PRELIMINARY RESULTS REGARDING THE FRUIT QUALITY AND YIELD OF SOME BLUEBERRY GENOTYPES

Vaccinium corymbosum is one of the berry species with economic and food interest to Romanian growers and consumers. The development of blueberrty crop is a result of breeding activity, which has generated many cultivars of quality fruit and high productivity. The characters that are of economic interest in the cultivation of blueberries depend on the area of cultivation where the new cultivars are obtained. The study was conducted in summer 2020 in an experimental plot established in 2015 with seven blueberry genotypes, at Research Institute for Fruit Growing, Pitesti, Romania in the Small Fruit Laboratory, having an experience in the field of more than 40 years. The objective at this study is to compare some of fruit characteristics from genotypes 'Azur', 'Delicia', 'Duke', 'Northblue', 'Simultan', '4/6' and '6/38': plant yield, average fruit weight, fruit length, fruit diameter, the soluble solids, fruit acidity or pH, fruit firmness. During this study 'Delicia' cv. proved to have the highest production per plant (4.20 kg plant), the highest values of fruit diameter (19.70 mm), and the highest value of fruit total titratable acidity (01.25 %).

Development of a new method for determining the degree of ripeness of tomato fruits with different colors of ripe fruits

The paper evaluates the most common sensory, physical, physicochemical and biochemical methods of determining the degree of ripeness of tomato fruits. On the example of small-fruit varieties with red, orange, yellow and brown colors of ripe fruits, an attempt was made to create a universal scale to assess the degree of ripeness of tomato fruits based on the physiological state of the fruits. The paper presents data on the quantitative content of endogenous ethylene in fruits with certain ripeness level.

Features of the strawberry field repository formation

For the successful functioning of a breeding and nursery center of scientific and practical work with fruit and small fruit crops, an important task is to create repositories, including thosein the field. A field repository is a plant gene bank based in accordance with international standards on planting material that is free from dangerous pathogens, including viruses, representing tested for productivity typical plants.For the purpose of a comparative study of promising varieties, hybrids and clones-candidates for original plants, a field repository and mother plantation of strawberries clones and varieties have been created on the territory of the Federal Horticultural Research Center for Breeding, Agrotechnology and Nursery.As a result of research in 2015-2020, 386 high-yielding strawberry plants were selected and tested for the main harmful viruses using diagnostic kits from “Loewe” firm (Germany). The prevalence of harmful Arabis mosaic virus (ArMV), Raspberry ringspot virus (RpRSV), Tomato black ring virus (TBRV), Strawberry latent ringspot virus (SLRSV), Cucumber mosaic virus (CMV) in strawberry plantations depended on the area cultivation, varietal composition of plantings and ranged from 31 to 69 %. The prevalence of viruses RpRSV (up to 36 %), TBRV (up to 31 %) and CMV (up to 22 %) was established. The high efficiency of dry-air thermotherapy for the recovery of strawberries with the number of virus-free intact plants of 56 % has been shown.A genebank of "candidates for original plants" has been formed from 234 strawberry plants of 39 varieties and hybrids, which, after confirming their status by PCR, will be transferred to the category of "original plants".

Mobilization of fruit, small fruit and nut crop genetic resources in Belarus

Background. Natural populations of fruit and small fruit plants in Belarus and their specific and varietal composition for a long time attracted the attention of pomologists and breeders. Identification and mobilization of unique local forms and landraces as genetic sources of useful traits as well as monitoring duplicate collections will contribute to their more effective use in breeding practice to develop competitive domestic cultivars of various crops and reveal the adaptability of foreign cultivars to the conditions of Belarus.Methods. The itinerary of the collecting mission passed through 6 regions of the Republic of Belarus (Gomel, Minsk, Mogilev, Vitebsk, Brest, and Grodno) in 2012–2017.Results. As a result, 221 samples of fruit, small fruit and nut plants were collected, including 18 rootstocks of fruit crops. By 2021, 105 unique landraces were tested in the plant introduction and quarantine nursery and planted in the field gene bank, including 28 accessions of apple, 33 of pear, 11 of sour cherry, 5 of sweet cherry, 9 of plum, 8 of apricot, 1 of almond, 2 of hazel, 3 of garden strawberry, 1 of black chokeberry, 1 of viburnum, and 1 of bird cherry. There are plans to use the obtained accessions in breeding practice assources of valuable agronomic traits (high winter hardiness, high yield, resistance to a set of plant pathogens, etc.).

Investigating the Effect of Fruit Size on Ripening Recovery of Banana Treated with 1-Methylcyclopropene

Postharvest application of 1-methylcycloprepene (1-MCP) on banana fruit to extend shelf-life and maintain quality is inconsistent as treated fruit do not ripen uniformly. Banana response to 1-MCP treatment can be variable due to within-bunch variation in fruit size, composition, and maturity. Therefore, the present study investigated whether fruit size variation explains variability in ripening recovery. To investigate this relationship, large, medium, and small fruit were treated with 0 nL L−1 1-MCP (control), 400 nL L−1 1-MCP and 50 µL L−1 ethephon + 400 nL L−1 1-MCP. Fruit were then ripened using 800 µL L−1 ethephon and stored at 23 °C for 30 d. Irrespective of fruit size, treating banana with 1-MCP and ethephon + 1-MCP prolonged shelf-life by 30 d compared to control, which were fully ripe at 15 d for medium and large fruit, and 20 d for small fruit. 1-MCP significantly delayed yellow colour development (colour stage 4), chlorophyll degradation (97.4 µg/g), and sucrose (2.57 mg/g) and glucose (0.86 mg/g) accumulation in small compared to medium and large fruit. However, firmness (56.13 N) and starch (0.68 mg/g) were significantly lower in 1-MCP-treated small-sized fruit compared to medium and large fruit. Moisture loss was also significantly higher (19.49%) in 1-MCP-treated small fruit compared to medium (14.89%) and large (18.11%). Combined ethephon and 1-MCP allowed for an increase in ripening in small, medium, and large fruit. Overall, medium and large fruit treated with 1-MCP and ethephon + 1-MCP recovered their ripening capacity better compared to small fruit. The results demonstrate that 1-MCP efficacy is influenced by fruit size, whereas ethephon + 1-MCP treatment was consistent across small, medium, and large fruit. The effect of fruit size on 1-MCP efficacy might explain the inconsistency of the treatment in the banana fruit. Therefore, it is important to apply 1-MCP on fruit of approximately the same size to achieve the full benefit of the treatment. Moreover, fruit treated with 1-MCP + ethephon recovered their ripening capacity, irrespective of size, suggesting that it is a beneficial treatment.

