Horticultural Characteristics Research Articles

Screening Subtropical Lettuce Accessions for Heat Tolerance by Incorporating Accelerated Shelf Life Testing

Lettuce (Lactuca sativa L.) is grown worldwide, from temperate to subtropical climates. Spring season production in humid, subtropical regions, such as southern Florida, is characterized by rising ambient temperatures that can stress lettuce to prematurely bolt and lose shelf life. The objectives of this research were 1) to identify genetic variability in heat tolerance and shelf life among lettuce types and accessions grown under humid, subtropical conditions, and 2) to understand the genotype × environment (G × E) interaction to estimate shelf life of these lettuce accessions. Five lettuce types (romaine, crisphead, butterhead, leaf, and Latin) were grown under commercial conditions in the Everglades Agricultural Area near Belle Glade, FL, USA, for five field experiments over two seasons. Lettuce heads were evaluated at harvest, and subsets were transported to a local commercial grower/shipper for vacuum-cooling and storage at 15 °C according to previously determined protocols for accelerated shelf life testing. Visual appearance ratings were made across harvests and storage time points to segregate lettuce accessions with an estimated marketable shelf life >14 days. The breeding lines tested in this research had head weight and marketability comparable to commercial cultivars. Notably, the crisphead accessions 50113, 60157, 60159, and H1098 had the highest estimated and actual shelf life of more than 21 days, with no presence of bolting or tipburn. Meanwhile, romaine, butterhead, leaf, and Latin types had accessions with estimated and actual shelf life ranging from 14 to 28 days and no presence of bolting or tipburn. A G × E analysis indicated that this interaction is significant; therefore, breeders should consider analyzing G × E when developing new cultivars with good horticultural characteristics, longer shelf life, and most importantly, adaptation to warmer humid, subtropical conditions.

Evaluation of Select Monarda Taxa in Montane and Piedmont Regions of Georgia: I. Horticultural Performance and Disease Tolerance

We evaluated several horticultural cultivars and species of Monarda, a genus native to North America with a center of diversity in the Southeast and advertised as beneficial to wildlife, to assess landscape performance with respect to vegetative habit, flower production, and disease tolerance in Georgia Piedmont and montane habitats. We established two experimental sites: the State Botanical Garden of Georgia in Athens (USDA Zone 8b) and the Georgia Mountain Education and Research Center in Blairsville (USDA Zone 7b). We then tracked plant performance over 2 years after establishment. Our study included 10 samples of Monarda, representing five cultivars and four species. Estimated height and width at flowering showed M. bradburiana, M. Sugar Buzz® Grape Gumball, and the M. punctata ecotypes were smaller than other tested taxa. M. fistulosa had the most flowers at the Blairsville site and equal flowering with M. punctata at the Athens location, but most taxa flowered for 2 to 3 months with ∼100 flowering stems per stand. All samples were susceptible to powdery mildew, but M. bradburiana displayed the highest level of tolerance. Otherwise, cultivars tended to be more tolerant to powdery mildew than species. The observed variations in horticultural characteristics and performance highlight the high value of this genus for Georgia landscapes.

Soil Nitrogen Fertility Influences the Growth and Yield of American Elderberry but Is Less Impactful than Genotype and Environment on Other Horticultural Characteristics

