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Chiwon W. Lee

Velvet flower (Salpiglossis sinuata, Solanaceae) can be used as an excellent demonstration plant for horticultural crop breeding classes. Salpiglossis produces large trumpetlike flowers exhibiting an assortment of corolla colors and pigmentation patterns. The pistil is large (3 to 4 cm or 1.2 to 1.6 inches long) with a sticky stigmatal tip and flowers can be easily emasculated prior to anthesis. The large pollen grains are shed in tetrads which can be separated and placed on the stigmatal surface. It takes eight to nine weeks from seeding to blooming, with a prolific flowering cycle that comes in flushes. Numerous seeds (about 750 per capsule) are obtained in three weeks after self- or cross-pollination. The influences of three genes that control flower color and pigmentation pattern can be conveniently demonstrated with their dominant and recessive alleles. The R gene controls flower color with red (RR or Rr) being dominant over yellow (rr). The D gene controls the density of pigmentation with solid (DD or Dd) color being dominant over dilute (dd) color. Corolla color striping is controlled by the St gene with striped (stst) being recessive to nonstriped (StSt or Stst) pattern. By using diploid lines of genotypes RRDD (red, solid), RRdd (red, dilute), or rrdd (yellow, dilute) and their crosses, students can easily observe a dominant phenotypic expression in the F1 hybrid and the digenic 9:3:3:1 segregation ratio in the F2 progeny. Another gene (C) that controls flower opening can also be used to show its influence on cleistogamous (closed, selfpollinated, CC or Cc) versus normal chasmogamous (open-pollinated, cc) corolla development. In addition, the induction and use of polyploid (4x) plants in plant breeding can also be demonstrated using this species.

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Heidi A. Kratsch

Alnusmaritima may have potential for use in home and commercial landscapes in northern Utah. This fast-growing, fall-blooming shrub is cold-hardy to USDA hardiness zone 3b and tolerant of nutrient-poor soils and full sun. Because this taxon is native to low-elevation wetlands, I seek to determine its response to the high desert soils and climate of northern Utah. My specific objective was to test germination and survival of plants from seed sowed in three diverse soil types typical of the Wasatch front in north-central Utah. Seeds were rinsed with distilled water and cold-stratified in darkness for 16 weeks between wet filter paper in sealed petri dishes. Stratified seeds were sowed in flats filled with soil from each of three sites at the Utah Botanical Center in Kaysville and held in a greenhouse. Seeds planted in flats filled with soilless germination mix served as controls. Flats with 60 seeds were experimental units, and each medium was replicated three times. Soils ranged from silty loam to loam, nitrate-N was 3.2 to 5.4 mg·kg-1, and there was 1.4% to 2.9% organic matter. Germination rates were highest in the soilless mix (50%). Of the three soil types, the highest germination rates (24%) occurred in a loamy soil high in organic matter (2.9%). Rates were similar (12.5% and 13%) in the other two soils. Seeds of A. maritima can germinate in soils typical of urban landscapes in northern Utah, so both the potential for invasiveness and the performance of plants in the landscape of northern Utah are being evaluated.

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R.E. Moran, S.M. Southwick, K.G. Weis, and B. Lampinen

Secondary or “rat-tail” bloom, a major site for fireblight infection of `Bartlett' pear, comprised 10% of the total bloom in 1997 and 20% in 1998. We are striving to find production practices that can be economically applied to reduce the number of “rat-tails.” Of the five known types of secondary clusters in pear, four occur on `Bartlett', the most numerous being types I and V. Type I rat-tails occur on the bourse at the base of normal clusters and bloom from 10 to 30 days after normal bloom. Type V rat-tails occur mostly at pruning sites and have one to three flowers per cluster, blooming 20 to 50 days after normal bloom. GA 3 or GA4+7 + BA were applied at 100 mg•L-1 in 1997 to reduce rat-tail bloom in 1998. In 1998, neither GA3 nor GA4+7 + BA had an effect on normal bloom or type I rattails. GA3 reduced type V rat-tails when applied at either 2 June, 2 July, or 15 Aug. but had no effect on type V clusters when applied at full bloom, petal fall, 16 June, or 15 July. GA4+7 + BA reduced the number of type V rat-tails when applied at either 2 June, 16 June, 2 July, and 15 July but had no effect when applied at full bloom, petal fall, or 15 Aug. Dormant pruning horizontal shoots resulted in as many rat-tails as vertical shoots, and heading cuts a similar number as stubbing cuts. Dormant pruning 1-year wood resulted in fewer rat-tails than 2-year wood. Summer pruning 21 or 49 days after bloom resulted in fewer rat-tails than pruning 10 days after harvest, but was similar to pruning 89 days after bloom. These and other results from ongoing work will be presented toward development of an integrated fire blight reduction strategy.

