Modern intensive agriculture has led to biodiversity loss by restricting the number of crops, resulting in a limited range of nutrients available to the community. Alternative specialty crops can contribute to crop diversification in agricultural production systems and enhance human health and well-being by providing a diverse array of food crops. Rapid demographic changes in the U.S. population has created higher demands for and sales potential of fruits and vegetables, and has brought new market opportunities for farmers in the United States to grow alternative specialty crops. The introduction of alternative specialty crops has many inherited advantages including economic benefits to farmers through multiple facets: diversifying crop with value-added crops, improving resilience to climate variability, maintaining yields with less resources, and boosting crop resistance to pests and diseases. However, there are challenges associated with the introduction and establishment of new crops, which include lack of information on candidates, cultural practices, and marketing as well as policy and institutional barriers. Farmers may face risk from poor economic returns and their businesses are likely to fail if proper management and marketing information are not available. This paper explores the opportunities and challenges associated with introduction of alternative specialty crops, and discuss how to mitigate potential problems associated with the introduction and establishment of alternative specialty crops.
Hye-Ji Kim and Xinxin Li
This study was undertaken to critically analyze the effects of reduced phosphorus (P) on shoot and root growth, partitioning, and phosphorus utilization efficiency (PUtE) in lantana (Lantana camara ‘New Gold’). Plants were grown in a 1:1 mixture of perlite and vermiculite with complete nutrient solutions containing a range of P concentrations considered to be deficient (1 mg·L−1), low (3 and 5 mg·L−1), adequate (10 mg·L−1), and high (20 and 30 mg·L−1). Higher P supply had most dramatic effect on increasing the number of leaves and leaf surface area, subsequently leading to a disproportionate increase in shoot biomass than root biomass. Increasing P from 1 to 30 mg·L−1 linearly (P < 0.0001) increased shoot dry weight (DW) during vegetative growth, and logarithmically (P < 0.0001) during reproductive growth. Regardless of plant growth stage, biomass of roots and flowers (inflorescences) logarithmically increased (P < 0.0001) with increasing P concentrations. Plants grown with lower P allocated more biomass to roots than shoots, resulting in a higher root-to-shoot ratio. Increasing P concentration to 20 mg·L−1 increased the accumulation of P in all plant parts, but predominantly in shoots, whereas further increasing the concentration increased the accumulation primarily in roots and flowers. Higher P accumulation in plant tissues did not strongly contribute to the biomass production. Phosphorus utilization efficiency was higher with lower P supply in all plant tissues. P-deficient roots had the highest PUtE and specific root length (SRL), and retained higher proportion of P compared with nondeficient roots. Our results indicate that P concentration at 20 mg·L−1 is sufficient to maintain optimal vegetative growth while reproductive growth does not require P concentrations over 10 mg·L−1 as it stimulates greater level of P accumulation in plant parts with little or no effect on growth and flowering, and biomass accumulation in lantana.
Hye-Ji Kim and William B. Miller
The effect of GA4+7 plus benzyladenine (BA) on postproduction quality was investigated in `Seadov' tulips (Tulipa gesneriana). Potted tulips at half-colored bud stage or full-bloom stage were sprayed with a range of GA4+7 plus BA, and placed in a simulated consumer environment (SCE) in order to determine effectiveness of the compound at each stage. Regardless of plant stage, treatment with GA4+7 plus BA effectively improved individual flower longevity and whole plant longevity in the range of concentrations tested. GA4+7 plus BA had a strong effect on enhancing flower longevity when sprayed to mature (fully colored) buds, and a lesser effect on immature (green) buds, and whole plant longevity increased with higher doses of GA4+7 plus BA. When applied to open flowers, however, concentrations over 50 mg·L–1 reduced individual flower and whole plant longevities relative to lower concentrations resulting from unwanted full-opening of older flowers and exaggerated gynoecium growth. Concentrations as low as 10 mg·L–1 significantly increased longevity of tulip flowers of all age classes. The effects of enhancing postproduction quality of `Seadov' pot tulips were primarily derived from the BA component of the compound.
Hye-Ji Kim, Richard Craig, and Kathleen M. Brown
Ethylene induces significant petal abscission in regal pelargonium (Pelargonium ×domesticum L.H. Bailey). Three genotypes, `Elegance Silver' and its progeny, 00-43-1 and 00-43-2, were developed with exceptional production and postproduction characteristics. These genotypes had significantly enhanced individual floret longevity and whole plant longevity, and displayed more than twice as many florets as commercial cultivars. Dose response analysis demonstrated that `Elegance Silver' has reduced ethylene responsiveness throughout floret development, shown by lower petal abscission than other cultivars over a range of ethylene concentrations. Floret longevity was strongly correlated with ethylene responsiveness as indicated by S50 (ethylene concentration for 50% petal abscission), but not with ethylene production. These results suggest that reduced ethylene responsiveness is an important determinant of enhanced postproduction performance in the superior genotypes of regal pelargonium.
