses due to EB have been estimated at 79%. Alternaria are known only to reproduce asexually, but a highly-virulent isolate has the potential to overcome existing resistance genes. Currently, cultural practices and fungicide applications are employed for the management of EB due to the lack of strong resistant cultivars. Resistance sources have been identified in wild species of tomato; some breeding lines and cultivars with moderate resistance have been developed through conventional breeding methods. Polygenic inheritance of EB resistance, insufficient resistance in cultivated species and the association of EB resistance with undesirable horticultural traits have thwarted the effective breeding of EB resistance in tomato. Several quantitative trait loci (QTL) conferring EB resistance have been detected in the populations derived from different wild species including Solanum habrochaites, Solanum arcanum and S. pimpinellifolium, but none of them could be used in EB resistance breeding due to low individual QTL effects. Pyramiding of those QTLs would provide strong resistance. More research is needed to identify additional sources of useful resistance, to incorporate resistant QTLs into breeding lines through marker-assisted selection (MAS) and to develop resistant cultivars with desirable horticultural traits including high yielding potential and early maturity. This paper will review the current understanding of causal agents of EB of tomato, resistance genetics and breeding, problems associated with breeding and future prospects.

Genetic variability in wood apple (Feronia limonia) from Gujarat

Considering the wide genetic diversity in wood apple (Feronia limonia) in terms of fruit shape, size, colour and qualitative characters, an extensive survey of diversity rich area of Gujarat was made and twenty five genotypes in the form of fruits were collected from the different locations during 2015-16 to identify elite genotypes having desirable horticultural traits. All the existing trees are of seedling origin which offer a great scope for selection of suitable genotypes of high yield potentiality with good fruit quality traits having precocity in bearing, less spine intensity and other desirable characters. Variations in morphological characters were noticed in the naturally grown trees at their locations, whereas chemical analysis was done in laboratory of the station. Fruits of genotype, viz. GW-1, GW-4, GW-12, GW-14, GW-16, GW-18, Gw-20 and GW-24 were observed to be round, whereas flattened round in GW-2, GW-5, GW-6, GW-8, GW-9, GW-10, GW-13, GW-17, GW-21and GW-23; triangular in GW-7 and GW-11, and oblong in GW-3, GW-15, GW-19, GW-22 and GW-25 fruit shape was observed. Physico-chemical analysis of fruits divulged that the fruit weight ranged between 156.45-432.93g, while fruit length and width between 5.25-9.46 cm and 5.10-9.29 cm, respectively. Shell thickness, shell weight, pulp weight, number of seeds per fruit and seed weight per fruit ranged between 0.31 to 0.47cm, 67.94-109.77g, 80.04 to 319.32g, 132.34 to 525.81 and 2.36 to 7.93g, respectively. Results of study revealed that the different genotypes exhibited wide range of variability in qualitativecharacters, viz. total soluble solids (11.07-19.36 0Brix), acidity (3.23-6.86%), ascorbic acid (7.08-19.60mg/ per100 g), potassium (1.29-1.86%), phosphorus (0.037- 0.078%), calcium (0.11- 0.39%), magnesium (3.18-5.92 %), sodium (3.07-7.54%) and pectin content (1.39-1.65%), among all the genotypes studied for their qualitative characters.

Heterobeltiosis, potence ratio and genetic control of processing quality and disease severity traits in tomato

Five inbred lines of tomato were crossed in a half diallel fashion to estimate the combining ability, mode of gene action, extent of heterobeltiosis and dominance effects in the inheritance of fruit yield, processing qualities and disease severity traits. A preponderance of non-additive gene action was detected for all studied characters except fruit weight, indicating that heterosis breeding is an appropriate strategy for their improvement. Maximum heterobeltiosis was observed for the percent disease index (PDI) of tomato leaf curl viruses (ToLCV), followed by the number of locules per fruit, PDI of early blight, fruit yield per plant, lycopene content of fruit, vitamin C content of fruit, total soluble solids content of fruit and acidity content of fruit. Partial- to over-dominance effects were involved in the inheritance of the studied traits. Three lines (CLN 2777E, BCT-115 and CLN 2777F) were identified as potential donors. We recommend that two hybrids (CLN 2777 F × CLN 2777 E and CLN 2777E × Ailsa Craig fulgens) would be appropriate for commercial use following further evaluation of their traits, as they exhibit desirable horticultural traits, particularly in the tropics.