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Yin-Tung Wang and Lori L. Gregg

Bare-root seedling plants of a white-flowered Phalaenopsis hybrid [P. arnabilis (L.) Blume × P. Mount Kaala `Elegance'] were grown in five potting media under three fertility levels (0.25, 0.5, and 1.0 g·liter-1) from a 20N-8.6P-16.6K soluble fertilizer applied at every irrigation. The five media included 1) 1 perlite:1 Metro Mix 250:1 charcoal (by volume); 2)2 perlite:2 composted pine bark:1 vermiculite; 3) composted pine bark; 4) 3 perlite:3 Metro Mix 250:1 charcoal; and 5) 1 perlite:1 rockwool. During the first flowering season, plants in the 1 perlite: 1 Metro Mix 250:1 charcoal medium had slightly fewer but larger flowers and thicker stalks (section of the inflorescence between the base and oldest flower) than those in the 1 perlite:1 rockwool medium. Medium had no effect on stalk length. Two media (3 perlite: 3 Metro Mix 250: 1 charcoal and 1 perlite: 1 rockwool) resulted in root systems that were inferior to those in the others. Fertilizer level had no effect on bloom date or flower size. Regardless of medium, increasing the fertility from 0.25 to 1.0 g·liter-1 increased flower count, stalk diameter and length, and leaf production following flowering. During the second flowering season, media had limited effect on plant performance. Increased fertility promoted earlier inflorescence emergence and blooming. Higher fertilizer rates also caused a linear increase in the number of flowers and inflorescences per plant, and in stalk diameter, total leaf count, and leaf size.

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Abdul R. Kamali and Norman F. Childers

Abstract

Boron shortage resulted in limited growth, terminal dieback, pronounced bark lenticels and bark splitting; waxy, thick, brittle foliage; early defoliation; early leaf development after dormancy; fewer flower buds; longer blooming period; reduced pollen viability; poor fruit set and quality; fruit cracking and dry brown corky spots adjacent to the pit. Boron excess caused leaf distortion, shoot dieback, pit splitting, and leaf bud mortality after dormancy; increased break of lateral shoots; fewer flower buds; reduced pollen viability and fruit set; and faded flowers and anthers. Correction of B shortage or excess resulted in normal growth, flower bud formation, pollen viability, and fruit set and quality.

Based on growth response, symptom expression and fruiting, the B content of peach leaves can be correlated in the following manner: severe deficiency, less than 10 ppm; deficient, 11 to 17 ppm; low, 18 to 30 ppm; optimum, 31 to 59 ppm; high, 60 to 80 ppm; and excess, 81 to 155 ppm. There was a positive correlation between mean B content of leaves and that of the fruits. The symptoms of B injury suggested the following classification of the B status in the fruits; deficient, less than 10 ppm; normal, 11 to 29 ppm; and excess, 44 to 124 ppm. An application of fritted trace elements at the rate of 20–160 lb/A to sand in the crocks gave good vegetative growth the first season but was inadequate to support normal growth and fruiting the second season. An additional application of 40 or more lb/A near the end of the second growing season afforded normal growth, fruiting and fruit quality for the third season.

