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Worldwide, there are cuurently more than 60 germplasm banks that contain tomato (Lycopersicon esculentum) collections ranging is size from a few dozen to several thousands of accessions. In the utilization of these genetic resources sampling from only one germplasm bank may result in limiting available genetic diversity, whereas sampling from several germplasm banks may result in unnecessary redundancy. The current lack of knowledge regarding the relative magnitudes of genetic diversity contained within different collections makes it difficult to develop a core collection that maximizes genetic diversity. Two large tomato collections are housed at the Asian Vegetable Research and Development Center (AVRDC), Sanhua, Taiwan, R.O.C., and the Centro Agronomico Tropical de Investigacion y Enseoanza (CATIE), Turrialba, Costa Rica. Ninety-six accessions from CATIE and 102 accessions from AVRDC were randomly sampled from each base collection. The total of 198 accessions were charcterized for 103 polymorphic RAPD molecular marker bands. The results indicated that the two germplam banks sampled different genetic diversity. In addition, the magnitude of genetic diversity was greater in the AVRDC collection compared to CATIE.

High-temperature fruit set (heat tolerance) is a critical trait of tomato (Lycopersicon esculentum Mill.) cultivars targeted for lowland wet season production in the tropics and subtropics. Heat-tolerant Asian Vegetable Research and Development Center (AVRDC) tomato line CL5915-93D4-1-0-3 (CL5915) is a valuable source of heat-tolerance genes for tomato genetic improvement. The gene action of heat tolerance in CL5915 was determined by evaluating the F₁, F₂, BCP₁, and BCP₂ of a cross between CL5915 and heat-sensitive line UC204A for fruit set traits in two wet-season trials at AVRDC. Parent-offspring regression of F₂-derived F₃ (F_2:3) family means on the F₂ plants from CL5915 × UC204A was used to estimate the heritability of F₂ single plant selection for heat tolerance. Mean percentage of fruit set and fruit number per cluster of the F₁ and BCP₁ exceeded midparent values and were not significantly different from those of CL5915, indicating complete dominance for heat tolerance. Generation means analyses indicated that a model including simple additive and dominance effects adequately explained the inheritance of mean fruit number per cluster both years. For mean percentage of fruit set, a model including simple additive-dominance effects produced an adequately fitting model in the 1996 season but the best-fitting model included an epistatic component in the 1997 season. Heritabilities estimated for fruit set traits in 1996 and 1997, respectively, were: 0.31 and 0.21 for percentage of fruit set; 0.28 and 0.14 for mean fruit number per cluster; and 0.53 and 0.15 for flower number per cluster. The low heritabilities for percentage of fruit set and mean fruit number per cluster under high temperatures imply that single plant selection in the F₂ for heat tolerance from crosses involving CL5915 is not effective and that selection should be based on replicated family testing in the F₃ and later generations.

Amaranths (Amaranthus sp.) are a popular leafy vegetable grown and consumed by resource-poor people in many African countries. Greater awareness of the importance of nutritious foods has increased demand by African consumers for amaranth. Presently, most African farmers grow low-yielding local varieties of variable seed quality. High-yielding amaranth varieties that are adapted to the major agro-ecologies of eastern and southern Africa possess key traits needed by male and female farmers and meet diverse market preferences are required. The objective of this study was to identify amaranth lines adapted to major amaranth production environments in Kenya and Tanzania using a gender-disaggregated farmers participatory approach to explore possible gender differences in trait and variety preferences. Twenty amaranth entries were evaluated for vegetable yield, agronomic traits, and organoleptic taste tests in replicated, farmer-participatory variety selection trials at one location in Kenya and at four locations in Tanzania. Differences among entries (G), locations (E), and G × E interaction were significant or highly significant for marketable vegetable yield. Location followed by entry was the most important factor that explained differences in yield. G and G × E interaction biplot analysis classified the five locations into two different mega-environments, mainly based on altitude, temperatures, and soil characteristics. Marketable vegetable yield was positively correlated with leaf length, plant height, and the selection scores of female and male farmers at almost all locations. Selection scores of female and male farmers were positively correlated, indicating that male and female farmers shared similar amaranth variety preferences. Farmers identified and ranked important traits that can be used by breeders to design amaranth product profiles and develop amaranth breeding objectives. Lines combining high yield with high farmer and consumer preference scores have been retained for distinctiveness, uniformity, and stability tests for possible release as commercial varieties.

