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Open access

Haijing Fu, Wangbin Ye, Ruiyang Zhao, Yingxuan Dai, and Ling Wang

The genus Iris includes ≈300 species widely distributed in the temperate regions of the Northern Hemisphere, and many of them are attractive ornamentals that are largely used as groundcover plants for gardening and landscaping (Boltenkov et al., 2020). However, the leaves of most Iris species are high and prone to lodging easily, thus affecting their ornamental appearance. Therefore, dwarf Iris plants are desirable and popular. Because dwarf cultivars of some Iris species are relatively rare (Huang et al., 2003), there is a strong demand for dwarfing breeding of

Open access

Heidi Hargarten, James Mattheis, and Loren Honaas

Production of high-quality tree fruit requires management of tree health and vigor during orchard establishment, especially with regard to soil-borne pathogens. Available strategies for the mitigation of soil-borne diseases include chemical fumigants, Brassicaceous seed meal (SM) soil treatments, and the use of disease-tolerant rootstock genotypes. It has been documented that superior disease suppression can be achieved using specific combinations of rootstock genotype and soil treatment that, in part, alter the soil microbiome. However, regardless of soil treatment strategy or rootstock genetics, sublethal levels of phytotoxic compounds are known to have negative effects on the reproductive output of plants. Yet the effects of SM amendments and the resultant restructuring of the soil microbiome on fruit quality are not well studied. Thus, our objective was to explore the effects of pathogen suppression strategies on at-harvest and postharvest fruit quality of ‘Gala’ apples (Malus domestica) by observing effects of both rootstock genetics [‘Malling 26’ (‘M.26’) vs. ‘Geneva 41’ (‘G.41’)] and soil treatment strategy (fumigation vs. SM). We observed that rootstock genotype generally appeared to have a stronger effect than soil treatment strategy on at-harvest fruit quality and postharvest outcomes. Further, although we did observe some fruit quality differences in each year of the study, there was no discernible pattern from year to year. We therefore conclude that, in our study, soil treatment does not have a consistent, significant influence on ‘Gala’ apple fruit quality, and importantly, efficacious ARD control using SM is without an apparent downside regarding fruit quality.

Open access

Sijie Wang, Haoyi Wu, Haiying Li, Yaxin Zhao, Juan Zhou, Chen Lian, Jingran Lian, and Yan Ao

Bunge, a member of the Sapindaceae family, is a deciduous shrub or tree that is primarily distributed in north China. Xanthoceras sorbifolium is considered to be an ideal oil-rich seed tree species that has significant ecological, economic, and medicinal value (Ao, 2012; Liu et al., 2017). It can grow well in cold, barren environments, and even in saline-alkali land. It is also a valuable ornamental landscaping plant because of its beautiful form and luxuriant, colorful flowers. It has a long blooming period and flowers later than apricot (Armeniaca vulgaris Lam.) and peach

Open access

Lenny Wells and Andrew Sawyer

Site selection is key to successful establishment of fruit and nut trees. The upland soils on which pecan [Carya illinoinensis (Wangenh.) K. Koch] trees are commonly planted in the southeastern United States consist of sites that have recently been in row crop cultivation or pine or hardwood timber. Anecdotal observation suggests that orchards planted to land converted from cultivated row crop fields tends to result in better tree growth and survival than those on land recently converted from timber plantations or wooded areas. The objective of this experiment was to compare growth of first- through third-leaf pecan trees planted on sites with varying land-use history [row crop cultivation or pine (Pinus spp.) tree production up to the year before planting] and to determine the effects of supplemental addition of phosphorus (P), potassium (K), and zinc (Zn) at planting on the two sites. These results suggest that the soil conditions of sites recently in pine timber production limit the growth and development of pecan trees planted to those sites. These limitations result from soil acidity and an exhaustion of soil nutrients and loss of organic matter on pine sites, making the uptake of nitrogen (N), P, K, and calcium (Ca) challenging during the establishment phase unless soils are improved before planting.