A long-term horticultural experiment was conducted at two geographically distinct sites in southern Missouri in 2011–15 to study the response of American elderberry [Sambucus nigra (L.) subsp. canadensis (L.) Bolli] to various soil nitrogen (N) fertilizer levels. Three commercially available elderberry cultivars (‘Adams II’, ‘Bob Gordon’, and ‘Wyldewood’) were used. The three cultivars were each assigned to 16 of 48 four-plant plots in a completely randomized manner at each site. Four replications of four N fertilizer treatments (0, 56, 112, 169 kg⋅ha−1 N) were randomly assigned to each cultivar’s plots and applied for 4 years (2012–15). Fruit yields, plant growth, phenology, and pest incidence were determined each year. Fruit quality was assessed by analyzing basic juice characteristics as well as organic acids, carbohydrates, anthocyanins, and polyphenols from 2012–14 samples. Leaf tissue analysis determined the plants’ mineral contents in 2012–14. Most factors evaluated were significantly affected by site, year, and cultivar, whereas the effects of N fertilizer treatment were less definitive. Fruit yields and plant growth increased with increasing N levels. For example, plants fertilized with 0, 56, 112, and 169 kg⋅ha−1 N produced 123, 137, 155, and 161 fruiting cymes per plot (5.8 m2), respectively. The eriophyid mite incidence was higher on fertilized plants, but other pests were not influenced by the N treatment. Basic fruit juice characteristics (soluble solids, pH, titratable acidity, polyphenols) were not influenced by the N treatment, whereas total anthocyanins were statistically higher in unfertilized plants. Levels of organic acids and carbohydrates in juice varied statistically among N treatments, but patterns were difficult to discern. Leaf N concentrations were correlated with N fertilizer levels—2.75% N with the highest fertilizer level compared with 2.55% N in unfertilized plants. Leaf levels of most other macronutrients varied, but consistent patterns did not emerge, and none of the micronutrients was different among N treatments. Although elderberry plants responded positively to increased N fertilizer levels in terms of plant growth and fruit yield, genetics (cultivar) and environment (site, year) were more influential on most other experimental factors evaluated.

Screening and classification of rosehip (Rosa canina L.) genotypes based on horticultural characteristics

BackgroundDuring the pandemic, the interest in colorful wild small fruits increased due to their positive effects on health. Also it has become very important to offer species with high nutritional value as fresh or processed products for human consumption due to increasing world population and decreasing arable land. In this context, we characterized the horticultural characteristics of 11 rosehip genotypes grown from seeds.ResultsCitric acid was determined as the main organic acid in all the genotypes investigated. The mean values of the organic acids obtained from all the genotypes were found to be as follows: citric acid (7177 mg L–1), malic acid (3669 mg L–1), tartaric acid (1834 mg L–1), oxalic acid (1258 mg L–1), carboxylic acid (631.9 mg L–1), shikimic acid (157.8 mg L–1), ascorbic acid (155 mg L–1), and acetic acid (20.9 mg L–1). Ellagic acid was the dominant phenolic compound (90.1 mg L–1 – 96.2 mg L–1) in all genotypes. The average values obtained from all genotypes for total phenolics, total flavonoids, and antioxidant activity were 37 261 mg GAE L–1, 526.2 mg quercetin L–1, and 93.6%, respectively. These characteristics had the lowest coefficients of variation, which indicated that all genotypes were similar regarding high biochemical with antioxidant effect. In addition, fruit width, fruit length, and fruit weight varied between 13.0 and 17.3 mm, 20.7 and 25.5 mm, and 1.4 and 2.7 g, respectively.ConclusionsThe genotypes were categorized according to different purposes, such as suitability for wine production, making vinegar, etc. While the pomological characteristics were strongly positively correlated among themselves, they were generally found to be negatively correlated with the phytochemical characteristics. Categorizing genotypes according to different usage purposes can improve the agricultural and industrial application of rosehip and enhance their breeding efficacy.

Morphological and horticultural characteristics of some commercial banana (Musa spp.) cultivars of Kerala

Morphological and horticultural characteristics of some commercial banana (Musa spp.) cultivars of Kerala

