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).
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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
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’.
Nader R. Abdelsalam, Rehab M. Awad, Hayssam M. Ali, Mohamed Z.M. Salem, Kamel F. Abdel Latif and Mohamed S. Elshikh
Fig (Ficus carica L.) considers the original cultivated fruit trees and currently has become extinct. Such genetic resources should be identified, documented, and conserved. Morphology, pomology, and molecular markers are successful tools in assessing genetic diversity and classifying fig accessions. Twenty-one cultivated fig (F. carica L.) accessions were collected from Egypt and Libya. In Egypt, fig accessions are dispersed from Sinai in the east to El-Saloom in the west and from Alexandria in the north to Aswan in the south, whereas Libyan accessions were collected from Tubryq, Bengazi, and AlKufrah. Seventeen morphological, pomological, and fruit traits were used to characterize the fig accessions. Moreover, frozen young leaves were used to extract genomic DNA; 13 expressed sequence tag (EST) common fig primer pairs with 12 intersimple sequence repeat (ISSR)-anchored primers were used to detect the genetic diversity. Analysis of variance for fig accessions showed highly significant differences concerning morphological traits, i.e., the leaf length (centimeters) and width (centimeters) ranged from 5.4 and 6 cm to 23 and 23.5 cm, for Komesrey-El-Hammam, Abodey-Giza, and Black_Mission accessions, respectively. Also, fig accessions showed different shapes of leaf edge and fruits; they were categorized into four groups: straight, waved, zigzag, and serrated. The number of leaf lobes data ranged from one lobe for the ‘Green-yellow’, ‘Sultani Red Siwa’, and ‘Sultany Red Amria’ accessions to 10 lobes in the Aswany accession. The two-way hierarchical morphological cluster analysis distributed fig accessions into two main groups. The results detected high genetic diversity for the fig accessions that could be useful in the future breeding programs. Concerning molecular data, the EST markers showed highly polymorphism and informative (r = 0.61; 90.0%), with a total number of identified alleles of 78. We proved that a relatively greater number of alleles per locus characterizes the targeted loci among fig accessions, for which only one and two alleles per locus have been revealed, respectively, although ISSR showed a clear pattern and bands of the primers UBC807, UBC811, UBC812, UBC814, UBC815, UBC817, UBC818, and UBC823. In conclusion, a great range of variability was detected within the fig accessions. This diversification could enrich the genetic base of this genus, and more experiments are needed to reach its full potential.
Givago Coutinho, Rafael Pio, Filipe Bittencourt Machado de Souza, Daniela da Hora Farias, Adriano Teodoro Bruzi and Paulo Henrique Sales Guimarães
Among the fruit species cultivated in subtropical climates, quince has productive cultivars with high horticultural potential. The objectives of this study were to evaluate the genetic divergence among quince cultivars through multivariate procedures and to identify cultivars for cultivation in the tropics through selection indices. Twenty-seven productive quince cultivars were grown in a location with a high-altitude tropical climate. The number of fruit, estimated yield, flowering period, number of buds, number of shoots, number of brindles per shoot, shoot length, average fruit weight, fruit length, and fruit diameter were measured. A multivariate principal component analysis (PCA) associated with the unweighted pair group method with arithmetic means (UPGMA) based on Gower distance and Pearson correlation coefficients was used to evaluate genetic divergence. Superior cultivars were defined by the selection index based on the rank summation index and the Z-index. UPGMA grouping indicated there was genetic variability among cultivars and showed that groups that were more dissimilar [e.g., the cultivars Bereckzy and Champion (distance = 0.69)] had the potential to be used in future stages of quince selection. The estimated yield, shoot length, fruit weight and diameter, and flowering period contributed to the maximum variability among quince cultivars. The selection indices identified cvs. Bereckzy, Alaranjado, and Alongado (30, 68, and 73 rank summation index, respectively) as superior, simultaneously considering the evaluated traits with greater potential for cultivation in the tropics.
Karen L. Panter, Timmothy M. Gergeni, Casey P. Seals and Andrea R. Garfinkel
High tunnels are gaining popularity for their use in horticultural crop production. However, little is known about the effect of high tunnel orientation on plant growth and development. In this set of studies, we show tunnel orientation does not necessarily affect the production of cut sunflower (Helianthus annuus) and culinary herbs oregano (Origanum vulgare), marjoram (Origanum majorana), and garlic chive (Allium tuberosum). Two high tunnels, one with the long axis oriented north-south (NS) and the other east-west (EW), were used to test the effects of high tunnel orientation on several crops over a 5-year period: cut sunflower (2012 and 2016); marjoram, oregano, and garlic chive (2013 and 2014); and garlic chive (2015). The tunnels are 12 × 16 ft, smaller than those used in commercial production. The size would be appropriate for hobby and seasonal production of horticultural crops for local markets. Cut sunflower stems were similar lengths both years in both high tunnels. Sunflower times to harvest were different between cultivars but not between high tunnels. Oregano fresh weight yields were highest in the NS tunnel in 2013 but similar between tunnels in 2014. Marjoram fresh weights were highest in 2013 in the EW tunnel but highest in 2014 in the NS tunnel. Garlic chive fresh weights were similar between tunnels all 3 years. We show that differences are more a function of innate cultivar characteristics than which way small high tunnels are oriented.