A Novel Banana Mutant “RF 1” (Musa spp. ABB, Pisang Awak Subgroup) for Improved Agronomic Traits and Enhanced Cold Tolerance and Disease Resistance

Banana is a major fruit crop grown in tropical and subtropical regions worldwide. Among cultivars, “FenJiao, FJ” (Musa spp. ABB, Pisang Awak subgroup) is a popular variety of bananas, due to its better sugar-acid blend and relatively small fruit shape. However, because the traditional FJ variety grows relatively high in height, it is vulnerable to lodging and unsuitable for harvesting. In this study, we sought desirable banana mutants by carrying out ethyl methanesulfonate (EMS) mutagenesis with the FJ cultivar. After the FJ shoot tips had been treated with 0.8% (v/v) EMS for 4 h, we obtained a stably inherited mutant, here called “ReFen 1” (RF1), and also observed a semi-dwarfing phenotype. Compared with the wild type (FJ), this RF1 mutant featured consistently improved agronomic traits during 5-year field experiments conducted in three distinct locations in China. Notably, the RF1 plants showed significantly enhanced cold tolerance and Sigatoka disease resistance, mainly due to a substantially increased soluble content of sugar and greater starch accumulation along with reduced cellulose deposition. Therefore, this study not only demonstrated how a powerful genetic strategy can be used in fruit crop breeding but also provided insight into the identification of novel genes for agronomic trait improvement in bananas and beyond.

High Tunnel Production of Containerized Hybrid and Heirloom Tomatoes Using Grafted Plants with Two Types of Rootstocks

Tomatoes (Solanum lycopersicum) are not only one of the most widely grown and consumed vegetables in the U.S., but are also one of the most economically important vegetables for Mississippi growers operating on small- to medium-sized farms. High tunnel production and vegetable grafting serve as effective approaches to provide season extension and improve productivity and resistance to a number of abiotic and biotic factors for tomato plants. Six tomato cultivars, including three hybrids (‘Big Beef’, ‘Early Girl’, and ‘Sun Sugar’) and three heirlooms (‘Brandywine’, ‘Mortgage Lifter’, and ‘San Marzano’), were evaluated for plant growth, fruit yield, and quality in a containerized high tunnel production system in 2020. Each cultivar was grafted onto two types of interspecific hybrid rootstocks ‘Emperador’, or ‘Maxifort’, or grown non-grafted as control. ‘Big Beef’ and ‘Early Girl’ produced comparable highest marketable yields of 9.62 to 11.12 kg per plant, compared with ‘San Marzano’ and ‘Sun Sugar’ producing the lowest marketable yields of 3.27 to 4.76 kg per plant due to small fruit sizes. Grafting the selected tomato cultivars with the two rootstock types did not alter total marketable yield of any cultivar, but affected overall stem diameter, fruit color, and β-carotene concentrations. The rootstock ‘Emperador’ decreased soluble solids content and titratable acidity in ‘Early Girl’ compared to ‘Maxifort’ grafted or non-grafted plants. The high tunnel enabled early transplanting and resulted in advanced tomato harvest by approximately three to four weeks compared to local field production.

Detection of Fruit Meals Within Laboratory-Raised and Field-Trapped Adult Drosophila suzukii (Diptera: Drosophilidae) Guts

The feeding habits of adult Brachycera are understudied and may provide important context for understanding invasive pest biology, as with the polyphagous small fruit pest Drosophila suzukii. We developed molecular methods to study adult D. suzukii gut content in order to understand its feeding habits. We designed and verified two primer pairs specific for either blueberries or blackberries and used a qPCR melt curve analysis to determine whether we can detect the presence or absence of berry feeding by adult flies. In a laboratory assay, the blueberry fly meal DNA can be detected for longer periods than the blackberry meal DNA. Generally, female gut contents are less variable than male gut contents. We also tested recently emerged flies that were not fed as adults but developed as larvae in either blueberries or blackberries. Some adult flies from each fruit had detectable fruit DNA in their gut, which could be due to pupal meconium feeding after emergence. Next, we aimed to test the primers in the field to develop techniques to track fruit feeding by D. suzukii in its natural field environment. First, to identify the most appropriate collection method, we determined how long we could detect fruit DNA, using previously developed primers within D. suzukii gut preserved in four types of trap fluid in the laboratory. The likelihood of detecting blackberry DNA differed by day, trap fluid, and between sexes. For the blueberry primer, the possibility of detecting blueberry DNA differed by trap fluid only. Based on those results, we used RV antifreeze with a Scentry SWD lure in field trials at two research station locations, one containing blackberries and one with blueberries. We established transects away from each fruit planting and collected up to 120 total flies at each point along transects. There were no significant differences in the number of flies containing berry DNA among collection points along the transect in both locations. These results suggest that adult flies move between crop and non-crop habitats and may not be highly dependent on fruit food resources.