Breeding Lettuce for Resistance against Sclerotinia minor

Lettuce drop caused by Sclerotinia minor is a damaging disease of romaine lettuce (Lactuca sativa L.) production in California. Introgression of partial resistance from wild, primitive, or heirloom accessions into modern cultivars could improve integrated management approaches to the disease. Breeding methods for lettuce drop resistance are not well developed and hinder the development of new lettuce drop–resistant cultivars. The objective of this work was to develop a pedigree-based breeding method for introgression of lettuce drop resistance into modern romaine germplasm. Progeny from crosses between the partially resistant cultivar Eruption and the susceptible romaine cultivars Darkland and Hearts Delight were selected in a modified pedigree breeding scheme. Families were evaluated for disease incidence and selected for lettuce drop resistance in artificially infested field experiments conducted in the summer and fall. Infected plants of partially resistant lines commonly do not produce seed, and therefore selection of resistant plants from infested nurseries is not possible. Noninfested field experiments were used to select individual plants with improved horticultural characteristics for seed production, but from within resistant families only. Evaluation and selection of progeny using this breeding scheme occurred from the F2:3 through the F5:6 generations. In all generations, superior resistance was identified in the ‘Eruption’ × romaine crosses. The breeding scheme generated eight green romaine-type inbred lines with better resistance than the romaine parent and better head weight than ‘Eruption’. Use of the new romaine lines as parents in backcrosses to romaine produced F2:3 families with high levels of resistance. The pedigree method used in this research can be implemented with any source of resistance, but is constrained by the use of family selection and the inability to select individual plants for resistance directly. Breeding schemes that use single seed descent or molecular markers are alternative approaches that would enable selection for resistance on individual genotypes.

Mainstreaming production and nutrient resilience of vegetable crops in megacities: pre-breeding for terrace cultivation.

Modern megacities offer convenient lifestyles to their citizens. However, agriculture is becoming increasingly vulnerable, especially during unexpected public health emergencies such as pandemics. Fortunately, the adaptability of terrace vegetables cultivation presents an opportunity to grow horticultural crops in residential spaces, bringing numerous benefits to citizens, including enhanced nutrition and recreational engagement in the cultivation process. Although certain planting skills and equipment have been developed, the citizens tend to sow some seeds with unknown pedigree, it is rare to find new plant varieties specifically bred for cultivation as terrace vegetables. To expand the genetic basis of new breeding materials, elite parents, and varieties (pre-breeding) for terrace cultivation, this review not only discusses the molecular breeding strategy for the identification, creation, and application of rational alleles for improving horticultural characteristics including plant architecture, flavor quality, and ornamental character, but also assesses the potential for terrace cultivation of some representative vegetable crops. We conclude that the process of pre-breeding specifically for terrace cultivation environments is vital for generating a genetic basis for urban terrace vegetable crops.

APETALOID AND PETALOID FEMALE PERFORMANCE ON HORTICULTURAL CHARACTERISTICS OF F1 AMERICAN MARIGOLD (TAGETES ERECTA L.) HYBRIDS

This research’s objectives focused on using two male-sterile systems, apetaloid and petaloid types, as female parents for the F1 marigold cut flower hybrid development. These female lines’ creation came from the same original line, the gynomonoecious line, with five backcrosses to obtain two female lines, FY1502 and FY1502AP. Their crossing with 10 male lines progressed during the summer from April to August 2016. Then, growing the progenies of 20 crosses and four commercial varieties as checks for characterization and evaluation continued in a lattice design with two replications. Planting them in six blocks contained 10 plants per treatment. The data recorded on eight horticultural characteristics include flower diameter, number of petals per flower, calyx length, peduncle length, flower weight, the number of days from sowing to first flowering, plant height, and plant bush diameter, as well as, the morphology of flowers. The results showed that progenies from two female apetaloid and petaloid with the same male line gave similar outcomes; all progenies produced male sterile double-flowers with golden-yellow flowers, except progenies of MY1501 and MY1502, which created yellow flowers. FY1502 gave the same superior F1 progenies as FY1502AP in the diameter of the flower. Based on the results, both females could give good characteristics on flower diameter, calyx length, plant height and bush diameter, and early flowering. However, the heterobeltiosis of the F1 progenies of a few vegetative and reproductive characteristics differed. The FY1502AP gave better progenies in peduncle length heterobeltiosis than those of FY1502 and slightly better for plant bush diameter, whereas FY1502 gave slightly better in flower weight heterobeltiosis than those of FY1502AP. The findings of this study indicate that this apetaloid type could benefit Thailand’s marigold seed production program.