Using Cut–Column Pollination Method to Overcome Crossing Barriers in Phalaenopsis Sunrise Goldmour 'KHM637'

Crossing barriers occur frequently when crossing between commercial Phalaenopsis cultivars with desirable horticultural traits are attempted. In this study, Phalaenopsis Sunrise Goldmour 'KHM637', a tetra- ploid with 2n=4x=76 chromosomes, known to be difficult in hybridization was chosen to examine crossing barriers and to explore the cut-column pollination method to overcome these barriers. P. Sunrise Goldmour 'KHM637' was either self-crossed, or used as the pollen or pistillate parent in reciprocal crossings with three tetraploid cultivars, including P. Brother Irene Irene 'Feng Fong', P. Sogo Yukidian 'V3', and P. Tai Lin Red Angel 'V31' that do not exhibit breeding barriers. Results showed that both stigma cavity closure and pollen tube growth did not occur when P. Sunrise Goldmour 'KHM637' was used as the pistillate parent. No offspring was obtained when using P. Sunrise Goldmour 'KHM637' as either pollen or pistillate parent. To explore performance of cut-column pollination method, P. Sunrise Goldmour 'KHM637' was used as the pistillate parent, after the removal of the upper part of column but with the stigma cavity intact, and then pollinated with pollinia of these three tetraploid cultivars and one species, P. violacea, respectively. The results showed that 22.2%-100.0% capsule sets were achieved from the four combinations, and offsprings were successfully obtained from three combinations. The authors suggested that the cut-column pollination method be applicable to other Phalaenopsis cultivars with similar crossing behaviors of P. Sunrise Goldmour 'KHM637' for overcoming the crossing barriers, and the applicability of the given method tended to be less limited to pollen parents without breeding barriers.

Molecular and Horticultural Characteristics of In vitro Induced Tomato Mutants

In addition to the traditional breeding approaches, genetic variability in tomato can be induced also by means of mutagenesis. The objective of this study was to develop an In vitro technique suitable for mutation induction on tomato and characterize them by RAPD and SSR markers as well as horticultural characteristics. The influence of various concentrations (0, 0.07, 0.14 and 0.25%) of the chemical mutagen, Ethyl Methane Sulfonate (EMS), on the in vitro shoot formation from cotyledon explants of two tomato cultivars was studied. The percentage of responding explants ranged from 45.2 to 95% in dependence on genotype and EMS concentrations. Two PCR-based techniques, RAPD and SSR, were used for analysis of genetic variations in regenerated plants from in vitro cultures combined with EMS treatment (0.25%). The percentage of polymorphism detected by RAPD and SSR primers reached 25.64%. Grouping of the original cultivar and their mutants indicated the genetic distinctness as they are placed in different clusters/groups far from each other. Mutants regenerated from the wide cultivated cultivar in Egypt (Super strain B) were evaluated with their origin cultivar in a field experiment for yield potential and fruit quality. The results revealed that the mutants were differed in number of branches, early and total yield, average fruit weight, fruit firmness and TSS content. Moreover, mutant lines S1, S3, S6 and S13 had some desirable horticultural traits and could be used in improving tomato crop by breeding programs or they could be considered as new breeding lines.

