Late frost is the number one issue challenging fruit production in northern New Mexico. We had apricot (Prunus armeniaca) trees in an open field planting at Alcalde, NM, and not a single fruit was harvested from 2001 through 2014. Apricot trees in surrounding communities produce sporadic crops. In 2012, we planted apricots in two 16 × 40-ft high tunnels (9.5-ft high point). Trees were trained to a spindle system in one high tunnel and an upright fruiting offshoot (UFO) system in the other, and there were identical plantings in the open field for each high tunnel. Supplemental heating was provided starting at blooming time. There were five cultivars planted in each high tunnel at 4 × 8-ft spacing in a randomized complete block design with two replications (rows) and two trees per cultivar in each plot. In 2015, relatively high yields were obtained from all cultivars. The average yields for the spindle system were (lb/tree): ‘Puget Gold’ (29.0), ‘Harcot’ (24.1), ‘Golden Amber’ (19.6), ‘Chinese Apricot’ (18.6), and ‘Katy’ (16.7). Yields for the UFO system were (lb/tree): ‘Golden Amber’ (18.6), ‘Katy’ (14.9), ‘Puget Gold’ (11.3), ‘Chinese Apricot’ (10.2), and ‘Harcot’ (8.6). On average across all cultivars, the UFO system produced 60% of the yield of the spindle system in 2015. A heating device is necessary for high tunnel apricot fruit production in northern New Mexico because trees normally bloom in early to late March, depending on the year, while frosts can continue until mid-May. In years like 2017 and 2018 with temperatures below 10 °F in late February/early March, some of the expanded flower buds were killed before bloom. On those cold nights, one 100-lb tank of propane may or may not be enough for 1 night’s frost protection. Economically, it would not be feasible in those years. Only in years with a cool spring, late-blooming trees, and mild temperatures in April and May can high tunnel apricot production generate positive revenue with high, direct-market prices. High tunnel apricot production with heating devices is still risky and cannot guarantee a reliable crop in northern New Mexico or similar areas.
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Shengrui Yao, Steve Guldan and Robert Heyduck
Carol A. Miles, Thomas S. Collins, Yao Mu and Travis Robert Alexander
Two studies were performed in Mount Vernon, WA, to identify bulb fennel (Foeniculum ×vulgare) cultivars and seeding practices best suited for the region. The first study evaluated 13 cultivars (Bronze, Finale, Florence, Genesi, Idillio, Orazio, Orion, Perfection, Preludio, Solaris, Tauro, Tenace, and Zefa Fino) over the course of 2 years; during the second year, the additional main factor of the seeding date was included. The second study evaluated three bulb fennel cultivars (Finale, Tauro, and Zefa Fino), four seeding dates (17 May, 31 May, 14 June, and 28 June 2018), and two planting methods (direct and transplant). Results of the two studies demonstrated that ‘Finale’, ‘Orazio’, ‘Preludio’, ‘Solaris’, and ‘Tenace’ had the greatest bulb production rate and yield and good bulb quality that met marketability standards. ‘Genesi’, ‘Orion’, and ‘Perfection’ had good bulb production during only 1 of the 2 years, whereas ‘Bronze’, ‘Florence’, ‘Idillio’, and ‘Zefa Fino’ had very low bulb productivity both years due to bolting. ‘Perfection’ and ‘Tauro’ exhibited internal cracking both years (incidence rates of 9.5% and 12.8%, respectively). The first harvest was 94 to 112 days after seeding during the first study. Direct seeded bulb fennel required 32 fewer days to harvest than transplanted bulb fennel during the second study. The average bulb circumference was 28.1 cm, with little variation between studies. Bulb tenderness for both studies was 617 g-force, on average, and the soluble solids concentration of bulbs in both studies was 4.9%. Ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry based on 38 tentatively identified compounds demonstrated no difference in the phenolic content of bulb fennel due to the cultivar. In conclusion, bulb fennel cultivars well-suited for production in northwest Washington were identified and direct seeding was demonstrated to be a better planting method than transplanting.
Suzanne P. Stone, George E. Boyhan and W. Carroll Johnson III
The southeastern United States produces 50% of U.S. conventional watermelon (Citrullus lanatus) but only 7% of U.S. organic watermelon. Weeds are a major threat to watermelon yield in the southeastern United States, and organic weed control is estimated to cost 20-times more than conventional herbicide programs. The objectives of this study were to determine the optimal weed control regime to reduce hand-weeding costs while maintaining yield and to compare the weed suppression of two watermelon types with differing growth habits in an organic system. In 2014 and 2015, watermelon plots were randomly assigned to the following treatments in a factorial arrangement: vine or compact growth habit; 1.0- or 0.5-m in-row spacing; and weekly weed control (kept weed-free by hoeing and hand-pulling weeds) for 0, 4, or 8 weeks after transplanting (WAT). At the time of the watermelon harvest, not weeding resulted in average total weed densities of 86.6 and 87.0 weeds/m2, and weeding for 4 WAT resulted in average total weed densities of 26.4 and 7.0 weeds/m2 in 2014 and 2015, respectively. Nonetheless, weeding for 4 WAT resulted in watermelon yields and fruit counts comparable to those of weeding for 8 WAT during both years. This partial-season weeding regime resulted in 67% and 63% weeding cost reductions for vine and compact plants, respectively, in 2014, and a 43% reduction for both growth habit types in 2015. In 2015, a separate experiment that evaluated weeding regimes that lasted 0, 1, 2, 3, 4, and 8 WAT found that yields resulting from weeding for 3 WAT were greater than those resulting from weeding for 2 WAT. However, the yields did not differ when weeding was performed for 4 WAT and 8 WAT.