Correlation and path analysis studies in onion (Allium cepa) genotypes

The present study was carried out at the experimental farm of the Department of Vegetable Sciences, Dr. YashwantSingh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh during the winter (rabi) season of 2019–20 and 2020–21 to study the genetic variability, correlation and path studies in 30 different genotypes of the onion (Allium cepa L.) crop. All genotypes reflected a wide and significant spectrum of variability for all the traits under study. Genotypes UHF-ONI-13, UHF-ONI-15 and UHF-ONI-16 outperformed other genotypes in terms of yield and other critical horticultural characteristics. The magnitude of phenotypic coefficient of variation was higher than the genotypic coefficient of variation for all the characters. The phenotypic and genotypic coefficients of variability were high for doubles/deformed bulbs, moderate for leaf length, plant height, average bulb weight, bulb yield per plot and per hectare. High heritability along with high to moderate genetic gain was observed for doubles/deformed bulbs, leaf length, plant height, average bulb weight, bulb yield per plot and bulb yield per hectare, which suggested that improvement can be achieved through simple selection. Bulb yield had significant and positive correlation with average bulb weight, equatorial diameter, plant height, polar diameter, days to harvest and days to 50% neck fall. Path analysis showed that bulb weight, equatorial diameter, bulb shape index, neck thickness, total soluble solids, plant height and leaf length had a positive direct effect on bulb yield.

Development of male sterile lines of CMS chilies (Capsicum annuum L.) from F1 hybrids.

Selfing and crossing methods were used to develop the cytoplasmic male sterility (CMS) lines from 2 elite F1 hybrids of CMS hot chilies. The pungency of the CMS lines was improved by backcrossing with the B cultivar. The first and second backcrossed progenies of the CMS lines showed significantly higher capsaicin contents than the F1 hybrids. One good female line K16 × BBC2 (K16), was selected and backcrossed with 3 good maintainer cultivars, C5, C9 and C0. Some incomplete male sterility of pollens was demonstrated in the F1 hybrids and the 1st backcrossed progenies while the partial sterility disappeared by the stage of the second and third generations of backcrossing. When K16 and P32 were crossed with restorers, fruit yields and yield components of certain F1 hybrids, parental lines and commercial varieties were significantly different. Heterosis of yield and yield components of the F1 hybrid chilies was significant. When K16 was used as a female parent, positive and significant heterosis of the F1 hybrids was the same as P32. Moreover, significant GCA of the restorer lines, C7, C8 and C9, was observed in some horticultural characteristics. Furthermore, significant differences of the specific combining ability of some characteristics were observed in a few F1 hybrids.

Lettuce (Lactuca sativa L. var. Rincon) Production Using Organic Nutrient Solution under Hydroponics System

Lettuce is one of the most widely hydroponically grown crops and studies showed that lettuce has a high yield and good quality under a soilless production. However, the nutrient solution used in hydroponic systems is based on chemical fertilizers and recently, there has been an increased interest in organic hydroponics as the market for organic food continues to grow. The study was conducted to evaluate commercially available organic nutrient solutions (Vermitea, BioVoltin, Ramils, Healthynest) in comparison to conventional inorganic fertilizers (Snap) in hydroponic lettuce production with water as a negative control. The crop experiment was carried out in a plastic polyhouse with a mesh net at the Institute of Agriculture, Camiguin Polytechnic State College – Catarman Campus, Tangaro, Catarman, Camiguin, from November 1, 2021, to December 15, 2021, using a Randomized Complete Blocked Design with three replications. Results of the study showed that among organic nutrient solutions, Treatment 5 (Ramils) and Treatment 7 (Healthynest,), showed comparable results to conventional inorganic fertilizer, Treatment 1 (Snap) in terms of horticultural characteristics, root development, survival rate, yield, and sensory quality attributes and cost and return analysis. However, different organic nutrient solutions exhibited no significant effects on nutrient solution consumption per plant and total nutrient solution consumption. Treatment 5 (Ramils) was considered best overall in terms of sensory quality attributes, overall acceptability and overall marketability except for color, succulence, and bitterness, followed by T1 and T7. Also, Treatment 5 (Ramils) and Treatment 7 (Healthynest) have the highest yield, hence generating the highest net returns, net profit margin, and return on investment.