Open access

Chunlan Li, Panyun Xu, Aote Zhou, Jinlong Song, Yuxia Wu, and Tianming He

This study investigated the ploidy of ‘Mianli’ with flow cytometry and the traditional chromosome squash technique. Its pollination biology and the occurrence and formation of embryo sacs before and after flowering were observed in paraffin sections to characterize its embryo sacs. The intersimple sequence repeat (ISSR) marker technique was used to test the uniformity of progeny of ‘Mianli’ treatments. The chromosome number of ‘Mianli’ is 2n = 2x = 34. The ploidy results were consistent with those identified by flow cytometry. ‘Mianli’ is male-sterile, and the anatropous ovule has double integuments. ‘Mianli’ can bear fruit normally and produce fertile seeds under the treatments of emasculation with bagging or no emasculation with bagging, but the seed yield is very low and significantly lower than that under artificial pollination or natural pollination. The developmental process of embryo sacs under natural pollination showed that most megasporocytes develop into mature sexual embryo sacs through meiosis and a few megasporocytes degenerate. Some sexual embryo sacs continue to develop into embryos after fertilization, and some sexual embryo sacs are aborted. In addition, new aposporous initial cells are generated irregularly at each stage from the emergence of megasporocyte to the end of sexual reproduction or abortion. The observation of the development of embryo sacs under emasculation with bagging showed that after pollination is blocked, mature sexual embryo sacs degenerate, and aposporous mononucleate embryo sacs appear around the degenerated sexual embryo sacs or in the peripheral tissues. Then, the process of proembryonic masses developing into spherical embryo was observed. A genetic uniformity analysis of progeny of ‘Mianli’ using ISSR was performed. The results showed that the progeny population under emasculation with bagging has high consistency at the molecular level, with some plants having full consistency with the female parent’s banding pattern, demonstrating consistency with the maternal genetic characteristics. The progeny under artificial pollination or natural pollination do not have the same banding pattern as the female parent. Because there is no pseudogamy, all of the progeny are true hybrids. In summary, it seems that ‘Mianli’ only has sexual reproduction in the presence of pollen, and only a few ovules are stimulated to undergo apomixis after pollination is blocked.

Open access

Bernadine C. Strik and Amanda J. Davis

A 6-year trial was established in Oct. 2015 in western Oregon to evaluate the effects of pruning and trellising on yield, hand- and machine-harvest efficiency, fruit quality, and costs of pruning and harvest of ‘Legacy’ highbush blueberry (complex hybrid based largely on Vaccinium corymbosum L. and Vaccinium darrowii Camp.). Pruning treatments began in Winter 2017–18 (before year 3) and continued each year through 2020–21 (year 6). Treatments included 1) recommended pruning for ‘Legacy’, removing less wood and leaving more short, thin laterals and a denser bush than is typical for most northern highbush cultivars (“control” with standard T-trellis), 2) control pruning and training to a V-trellis (“V”), and 3) standard northern highbush style pruning (“HB” with standard T-trellis). Fruit were harvested solely by hand in 2017 and 2018, and by hand for early harvests followed by machine for later harvests from 2019 to 2021. In most years, more wood was removed from HB- than control-pruned plants. On average, HB-pruned plants had a lower yield (6.7 kg/plant) than control-pruned plants, particularly those trained to a V-trellis (7.5 kg/plant). There was little effect of pruning treatment on fruiting season and hand- (7% drop) or machine-harvest efficiency (23% drop). Pruning method had no effect on berry weight, diameter, total soluble solids, or firmness over the study period or percent internal bruising in 2019. All of the ‘Legacy’ pruning methods studied required more time (358 to 561 h·ha−1) than the industry standard, ‘Duke’ (247 h·ha−1). Control and HB pruning did not differ in time to prune per unit area; however, in 2 of the 4 years, adding a V-trellis increased pruning time. On average, control and HB pruning had a similar cost per harvested fruit ($0.20 to $0.21/kg), whereas control pruning with a V-trellis ($0.23/kg) cost more than HB pruning. All treatments required the same amount of time to harvest (12.7 and 0.5 min·kg−1 for hand and machine picking, respectively). Total cost to prune and harvest ranged from $1.63/kg in 2019 to $3.43/kg in 2021 but was most heavily influenced by harvest costs rather than pruning. The one-time installation cost of $637/ha for the V-trellis was not compensated for by increased yield or efficiency of pruning or harvest compared with the control method with a standard T-trellis. Pruning according to recommended methods for ‘Legacy’ (control) increased yield without having a negative effect on fruit quality and had similar or lower costs to prune per kg of fruit harvested as typical northern highbush pruning.