UPDATE ON NEW MANGIFERA SPECIES IN FLORIDA, USA

Several Mangifera species have been collected and are under evaluation at Fairchild Tropical Botanic Garden in Soutn Florida, FL, USA over the past 15 years. M. odorata, M. casturi, M. lalijiwa, M. quadrifida, M. laurina and a putative M. odorata/M. foetida hybrid have been grafted successfully on ‘Turpentine’ rootstock and trees have been grown in the field for 14 years. All of these species have bloomed and fruited with reasonable reliability over this time. In addition, many of the species have withstood temperatures as low as 29F for more than 5 hours with only minimal damage. Temperature does not appear to be a reliable inducer of bloom for these species growing in the field. Additional investigation is necessary, but Mangifera species also have shown a high degree of anthracnose tolerance under Florida conditions, but many have shown severe susceptibility to leaf and twig bacteria infection. The fruit of each species is unique in terms of color, appearance and eating quality, and all have potential as fresh fruit given proper selection of clones with superior fruit quality. M. griffithii, M. quadrifida, M. merilli and M. lalijiwa have performed better with M. casturi as an interstock. M. caesia, M. foetida, M. pajang and some unidentified species have not been successfully grafted on M. indica and no successful interstock has been found. INTRODUCTION In Southeast Asia there is a wide diversity of Mangifera species that bear edible fruit, with 69 taxonomically recognized (Kostermans and Bompard, 1993). Among these species, Mangifera indica is the most important commercial fruit crop. Two decades ago Kostermans and Bompard (1993) outlined the potential of Mangifera species as edible fruit crops, rootstocks, and as sources of genetic diversity for the future breeding of disease resistance, and desirable horticultural traits in the modern mango. The importance of conserving these species and their genetic potential has been clearly recognized by the scientific community, but there is almost no practical horticultural information available about their suitability for propagation, their care and domestication. More than 16 Mangifera species from Borneo, peninsular Malaysia, and Thailand have been accessioned into the genetic collections of Fairchild Tropical Botanic Garden since 1994 (Campbell and Ledesma, 2002). These species were introduced as clonal material for each species; however, information about potential graft compatibility of was not readily available in this hemisphere. The process was undertaken by trial and error and there have been many failures in establishment of these species. The objective of this work is to detail the progress made with the establishment of Mangifera species for use in future breeding with M. indica and for the development of new ornamental, home garden, estate and commercial crops. GENERAL METHODOLOGY All collected material was brought to the United States as budwood. The entry of seed material is not allowed due to seed weevil and since many of these species are monoembryonic there would have been no advantage to the introduction of superior selections without clonal material. All species were grafted with cleft of veneer grafts depending on the size of the scion and the rootstocks available. Most grafts were made when nighttime temperatures were 20C or higher. The rootstocks used were ‘Turpentine’ imported from Costa Rica and interstocks of M. casturi and M. odorata. The M. casturi and M. odorata interstocks were from accessions originating in Australia and Brazil, respectively. Proc IX Internationa Mango Symposium

‘Lufkin Red’ and ‘Lufkin White’ Winter-hardy Hibiscus (Hibiscus ×laevis All.)

Winter-hardy hibiscuses are herbaceous perennials that regenerate from root buds each spring in USDA hardiness zones 5 through 9. Colloquially known as Rose Mallows, the most recent taxonomic revision (Blanchard, 1976) recognizes five species (Hibiscus coccineus Walter, Hibiscus dasycalyx Blake & Shiller, Hibiscus grandiflorus Michaux, Hibiscus laevis Allioni, and Hibiscus moscheutos L.) that comprise the North American taxon Hibiscus L. sect. Muenchhusia (Heister ex Fabricium) O. Blanchard (Malvaceae) (Small, 2004). A number of additional taxa associated with H. moscheutos have been variously recognized historically as varieties, subspecies, or distinct species. Primary among these are Hibiscus moscheutos subsp. palustris L., native to the northeastern United States, and Hibiscus moscheutos subsp. incanus Wendl., indigenous to the southeastern coastal plain (Blanchard, 1976). Native populations prefer wetland habitats such as flood plains but are tolerant to wide fluctuations in soil moisture. Rose mallows are long-day plants (Warner and Erwin, 2001) that flower from late spring through fall. Flowers last for a single day with color varying from scarlet rose in H. coccineus to white, lavender, and pink shades in the other four species. Studies of pollination in H. moscheutos indicate that the species is generally self-compatible but that the trait is variable with some lines rapidly develop inbreeding depression in progeny (Snow and Spira, 1993). The five species have a shared chromosome number of N =19, but artificial hybridization studies resulted in grouping the species into two groups based on seed set (Wise and Menzel, 1971). Hibiscus grandiorus and H. moscheutos (Group I) were entirely interfertile, and H. coccineus and H. laevis (Group II) were also interfertile, but crosses between groups produced few viable seed. Although Wise and Menzel (1971) did not include H. dasycalyx in their studies, subsequent work has shown that H. dasycalyx is closely related to H. laevis (Klips. 1995; Small, 2004) and clearly belongs in Group II. Although breeding of rose mallows has focused on developing new clones with improved horticultural traits (Malinowski et al., 2012) such as branching and flower color, there is a need for clones with improved disease resistance, particularly in the southeastern United States. Both ‘Lufkin Red’ and ‘Lufkin White’ have desirable horticultural traits in combination with demonstrated high levels of field resistance to the leaf spot complex (Pirone, 1970) that is problematic on winter-hardy hibiscus clones in areas with warm nights and high humidity.