Breeding Leucospermum for improved horticultural characteristics, disease tolerance and cultivation in tropical climates

Breeding <i>Leucospermum</i> for improved horticultural characteristics, disease tolerance and cultivation in tropical climates

Late-Season Sweet Orange Selections Under Huanglongbing and Citrus Canker Endemic Conditions in the Brazilian Humid Subtropical Region.

The Brazilian citrus orchards are comprised by few genotypes, which increases the risk of pest and disease outbreaks. The diversification of sweet oranges (Citrus × sinensis) in orchards also generates off-season revenue and extend the fruit processing period. This study aimed to evaluate several horticultural traits of 19 late-season sweet orange selections under citrus canker and huanglongbing (HLB) endemic condition in northwestern Paraná state, Brazil, in a long-term field experiment. Tree size, yield, fruit quality for fresh fruit and industrial markets, estimates of tree density and yield, and citrus canker and huanglongbing (HLB) incidences were assessed. The experimental design was a randomized block with three replicates and five trees per unit. The orchard was drip-irrigated and arranged at tree spacing of 6.5 m × 4.5 m. All scions were graft-compatible with Rangpur lime (C. × limonia). Valencia selections had the tallest trees and largest canopies, particularly Olinda, Frost and #121 with heights and volumes greater than 4.20 m and 43 m3, respectively. Natal África do Sul and Whit’s Late Valencia trees were the most productive with cumulative yields above 640 kg per tree. Most of the selections produced fruits of excellent physicochemical quality attending the fresh fruit and industrial market requirements. All selections showed similar horticultural characteristics for the fresh market, while Natal África do Sul and Charmute de Brotas were more suitable for juice processing. Frost Valencia and Valencia Late Fla. had the highest incidence of citrus canker on fruits (>20%), whereas IPR Folha Murcha, Charmute de Brotas and some Valencia selections (Chafeei Late, Campbell 479, Campbell 294, Olinda, Mutação and Whit’s Late) exihibed low incidence (3.0–17.7%). At 9 years, Valencia Mutação trees had high HLB incidence (93%). In contrast, Natal IAC and Folha Murcha IAC showed the lowest HLB incidence (13%). Our results revealed that Natal IAC, Folha Murcha IAC, IPR Folha Murcha, Natal Murcha, Campbell 479 Valencia and Valencia Late Fla. had the best horticultural performance in addition to low HLB incidence. Together, these late-season sweet oranges are the most advantageous selections for citrus orchard diversification under citrus canker and HLB endemic conditions in humid subtropical regions.

Screening of Naturally Grown European Cranberrybush (Viburnum opulus L.) Genotypes Based on Physico-Chemical Characteristics.

It has become very important to offer species with high nutritional value as fresh or processed products for human consumption in their daily diet for balanced nutrition. In the scope of this study, 15 naturally grown European Cranberry bush (ECB) genotypes that naturally grown were characterized in terms of horticultural characteristics. Fruit length, fruit width, fruit weight, the number of fruits per each cluster and cluster weight were determined within the ranges of 8.78–10.96 mm, 7.93–10.84 mm, 0.21–0.70 g, 31–121, and 7.70–66.67 g, respectively. Ranking of the average values of examined organic acids obtained from all genotypes found as; malic acid (11,419 mg L−1) > citric acid (1926 mg L−1) > ascorbic acid (581 mg L−1) > oxalic acid (561 mg L−1). Total phenolic content (TPC) and total flavonoid content (TFC) were found at high levels in ECB with 2922–3475 mg gallic acid equivalent (GAE) L−1 and 1463–3163 mg quercetin equivalents (QE) L−1, respectively. While pomological characteristics were found to be highly positive correlated with each other, they were negatively correlated with chemical properties. Low pH was found to be an important parameter to obtain higher amounts of phytochemicals such as TPC, TFC, organic and phenolic acids correlated with strong antioxidant effects. The obtained results will be useful for both germplasm enrichment and cultivation.

Triterpene Content in Flesh and Peel of Apples Grown on Different Rootstocks.