Ed Etxeberria, Pedro Gonzalez, Ariel Singerman and Timothy Ebert
Monitoring the health of Huanglongbing-affected citrus trees by following changes in leaf Candidatus Liberibacter asiaticus (CLas) titer has an inherent element of imprecision because CLas titer varies considerably within the tree canopy and with calendar seasons. In addition, the destructive sampling method used to determine CLas titer entails a different set of leaves per sampling period adding to the inconsistency and inexactitude of the results. To overcome these ambiguities and to reduce the numerical variability between samples, we developed an experimental method that analyzes portions of the same treated leaves for up to four sampling periods. By assaying subsamples of adjacent locations of the same leaf, random variability was significantly reduced, and comparative analysis can be carried out with greater precision.
Elias A. Moura, Pollyana C. Chagas, Edvan A. Chagas, Railin R. Oliveira, Raphael H. Siqueira, Daniel L.L. Taveira, Wellington F. Araújo, Maria R. Araújo and Maria L. Grigio
Sugar apple fruit are widely appreciated because of their flavor and functional qualities. However, the final value of the fruit varies according to its physical, physicochemical, and organoleptic qualities. The production and attributes that make up the quality of fruit can be influenced by climatic seasonality in both seasons (dry and wet). Therefore, this work aimed to evaluate whether the production and quality of fruit production of different size classes of A. squamosa L. in two seasons are affected by climatic seasonality. The experiment consisted of a randomized block design, with 4 blocks and 10 plants per block. The variables evaluated were number of fruit per hectare, production, and yield. The postharvest evaluation of the fruit consisted of a completely randomized experimental design, in a 3 × 2 factorial scheme, which referred to the three sizes and two seasons, and evaluated fruit length and diameter; firmness; fruit, bark, and seed weight; number of seeds; soluble solids; hydrogen ionic potential (pH); titratable acidity (TA); and ratio. The 2014 season had larger fruit in relation to those of the 2015 season; conversely, it showed a lower number of fruit per plant, production, and yield, besides inferior organoleptic quality. Fruit of size class 2 stood out in the 2014 season because of their physical characteristics. However, they had inferior organoleptic quality when compared with fruit of the same size collected during the 2015 season. Fruit of size class 3 (≥8.1 cm) had greater firmness, providing longer durability and shelf life.
Jie Zhang, Hong-yan Liu, Xin-yu Qi, Ya-nan Li and Ling Wang
Mehmet Sütyemez, Şakir B. Bükücü and Akide Özcan
M.E. El-Mahrouk, A.R. El-Shereif, Y.H. Dewir, Y.M. Hafez, Kh. A. Abdelaal, S. El-Hendawy, H. Migdadi and R.S. Al-Obeed
Hyperhydricity is a physiological disorder impacting plant growth and multiplication and acclimatization of regenerated plantlets. We report the use of calcium nitrate for reversion and acclimatization of banana ‘Grand Naine’ hyperhydric shoots cultured on Murashige and Skoog medium containing agar or gellan. Although 100% rooting of hyperhydric shoots occurred at all concentrations of calcium nitrate, only 50% rooting was recorded in the absence of calcium nitrate. Electrolyte leakage decreased significantly in the reverted banana tissues compared with the hyperhydric tissues. Histochemical staining for reactive oxygen species indicated that reverted banana tissues possess lower levels of both hydrogen peroxide (H2O2) and superoxide (O2 -) than do hyperhydric tissues. Rooting, growth, and survival of the reverted banana plantlets were significantly influenced by calcium nitrate concentrations as well as the type of gelling agent. Reverted banana plantlets in medium containing calcium nitrate (0.5–1 g·L−1) were acclimatized with 100% survival in a growing substrate of peatmoss and vermiculite (1:1).
Kim D. Bowman, Greg McCollum, Anne Plotto and Jinhe Bai
Yanmei Zhang, Xuelin Shen, Xiaoqin Sun, Jia Liu, Yifeng Xia, Xin Zou and Yueyu Hang
Water chestnut (Trapa natans L.) is a group of annual, floating-leaved aquatic plants that serves as food and medical resources in many countries. However, the molecular method for distinguishing different T. natans L. resources is lacking. In this study, we detected genetic diversity of several chloroplast and nuclear genic or intergenic sequences in four varieties of T. natans and one wild type of Trapa incisa Siebold & Zuccarini to evaluate their potential as molecular markers. Our data revealed that the three chloroplast fragments (rbcL, matK, and pbsA-trnH) show no sequence difference among all tested samples. Only one nucleotide substitution is detected for the nuclear ribosomal internal transcribed spacer (ITS) in the T. natans variety Shuihongling. Four nucleotide substitutions are detected for the nuclear carotenoid isomerase (CRTISO) gene in the variety Hongxiuxie. In contrast, a total of 29 polymorphic sites are detected for a Toll and interleukin-1 receptor-nucleotide binding site–leucine rich repeat (TNL) gene in the five samples, among which six are nucleotide substitutions and the rest are insertions/deletions. The five samples could be fully distinguished from each other based on the TNL gene. To specifically authenticate ‘Heshangling’, 33 randomly amplified polymorphic DNA (RAPD) markers were adopted to amplify genomic sequences from the five samples. A pair of sequence characterized amplified region (SCAR) primers were designed based on the results of RAPD markers, which could specifically amplify one target band from all eight individuals of ‘Heshangling’, but none from any individuals of other T. natans varieties or one T. incisa. Taken together, a TNL sequence was provided in this study to distinguish four T. natans varieties and one T. incisa. Furthermore, a RAPD-SCAR marker was developed for efficient authentication of ‘Heshangling’.