Bacterial wilt (BW), caused by Pseudomonas solanacearum E.F. Smith, is one of the most destructive disease of tomato (Lycopersicon esculentum Mill.) in the tropics. Twenty tomato lines/accessions previously identified as BW-resistant were evaluated for BW reaction in fields providing high disease pressure at Subang, Indonesia; Los Baños, Philippines; Malaysian Agricultural Research and Development Institute (MARDI), Kuala Lumpur; Asian Vegetable Research and Development Center (AVRDC), Taiwan; and Taiwan Seed Improvement and Propagation Service (TSIPS). Entries also were tested in the greenhouse at the AVRDC with a P. solanacearum strain from Taiwan (Pss4) using a drench inoculation method. Objectives of the study were to identify stable sources of BW resistance for southeast Asian tomato breeding programs, and to determine the correlation between field and greenhouse reactions. Mean entry survival was 21.6% at Subang, 31.9% at Los Baños, 76.7% at the AVRDC, 93.6% at Malaysia, and 93.3% at TSIPS, indicating that most entries were resistant at MARDI and the Taiwan locations but susceptible at Subang and Los Baños. L285 (mean survival = 83.8%) and CRA 84-58-1 (mean survival = 79.4%) were the most resistant entries in the field trials. Mean survival (70.1%) of CRA 66-derived entries was significantly better than the mean of entries with resistance derived from UPCA 1169 or UPCA 1169 plus `Venus' or `Saturn'. Mean survival of AVRDC entries bred in the 1980s (59.4%) was significantly greater than mean survival of AVRDC lines bred in the 1970s (45.7%). The correlation between entry BW percent survival averaged over the five field trials and entry means from drench inoculation in the greenhouse was highly significant (r = 0.70), suggesting that the drench inoculation method is effective in selection for BW resistance.

Multilocation trials are important for breeding programs to identify high-yielding, adapted lines for a wide range of environments. In this study, we evaluated yield and yield components (fruit weight, fruit length, and fruit width) as well as days to 50% anthesis and fruit maturity of the 10 chili pepper lines in the International Chili Pepper Nursey 15 (ICPN15) distributed by the World Vegetable Center to interested cooperators worldwide. Performance data of the ICPN15 entries were received from collaborators evaluating the set in seven different environments in five countries (Indonesia, South Korea, Thailand, Taiwan, and Vietnam). Significant genotype-by-environment (G × E) interactions were detected for all traits evaluated. Additive main effect and multiplicative interaction analyses indicated high environmental influence on yield, days to 50% anthesis, and maturity, whereas genotype was the greatest contributor to variability in the market-driven yield components of fruit length, width, and weight. Four lines (ICPN15-4, -5, -7, and -10) were identified as highly stable and could serve as sources of yield and yield component stability in either short fruit market segments (ICPN15-4) or long fruit market segments (ICPN15-5, -7, and -10). We attempted to used publicly available weather data to help in explaining the source of the environmental variability; however, differences between analyzed and observed weather were too different to be useful. This is evidence that weather data should be collected at each testing environment in future studies. This study provides a basis for future studies in the stability of important horticultural traits in pepper, and highlights the need for further work in this area.

Tomato (Lycopersicon esculentum Mill.) is among the most widely consumed vegetables worldwide and an important source of certain antioxidants (AO) including lycopene, β-carotene, and vitamin C. Improvement of tomato for content of AO and overall antioxidant activity (AOA) could potentially benefit human health in many countries. We evaluated 50 L. esculentum and three L. pimpinellifolium (L.) Mill. entries for contents of lycopene, β-carotene, ascorbic acid, total phenolics, and two assays for antioxidant activity [anti-radical power (ARP) and inhibition of lipid peroxidation (ILP)] for 2 years during the same period in south Taiwan. We detected high levels of genetic diversity for the AO and AOA measured in this study. Group means of the L. pimpinellifolium entries were significantly higher than L. esculentum group means for ARP, ILP, lycopene, ascorbic acid, phenolics, and soluble solids concentration, suggesting that introgression of alleles from L. pimpinellifolium may have potential to improve cultivated tomato for these traits. Ranking of entries for ILP and ARP were consistent between years, particularly for those entries with the highest means and these assays could be adopted by tomato breeders. Results from ILP and ARP assays were highly correlated (r = 0.82^**) and it would be unnecessary to use both assays for tomato. Lycopene, β-carotene, ascorbic acid, soluble solids, and total phenolics were all positively correlated with ARP. Among AO, total phenolics content was most closely associated with ARP (r = 0.90^**) and ILP (r = 0.83^**); this suggests that phenolics make a major contribution to AOA in tomato fruit. Fruit size was negatively correlated with ARP (r = -0.74^**) and ILP (r = -0.71^**), indicating that combining large fruit size and high AOA will be challenging.

Amaranth (Amaranthus sp.) is an important leafy vegetable in Africa where most farmers grow unimproved landraces. Information about amaranth genetic diversity and its adaptation to different environments will help breeders develop improved commercial varieties that meet market requirements. The objectives of this study were to investigate the performances of amaranth entries for vegetable yield across locations and seasons, assess the relative contributions of genetic vs. environmental sources of variation to yield, and cluster locations into mega-environments (MEs) to suggest future test sites. Twenty-six diverse entries were evaluated for vegetable yields in replicated trials at five locations in wet-cool and hot-dry seasons in Tanzania. Season explained the highest proportion (52.1%) of the total sum of squares followed by entries (24.9%) and locations (23.0%). Mean yield across the hot-dry season trials (27.7 t·ha⁻¹) was 47.3% greater than the mean yield across wet-cool season trials (18.8 t·ha⁻¹). Differences among entries in vegetable yield were higher in the hot-dry season than in the wet-cool season, indicating that gain from selection is likely to be greater in the hot-dry season. Most entries performed well in either wet-cool or hot-dry season but a few entries were adapted to both seasons. Two MEs were identified, one characterized by lower altitudes, higher temperatures, and less fertile soils, and a second ME associated with higher altitudes, lower temperatures, and more fertile soils. Each ME may serve as an initial selection site for their respective target environment. Targeting a specific season may give a better chance of finding high-yielding varieties.