Generation mean analysis to estimate genetic parameters for desirable horticultural traits in garden pea (Pisum sativum)

Generation means analysis was carried out to estimate the nature and magnitude of gene action in order to formulate breeding strategy for identifying the segregants with desirable horticultural traits and resistance to powdery mildew disease. Two commercially grown powdery mildew susceptible varieties Azad P-I and Green Pearl and three resistant lines DPP 9411, DPP 9418-06 and Sugar Giant were used to develop three crosses, viz. Green Pearl × Sugar Giant, DPP 9411 × DPP 9418-06, and Azad P-I × Sugar Giant to achieve the objectives. The presence of epistatic interaction for majority of the traits in all three crosses was observed as reflected by the significance of simple additive-dominance model. The results revealed that the nature and magnitude of gene effects differed in different crosses and showed the importance of additive as well as non-additive gene effects in the inheritance of different characters with preponderance of the latter. In view of the parallel role of additive and non-additive gene effects, selection in the segregating generations should be delayed to later generations to diminish the dominance gene effects. Duplicate type of epistasis was also found for some of the traits in certain cross combinations whose effect can be eliminated by following sophisticated selection procedure such as reciprocal recurrent selection and/or biparental mating in early segregating generations for the development of high- yielding garden pea varieties with desirable horticultural traits.

Screening and Characterization of 11 Novel Microsatellite Markers from Viburnum dilatatum

Viburnum dilatatum is a popular and economically important ornamental shrub. The wide range of desirable horticultural traits, paired with a propensity for seedlings to become invasive, has created interest in the genetics and breeding of this species. To investigate the genetic diversity of V. dilatatum, microsatellite loci were identified from a GT-enriched genomic library constructed from V. dilatatum ‘Asian Beauty’. Eleven microsatellite loci have been characterized on a group of 16 different related V. dilatatum cultivars and hybrids. Two to 12 alleles were identified per locus, and the polymorphism information content (PIC) values ranged from 0.36 to 0.87. Expected heterozygosity (He) ranged from 0.48 to 0.88 and observed heterozygosity (Ho) ranged from 0 to 0.73. This set of molecular markers also exhibited expected transferability between various V. dilatatum cultivars and two hybrids with V. japonicum. As a consequence, these markers will aid in breeding for new cultivar development, assist with early detection and screening of plants that have escaped cultivation, and are expected to help in refining the phylogenetic relationship of V. dilatatum to other species and genera within the Adoxaceae.

‘Mountain Majesty’: A Tomato Spotted Wilt Virus-resistant Fresh-market Hybrid Tomato and Its Parents NC 714 and NC 1CS

‘Mountain Majesty’, the F1 hybrid of NC 714·NC 1CS (Fig. 1), resulted from a tomato breeding effort to develop a superior largefruited hybrid tomato with improved fruit color based on the crimson (og) gene combined with fusarium wilt, verticillium wilt, and TSWV resistances adapted to vine-ripe production in North Carolina (NC). NC 714 resulted from selfing NC 03113, the F1 hybrid of Fla 8044 · NC 00318–15(x)-1 (Fig. 1). Fla 8044 is a large-fruited, hightemperature fruit set line with desirable horticultural traits and multiple disease resistance genes obtained from the University of Florida tomato breeding program. NC 00318–15(x)-1 is an F2 selection obtained by crossing a male sterile version of NC 84173 with an F3 generation line derived from selfing the North Carolina State University (NCSU)-released hybrid ‘Mountain Crest’ (NC 84173 · NC 1 rinEC) (Gardner, 2006). The crimson gene in NC 714 was derived from the NC 1rinEC parent of ‘Mountain Crest’ and Fla 8044. The objective of breeding NC 714 was to incorporate desirable fruit characteristics and superior combining ability from NC 84173 (Gardner, 1992) together with the crimson gene for increased red fruit color and lycopene content. Single plant selections were made for large fruit size, high yield, and other desirable horticultural traits in the F2 through F5 generations derived from selfing NC 03113. NC 1 CS resulted from selfing NC 056, the F1 hybrid of NC 123S ·NC 0255(x)-1 (Fig. 1). NC 123S, which combines single dominant gene resistances to TSWV, fusarium wilt race 3, and nematodes (Sw-5, I-3, Mi genes) and was released from the NC breeding program. ‘Amelia’ F1 hybrid, from which NC 123S was developed, is a codeveloped hybrid using NC 111F-2(98) as a source of the I-3 gene for fusarium wilt race 3 resistance crossed with a Clause Seed Company proprietary line having the Sw-5 and Mi genes. NC 0255(x)-1 is an outstanding large-fruited selection with the crimson gene that traces its pedigree back to breeding lines and cultivars developed in the NC tomato breeding program over a 25year period (Fig. 1). The source of the crimson gene in NC 0255(x)-1 is ‘Suncoast’, an inbred cultivar released from the University of Florida breeding program.