Open access

Xinwang Wang, Keith Kubenka, Warren Chatwin, Tommy Thompson, and L.J. Grauke

‘Pueblo’ is a new pecan (Carya illinoinensis) cultivar released and patented by the U.S. Department of Agriculture, Agricultural Research Service (USDA ARS). This cultivar is the first to be released with a compact tree size, great precocity, early nut maturation, high yield potential, and scab resistance. ‘Pueblo’ should perform well in the West, central Texas, and as far north as southeastern Kansas. ‘Pueblo’ is the first of three patented pecan cultivars in the USDA ARS Pecan Breeding Program (U.S. Patent Application Serial No. 17/506,091). Parties interested in licensing ‘Pueblo’ should contact license@usda.gov with any questions. Graft

Open access

Lijuan Fan, Wangbin Ye, Haijing Fu, Ruiyang Zhao, Gongfa Shi, Rutong Lv, Lei Yan, Zhuowen Li, and Ling Wang

Irises have high ornamental values because of their decorative flowers and the elegance of their elongated leaves (Roguz et al., 2020; Xu et al., 2017). For example, Iris sanguinea has a blue flower color that offers great potential for landscaping. It also has strong disease resistance, and is cold and moisture tolerant (Bi et al., 2011; Shang and Wang, 2014). Thus, it could be widely used for gardening and landscaping in northeastern China. These factors have encouraged the development and release of new iris cultivars. Recently, new cultivars with various

Open access

Jiaqi Xia and Neil Mattson

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible succulent plant with savory flavor. It has epidermal bladder cells (EBCs) that store water and sodium chloride (NaCl) located on the epidermis of the leaves and stems. Ice plant is an obligatory halophyte that requires NaCl for optimum growth. The objective of this study was to determine the impact of NaCl on growth of ice plant for hydroponic production as an edible leafy green and to quantify the ability of ice plant to take up NaCl from the environment. Four-week-old seedlings of ice plant were transplanted into hydroponic systems, established for 1 week, and given five NaCl treatments [0 M (control), 0.05 M, 0.10 M, 0.20 M, 0.40 M NaCl]. Sequential destructive harvests to determine plant growth occurred at day 7, 14, and 21 after NaCl treatment. The 0.05 M NaCl had the greatest stimulating effect on biomass, increasing total fresh weight (FW) by 173% and shoot FW by 193% compared with the control plants. The 0.10 M NaCl also had stimulating effect as compared with 0 M, but plants were not as large as those receiving 0.05 M NaCl. The 0.20 M NaCl had little effect on plant growth compared with the control. The 0.40 M NaCl had a strong stunting effect on plant growth. All plants treated with NaCl had less root weight than the control, and higher NaCl concentration resulted in greater reduction in root weight. However, for the 0.05 and 0.10 M treatment, the gain in shoot weight exceeded the loss in root weight. Plants gained or lost water in a faster rate than dry mass, which resulted in larger differences among treatments in FW than in dry weight (DW). Plants treated with higher NaCl concentrations developed fewer, smaller, and thicker leaves but contained more EBCs per unit leaf surface area. There was high Na and Cl accumulation in leaf tissues of all salt-treated plants (e.g., 180,507 mg·kg−1 Na and 125,084 mg·kg−1 Cl in the 0.05 M treatment vs. 13,558 mg·kg−1 Na and 12,991 mg·kg−1 Cl in the 0 M treatment). This indicated potential for bioremediation of saline soil or hydroponic water. Concentrations of macronutrients such as nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), and sulfur (S) were reduced when plants received increasing NaCl treatments. In general, this study showed that growth of ice plant benefited from 0.05 and 0.10 M NaCl additions to the hydroponic nutrient solution. Ice plant deserves further work on its ability to reduce Na and Cl from accumulating in recirculating hydroponic nutrient solution.

Open access

Kaitlin A. Hopkins, Michael A. Arnold, Charles R. Hall, H. Brent Pemberton, and Marco A. Palma

Variation in floral characteristics and growth habits within the native range of the North American wildflower Ratibida columnifera (Nutt.) Wooton & Standl. suggests potential for breeding and selection efforts to develop improved cultivars for commercial and residential landscapes. Experiments in seed propagation were performed to enable perpetuation of unique germplasms. Overnight hydration, storage condition variations, stratification and scarification, and seed maturation effects were assessed to determine impacts on viability and percent germination. Overnight hydration had no impact on percent germination. Germplasm had a significant effect on germination for all remaining experiments. Seed maintained viability at the same rate through 18 months, when slight reductions were noted. Cold storage at 3 °C had no effect on viability or percent germination of dry seed compared with storage at 23 °C. All three germplasms exhibited increased percent germination with some stratification period, and declined significantly in percent germination with all acid scarification treatments. Experiments indicated that most germplasms benefit from between 30 to 60 days of cold, moist stratification. There was a significant interaction effect among germplasms, location on the inflorescences, and maturity stages for R. columnifera. Data suggest that seed should be harvested as close as possible to when natural dispersal would occur for optimum germination. The degree of improvement in viability and percent germination associated with harvesting at various developmental stages, seed pretreatments, and storage conditions suggests that to achieve germination success, pretreatments should be used for propagation of seed from mature inflorescences and that variation can be expected within different genotypes of this species.