Tomato yellow leaf curl virus (TYLCV), a heterogeneous complex of whitefly-vectored geminiviruses, is a serious production constraint of tomato (Lycopersicon esculentum Mill.) in Asia, the Middle East, and the Americas. In this study we report on mapping of a DNA fragment introgressed into cultivated tomato presumably from the wild species L. hirsutum Humb. and Bonpl. and found to be associated with TYLCV resistance. To locate introgressions of wild tomato alleles in TYLCV-resistant tomato line H24, its DNA was digested with six restriction enzymes and probed with 90 RFLP markers evenly spaced throughout the genome. This polymorphism survey revealed the presence of one wild tomato introgression each on chromosomes 8 and 11. Plants of a F₂ cross between H24 and a susceptible tomato line were probed with randomly amplified polymorphic DNA (RFLP) markers linked to the targeted regions and F₃ families were developed by self-pollination of F₂ plants that carried none, one, or both introgressions in either homozygous or heterozygous states. Plants of F₃ families, parents, and control tomato line Ty52 (homozygous for the Ty-1 allele for TYLCV tolerance) were exposed to viruliferous whiteflies (Bemisia tabaci Gennadius) in greenhouses at the Asian Vegetable Research and Development Center, Taiwan, and the University of Agricultural Sciences, Bangalore, India. Results indicated that F₃ families homozygous for the introgression on chromosome 11 were resistant to TYLCV at both locations. Additional probing showed that the chromosome 11 introgression spanned markers TG36 to TG393, covering a distance of at least 14.6 centimorgans. This is the first report of TYLCV resistance in tomato mapped to chromosome 11.

Like everything for the past 2 centuries, agriculture has depended increasingly on fossil fuel energy. Pressures to shift to renewable energy and changes in the fossil fuel industry are set to massively alter the energy landscape over the next 30 years. Two near-certainties are increased overall prices and/or decreased stability of energy supplies. The impacts of these upheavals on specialty crop production and consumption are unknowable in detail but the grand lines of what will likely change can be foreseen. This foresight can guide the research, extension, and teaching needed to successfully navigate a future very unlike the recent past. Major variables that will influence outcomes include energy use in fertilizer manufacture, in farm operations, and in haulage to centers of consumption. Taking six increasingly popular fruit and vegetable crops and the top two horticultural production states as examples, here we use simple proxies for the energy requirements (in gigajoules per ton of produce) of fertilizer, farm operations, and truck transport from Florida or California to New York to compare the relative sizes of these requirements. Trucking from California is the largest energy requirement in all cases, and three times larger than from Florida. As these energy requirements themselves are all fairly fixed, but in future will likely rise in price and/or be subject to interruptions and shortages, this pilot study points to two commonsense inferences: First, that fruit and vegetable production and consumption are set to reposition to more local/regional and seasonal patterns due to increasing expenses associated with fuel, and second, that coast-to-coast produce shipment by truck will become increasingly expensive and difficult.

Habanero (Capsicum chinense Jacq.) is widely grown and consumed in West and Central African countries, and viral diseases represent an important production challenge. Diagnosis of the viral species affecting habanero productivity in Benin is limited, and understanding this will enable more efficient host resistance breeding. During 2019 and 2020, we characterized the incidence and severity of the viral diseases infecting nine promising habanero breeding lines and one commercial hybrid check under open field conditions in Benin. The horticultural performance, including yield and yield component traits of the entries, was determined during the 2 years of the experiment. A randomized complete block design was used with three replications, each with 24 plants. Data were recorded on days to 50% flowering and 50% fruit maturity, yield and on the yield components of fruit weight (g), fruit length (cm), and fruit width (mm), as well as disease incidence and severity. In total, 35 leaf samples were collected for viral diagnosis among habanero breeding lines. We found that Pepper veinal mottle virus (PVMV; Potyvirus) was the overwhelmingly predominant virus in our trials, with an 80% incidence; however, we found frequent coinfection of PVMV with Cucumber mosaic virus (CMV, Cucumovirus), Polerovirus, and, to a lesser extent, Chili veinal mottle virus (ChiVMV; Potyvirus). The mean disease incidence across all entries was 60%. AVPP1932 and PBC 2010 had the lowest disease incidence (35% and 43%, respectively), whereas AVPP1929 had the highest (86%) disease incidence. The F₁ hybrid check Afadja had the overall highest yield, with 30 t⋅ha⁻¹, followed by AVPP1932, with 19 t⋅ha⁻¹, both in 2019. There was a negative correlation between disease incidence and total yield (r = −0.44; P < 0.001), supporting previous studies indicating that viral diseases are major production constraints for habanero in West Africa. This study provides insight regarding the need to improve habanero for resistance to aphid-transmitted viruses and develop integrated pest management strategies to limit losses in Benin.