Griffin M. Bates, Sarah K. McNulty, Nikita D. Amstutz, Victor K. Pool and Katrina Cornish
Rubber dandelion (Taraxacum kok-saghyz, Rodin) is being developed as a temperate-zone source of rubber, but best agronomic practices must be determined before it can become a viable supplement to imported rubber produced from para rubber tree (Hevea brasiliensis, hevea) plantations located mostly in Southeast Asia. In our study, the effect of planting density and harvest time on yield was determined by transplanting 1.5-month-old greenhouse-produced plants at planting densities of 1.24, 2.47, 4.94, and 9.88 million plants/ha, randomized across four planting boxes with two densities per box (i.e., two planting areas at each density). Half of each planting area was selected randomly and hand-harvested after 6 months, and the remaining plants were hand-harvested after 1 year. Rubber yields per plant were greater after 1 year than after 6 months, but yields per unit area were similar as a result of the loss of half the plants during the severe 2013–14 Ohio winter. A maximum rubber yield of 960 kg dry rubber/ha was obtained from the 9.88 million-plants/ha planting density after 1 year, but root size was significantly decreased compared with lower densities, and appeared too small for mechanical harvest. A planting density between 2.47 and 4.94 million plants/ha may produce the optimal combination of root size and total rubber yield. Greater rubber concentrations, faster-growing plants, short-season germplasm, and in-field weed control are required before yields obtained in outdoor planting boxes can be matched or exceeded on farms, especially in a direct-seeded rubber dandelion crop.
Shawn A. Mehlenbacher, David C. Smith and Rebecca L. McCluskey
Jinghua Guo, Yan Yan, Lingdi Dong, Yonggang Jiao, Haizheng Xiong, Linqi Shi, Yu Tian, Yubo Yang and Ainong Shi
Hydroponics has been an increasingly important field of vegetable production. However, a big issue with hydroponics is that certain crops can quickly accumulate high levels of nitrate-N (NO3 ± -N) from the hydroponic system. The objective of this research was to decrease NO3 accumulation and increase the nutritional value and yield of vegetable crops using lettuce and oilseed rape as a model under hydroponic production. In this study, two technologies were applied to leafy vegetable production: 1) using supplementary lighting (blue-violet diode) by manipulating illumination and 2) removing fertilization before harvest for a short term (3 or 5 days), thus providing a practical experiment for improving yield and edible qualities of hydroponic leaf vegetable production. Illumination was applied 4 hours a day (0500–0700 hr and 1700–1900 hr) during good weather, or 12 hours a day during bad weather with insufficient natural light (<2000 lux) during the autumn and winter seasons. Results showed that the lettuce cultivar Ou-Luo and the oilseed rape cultivar Ao-Guan Pakchoi had increased yield (50.0% and 88.3%, respectively), decreased NO3 content (26.3% and 30.8%, respectively), and increased total soluble solids (24.1% and 30.6%, respectively). The 5-day fertilizer-free treatment before harvest resulted in 19.2%, 6.4%, and 16.5% yield increases; and 26.0%, 24.3%, and 47.8% NO3 decreases in oilseed rape cultivar Ao-Guan Pakchoi and lettuce cultivars Da-Su-Sheng and Ou-Luo, respectively.
Xuelian Jiang, Yueling Zhao, Ling Tong, Rui Wang and Sheng Zhao
To investigate the quantitative response of tomato yield and fruit quality to deficit irrigation applied at different growth stages, greenhouse experiments were conducted in 2017 and 2018. Three irrigation treatments (full irrigation and two-thirds or one-third of full irrigation) were applied to greenhouse-grown tomato plants at flowering and fruit development (stage 2) and at fruit maturation stage (stage 3). Grey relational analysis (GRA), the technique for order preference by similarity to an ideal solution (TOPSIS), and principal components analysis (PCA) were used to calculate the comprehensive fruit quality indexes, and combinatorial evaluation method was determined. The results showed that deficit irrigation significantly reduced evapotranspiration (ET) and tomato yield and that relative yield had a negative linear correlation with relative seasonal water deficit (1−ETi/ETc). However, deficit irrigation improved fruit quality, especially at stage 2. Total soluble solids, the total soluble sugar concentration, the sugar-to-acid ratio, and vitamin C in the tomatoes all increased significantly in plants that were deficit irrigated compared with fully irrigated plants, while organic acids and lycopene decreased in both years. There were linear correlations between fruit quality parameters and 1−ETi/ETc. The comprehensive quality index derived from GRA and PCA is reliable, and the comprehensive quality indexes given by GRA, PCA, and a combination of GRA and PCA showed positive linear correlation with 1−ETi/ETc. The comprehensive quality ranking showed that in both years, F2/3M1 (two-thirds full irrigation at stage 2) gave a better result and CK (full irrigation) the worst. An appropriate water deficit at the flowering and fruit development stage, which results in a trade-off between acceptable yield and improved fruit quality, is recommended. Our results provide a sound basis for tomato production that has a desirable balance between high yield and high fruit quality.