Jiaqi Hu, Hye-Ji Kim, Houbin Chen, and Biyan Zhou
Short vegetative phase (SVP), a MADS-domain transcription factor, was shown to act as a repressor of flowering in arabidopsis (Arabidopsis thaliana). Although the role of SVPs in flowering is well characterized in the model plant arabidopsis, little is known in evergreen woody litchi (Litchi chinensis). In this study, three litchi SVP homologs (LcSVP1, LcSVP2, and LcSVP3) were cloned, and the bioinformatic analysis of the LcSVPs was carried out to identify their molecular characteristics. Their expression patterns in the apical meristem (AM) during the transition from vegetative to reproductive phase were studied under natural flowering inductive conditions. Also, brassinosteroid (BR) treatment under low temperature conditions was performed to elucidate the role of LcSVPs in the BR-regulated flowering. The results showed that LcSVPs belonged to the MADS superfamily. LcSVP relative expression levels in AMs of the early- and late-flowering cultivars showed decreasing trends with the transition from vegetative to reproductive growth. Under low temperature condition, relative expression levels of LcSVP1, LcSVP2, and LcSVP3 in AMs or panicle primordia showed decreasing trends, whereas those in the AMs of the BR-treated trees remained at relatively high levels. Relative expression analysis of the litchi homolog, flowering locus t 1 (LcFT1), showed that the BR-treated leaves had lower relative expression level than nontreated control leaves. The findings suggest that LcSVPs act as repressors involved in flowering in natural conditions and the BR-regulated flowering.
Hai-Fang Yang, Hye-Ji Kim, Hou-Bin Chen, Jillur Rahman, Xing-Yu Lu, and Bi-Yan Zhou
Litchi trees flower at the apex of terminal shoots. Flowering is affected by the maturity of terminal shoots before growth cessation occurs during the winter. In this study, we focused on changes of flowering in three important cultivars, Guiwei, Feizixiao, and Huaizhi, from Dec. 2012 to Mar. 2013 under natural winter conditions. Flowering rate, carbohydrate accumulation, and expression of the flowering-related genes were determined at three different developmental stages of terminal shoots with dark green, yellowish green and yellowish red leaves, respectively. The results showed that the total soluble sugar and starch contents in the dark green leaves were the highest, whereas those in the yellowish red leaves were the lowest. Trees with dark green terminal shoots had the highest flowering rates, whereas those with yellowish green or yellowish red shoots had relatively lower flowering rates. SPAD was highest in dark green leaves and lowest in yellowish red leaves at the start of the trial. The SPAD value of yellowish red leaves slightly increased but did not reach the levels of the dark green leaves, whereas levels of the other leaf stages remained fairly constant. Expression level of the litchi homolog FLOWERING LOCUS C (LcFLC), the floral inhibitor in yellowish red leaves, increased from 16 Jan., whereas that in dark green leaves declined to a level lower than the yellowish red leaves on 4 Feb. Expression level of the litchi homolog CONSTANTS (LcCO), the floral promoter in dark green leaves, was higher than that of yellowish red leaves before 26 Jan. Expression level of the litchi homolog FLOWERING LOCUS T 2 (LcFT2), encoding florigen, was higher in dark green leaves than in the other two leaf types. Our results suggest that terminal shoots should be matured and leaves should turn green for successful flowering. Mature leaves had higher expression levels of the floral promoter and florigen. In litchi production, leaves of the terminal shoots (potential flowering branches) should be dark green during floral induction and differentiation stages, and winter flushes should be removed or killed.
Celina Gómez, Christopher J. Currey, Ryan W. Dickson, Hye-Ji Kim, Ricardo Hernández, Nadia C. Sabeh, Rosa E. Raudales, Robin G. Brumfield, Angela Laury-Shaw, Adam K. Wilke, Roberto G. Lopez, and Stephanie E. Burnett
The recent increased market demand for locally grown produce is generating interest in the application of techniques developed for controlled environment agriculture (CEA) to urban agriculture (UA). Controlled environments have great potential to revolutionize urban food systems, as they offer unique opportunities for year-round production, optimizing resource-use efficiency, and for helping to overcome significant challenges associated with the high costs of production in urban settings. For urban growers to benefit from CEA, results from studies evaluating the application of controlled environments for commercial food production should be considered. This review includes a discussion of current and potential applications of CEA for UA, references discussing appropriate methods for selecting and controlling the physical plant production environment, resource management strategies, considerations to improve economic viability, opportunities to address food safety concerns, and the potential social benefits from applying CEA techniques to UA. Author’s viewpoints about the future of CEA for urban food production are presented at the end of this review.