Advancements in rootstock breeding and selection have revolutionized the manner in which apples are grown throughout the world. Fruit tree breeding has typically focused on key horticultural characteristics. Even though agents with health benefits have been investigated more frequently during the recent years, information about the effect of different cultivation factors, such as the rootstock, on triterpene concentration is still lacking. The present study aimed to evaluate triterpene profiles and the quantitative composition of different parts of apple fruit that was grown on 17 various origin and vigor rootstocks. HPLC analyses of triterpenes in apple samples were performed. The highest total content of triterpenes (7.72 ± 0.39 mg/g) was found in peel samples of apples grown on the dwarf rootstock 62-396-B10®. Depending on the rootstock, apple peel samples accumulated 3.52 to 4.74 times more triterpene compounds than apple flesh samples. Ursolic acid was the predominant triterpene compound in apple peel and flesh samples. The highest content of ursolic acid (5.84 ± 0.29 mg/g) was found in peel samples of apples grown on the dwarf rootstock 62-396-B10®. Meanwhile, the lowest amount of ursolic acid (3.25 ± 0.16 mg/g) was found in apple peel samples grown on the dwarf rootstock Cepiland-Pajam®2. A proper match of a cultivar and a rootstock can program a fruit tree to grow larger amounts of higher quality, antioxidant-rich, and high-nutrition-value fruit.

Horticultural Characteristics of Summer Apple Cultivars from Turkey

Early varieties with a short active vegetation period are not exposed to abiotic stress factors for instance drought, high temperature, etc., caused by global climate change, and biotic stress factors such as codling moth (Cydia pomonella) and apple scab (Venturia inequalis) that cause serious economic losses. Therefore, their places are extremely important regarding sustainable, economical and quality production. In this context, four early varieties of apple (‘Vista Bella’, ‘Summer Red’, ‘Williams Pride’ and ‘Jersey Mac’) grown in Eskisehir—Turkey where has continental climate were characterized in terms of horticultural characteristics. The difference observed in flowering and harvest times between years showed that average air temperatures are essential on phenological characteristics. Furthermore, high temperature accelerates development physiology of fruit. Major important characteristics, namely, fruit length, width, weight, soluble solid content, antioxidant activity, vitamin C and total phenolic content were found in the range of 39.19–50.88 mm, 51.48–60.81 mm, 80.59–86.16 g, 11.87–12.19%, 50.69–80.57%, 2.24–4.79 mg 100 mL−1 and 259.23–871.42 mg GAE (gallic acid equivalent) L−1, respectively. ‘Summer Red’ and ‘Williams Pride’ varieties were found to be good in terms of pomological characteristics, while ‘Vista Bella’ came to the fore with its chemical properties. On the other hand, ‘Jersey Mac’ has shown superior performance in terms of both pomological and chemical characteristics. Pomological characteristics are affected more by ecological differences, while chemical characteristics vary according to the changes in the pomological properties. Pomological characteristics were found to have a significant positive correlation with each other but negatively correlated with chemical characteristics.

Morphological and horticultural characteristics of some commercial banana (Musa spp.) cultivars of Kerala

Morphological and horticultural characteristics of six cultivars of banana fruits (Musa spp.) that are commercially grown in Kerala, belonging to different genomic groups viz. Nendran (AAB), Pisang Lilin (AA), Karpooravalli (ABB), Njalipoovan (AB), Grand Naine (ABB) and Yangambi (KM-5) (AAA) were evaluated. The morphological traits were characterized using Banana Descriptors established by IPGRI (1996), from which 9 characters were selected for quantitative analysis. Horticultural characters on variables such as number of fruits per bunch, fruit length (cm), fruit pedicel length (mm), fruit pedicel width (mm), peel thickness (mm), pulp weight (g), fruit to peel ratio, fruit flesh firmness (cm2kg-1) were analysed and subjected to one way ANOVA to determine the significance (p=.05). The cultivar Nendran (AAB) exhibited large morphological and horticultural traits, particularly for the fruit length (22.07cm), pulp weight (89.20g) and peel weight (49.30g). The cultivar Karpooravalli (ABB) was smaller in terms of the fruit length (10.67 cm) and peel weight (9.65g), but had a large (4.81) fruit: pulp ratio compared to other cultivars studied. The present work reveals substantial morphological and horticultural variation among banana cultivars of different genomic groups, with an overlap of similarities and differences even in banana cultivars having the same genomic group.