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Huan Hu, Nan Chai, Haoxiang Zhu, Rui Li, Renwei Huang, Xia Wang, Daofeng Liu, Mingyang Li, Xingrong Song, and Shunzhao Sui

Wintersweet (Chimonanthus praecox) is one of the most popular winter-blooming species. Effective vegetative propagation is necessary for commercial usage and protection of wintersweet. In the current study, the four factors, namely hormone type (A), hormone concentration (B), soaking duration (C), and medium (D), were assessed using an L16 (44) orthogonal test design. The hormone types include ABT (A1), α-naphthalene acetic acid (NAA) (A2), indole butyric acid (IBA) (A3), and indole-3-acetic acid (IAA) (A4); the hormone concentrations include 100 mg·L−1 (B1), 500 mg·L−1 (B2), 1000 mg·L−1 (B3), and 1500 mg·L−1 (B4); the soaking durations include 5 seconds (C1), 5 minutes (C2), 30 minutes (C3), and 3 hours (C4); and the mediums include perlite: peat in the ratios 1:0 (D1), 2:1 (D2), 1:1 (D3), and 1:2 (D4). The results showed that hormone and proper medium could significantly improve the cutting survival, rooting, and sprouting, whereas poor factor combinations, especially high hormone concentrations combined with long soaking durations may be threatened to the cuttings and rooting. In actual experiments, we successfully obtained an excellent rooting percentage (62.22%) of wintersweet from treatment No. 5 (A2B1C2D3), which is perlite and peat (1:1) as the medium and soaking the cuttings in 100 mg·L−1 NAA for 5 minutes as the hormone treatment. This combination can already meet the requirements for commercial production. A range analysis showed that the medium and hormone concentration were the most important factors affecting the cutting of wintersweet. An analysis of variance also showed that the medium and hormone concentration can significantly or extremely significantly affect most cutting indicators. Moreover, our results revealed that an orthogonal design method is an effective tool for establishing an improved technique for cutting propagation.

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Guglielmo Costa, Luca Corelli Grappadelli, and Fabrizio Bucchi

Experiments were carried out for 3 years on `Gala' and `Fuji' apple cultivars. The efficacy of the compounds applied during blooming (ATS, Armothin) and at 10 mm king fruit diameter (BA, CPPU, and NAA) was studied. Results showed a poor efficacy of the chemicals applied during bloom, while compounds applied at fruit set showed interesting results. Among the new chemicals, citokinins were the most effective, although their effects were related to the cultivar: BA performs better than CPPU on `Fuji' while vice versa on `Gala'. In addition, both chemicals induced a slightly higher °Brix content, and acidity level showed the tendency to increase L/D ratio of the fruits as compared to controls. Fruit thinning and the strategies to enhance fruit size are applied early in the season and the problem remains, to assess their effectiveness as early as possible in order to adapt the management techniques (e.g., further thinning, if applicable, or fine-tuning of nutrition and irrigation, etc.) to enable the fruit to reach their maximum potential development. A modelling approach proposed by Lakso et al. (1995) postulates that apples grow in weight according to an equation termed “expolinear” (Goudriaan and Monteith, 1990) because after an initial phase of exponential growth (cell division), the apple enters a phase of linear growth (cell expansion) lasting up to harvest. The effectiveness of a thinning agent can therefore be evaluated-and explained-in terms either of the number of cells of the cortex tissue, or of their volume, or both. In addition, assessing the slope of the linear phase as early as possible might provide a prediction tool to evaluate size at harvest. This paper presents data from apple thinning trials on several cultivars. The effectiveness of these applications has been evaluated via an analysis of the cell parameters (number, volume and intercellular spaces) of the fruit's parenchyma cortex tissue. Also, fruit growth data have been used to test the possibility to predict fruit size at harvest once the fruit reaches the phase of linear growth.

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James F. Hancock, Peter W. Callow, Sedat Serçe, and Phan Quynh Son