Effect of Colchicine on Induction of Ploidy and Other Morphological Features of Different Crops: A Review

Colchicine is a mitotic inhibitor and it has been used for induction of tetraploids in different crops. Different concentration of colchicine has been used for different time period in vivo and in vitro. Colchicine is used for such purposes because rate of spontaneously doubling in most species is rare in tissue culture. Treatment of colchicine in in vitro culture plant tissues has been efficiently used to artificially produce polyploids in different plants. In different crops such as vegetables, fruits and flowers tetraploids produce variants with favourable horticultural characteristics like high yield, large fruit size and resistance to different environmental stresses. Tetraploids was induced in vivo by applying colchicine in an aqueous solution, lanolin paste, on apical shoot meristem of seedling and soaked seeds. Colchicine use has been found a very prosperous methodology for genome doubling in a lot of species.

Development and evaluation of hybrids resistant to late blight and leaf curl virus diseases in tomato

The current study in tomato (Solanum lycopersicum L.) was conducted at PAU, Ludhiana with the objective of developing hybrids possessing combined resistance to late blight and leaf curl virus diseases along with desirable horticultural characteristics. The experimental material which included 32 F1 hybrids (developed by line ? tester method), 12 parental lines (8 lines and 4 testers; including susceptible check Punjab Chhuhara) and standard check NS-524 were all planted in randomized complete block design with three replications. The values of ?2SCA/?2GCA were more than unity for all the traits except average fruit weight and ascorbic acid content, indicating the predominance of non-additive gene effects. Cross combinations CLN-154 ? LBR-12 and CLN-154 ? LBR-21 recorded significant heterosis over better parent and check for fruit yield and other quality characteristics. Artificial and natural screening was performed for all the experimental material against late blight and leaf curl virus diseases respectively. Out of 32 hybrids, crosses namely CLN-154? LBR-12, CLN-154 ? LBR-21, PVB-1 ? LBR-10, PVB-4 ? LBR-12 and CLN-104 ? LBR-10 were identified for combined disease resistance against late blight and leaf curl virus, in relation to desirable horticultural characteristics particularly fruit yield, average fruit weight, pericarp thickness, dry matter, titrable acidity and ascorbic acid content with fair amount of heterosis. Hence, the hybrids which displayed good potential in yield with acceptable performance of qualitative traits, along with combined disease resistance could be utilized for commercial exploitation.

Rootstock-Dependent Response of Hass Avocado to Salt Stress.

Salt stress is a major limiting factor in avocado (Persea americana) cultivation, exacerbated by global trends towards scarcity of high-quality water for irrigation. Israeli avocado orchards have been irrigated with relatively high-salinity recycled municipal wastewater for over three decades, over which time rootstocks were selected for salt-tolerance. This study’s objective was to evaluate the physiological salt response of avocado as a function of the rootstock. We irrigated fruit-bearing ‘Hass’ trees grafted on 20 different local and introduced rootstocks with water high in salts (electrical conductivity of 1.4–1.5 dS/m). The selected rootstocks represent a wide range of genetic backgrounds, propagation methods, and horticultural characteristics. We investigated tree physiology and development during two years of salt exposure by measuring Cl and Na leaf concentrations, leaf osmolality, visible damages, trunk circumference, LAI, CO2 assimilation, stomatal conductance, spectral reflectance, stem water potential, trichomes density, and yield. We found a significant effect of the rootstocks on stress indicators, vegetative and reproductive development, leaf morphogenesis and photosynthesis rates. The most salt-sensitive rootstocks were VC 840, Dusa, and VC 802, while the least sensitive were VC 159, VC 140, and VC 152. We conclude that the rootstock strongly influences avocado tree response to salinity exposure in terms of physiology, anatomy, and development.