Variation in 14 horticultural traits of native octoploid Fragaria L. from North and South America was examined in a greenhouse. Significant levels of variation were found for all but a few of the traits at the species, subspecies, regional and genotypic level, with the highest amount of variation generally being partitioned among genotypes. Fragaria chiloensis (L.) Miller was superior to F. virginiana Miller for crown number, fruit weight, soluble solids and seed set, while Fragaria virginiana was superior for runner production, peduncle length, fruit number, fruit color and winter hardiness. Fragaria chiloensis ssp. pacifica Staudt had the highest soluble solids and among the earliest bloom dates, highest crown numbers and highest seed set. Fragaria chiloensis ssp. chiloensis f. chiloensis (L.) Duch. produced the largest fruit and among the earliest bloom dates and longest peduncles. Fragaria chiloensis ssp. chiloensis f. patagonica (L.) Duch. had among the highest crown numbers and the highest percentage seed set. Fragaria virginiana ssp. platypetala (Rydb.) Staudt produced the most crowns and its fruit ripened earliest. Fragaria virginiana ssp. glauca (Wats.) Staudt were the latest flowering, had the darkest fruit color and the most flowering cycles. Fragaria virginiana ssp. virginiana Duch. displayed the most winter dieback, the longest peduncles, and the highest flower and runner numbers. No significant differences were observed in any of the examined traits between F. chiloensis ssp. pacifica and F. chiloensis ssp. lucida, or F. virginiana ssp. grayana and F. virginiana ssp. virginiana. A number of individual genotypes were superior for more than one trait. CFRA 0024 possessed unusually high crown numbers, was extremely early blooming and displayed multiple fruiting cycles. CFRA 1121 had unusually long peduncles and much higher than average values for fruit weight, soluble solids, fruit color and seed set. CFRA 0094 was extremely early flowering and had much darker fruit color than most other F. chiloensis genotypes. CFRA 0368 flowered unusually early and had among the largest fruit. CFRA 0366 possessed unusually long peduncles and the largest fruit of any North American genotype. CFRA 0560 and CFRA 1369 had an unusual combination of multiple flowering cycles and high runner production. CFRA 1170 and 1171 were unusually late fruiting and had high numbers of large fruit on long peduncles. CFRA 1385 and JP 95-3-1 had extremely high flower numbers, long peduncles and large fruit.

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Lamprini Tassoula, Maria Papafotiou, Georgios Liakopoulos, and Georgios Kargas

The possibility of using Convolvulus cneorum L., a native Mediterranean xerophyte, with compact dome-like canopy and extended blooming period, on extensive green roofs in areas with semiarid Mediterranean climate was investigated in a 27-month experimental period, which included three summers (the dry season of the year). The aim was to preserve the local character and biodiversity, as well as to reduce water consumption and construction weight. Convolvulus cneorum rooted cuttings were planted in the beginning of July 2011 in experimental modules on a fully exposed flat roof at the Agricultural University of Athens, with a green roof infrastructure (substrate moisture retention and protection of the insulation, drainage element, and filter sheet). Two types of substrate with 10 cm depth were used, one with soil, i.e., grape marc compost:perlite:soil:pumice (3:3:2:2, v/v) and a lighter one without soil, i.e., grape marc compost:perlite:pumice (3:3:4, v/v). Two irrigation frequencies were applied during the dry periods, i.e., every 5 days (normal) and 7 days (sparse) in 2011 and 2012 and every 4 days (normal) and 6 days (sparse) in 2013. The chemical properties of the two substrates were similar, while their physical properties differ slightly as the substrate that contained soil was holding more water at saturation and it had lower saturated hydraulic conductivity and higher easily available water (EAW). The substrate type affected growth since plant height and diameter, shoot number, and aboveground dry weight were promoted by the soil substrate. Irrigation frequency did not affect plant growth. However, plants cultivated on soil substrate and irrigated normally had the highest growth, particularly compared with plants in soilless substrate under sparse irrigation. Flowering was abundant in April (spring) and in the first year flower number was promoted by the soil substrate. During the dry periods, sparse irrigation resulted in increased stomatal resistance one day before irrigation, indicating that water availability was marginal for the plants, while normal transpiration rate was restored the day after irrigation. According to photosystem II photochemical parameters measured one day before and the morning after an irrigation event, no evidence of damage to the photosynthetic apparatus was recorded in any of the treatments. In general, after 27 months of culture, plant size and roof coverage was appearing more or less similar in all the experimental treatments, therefore the combination of the lighter soilless substrate with sparse irrigation is highly suggested for C. cneorum cultivation on Mediterranean green roofs.

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Rafael Socias i Company and A.J. Felipe

possibility of becoming a commercial alternative to the two traditional almond cultivars in the Spanish market, ‘Marcona’ and ‘Desmayo Largueta’, to which they are comparable in their aspect and industrial quality but different from them in their late blooming