This study investigated the effects of different temperature treatments (18, 24, and 30 °C) on apex development in tropical cauliflower cultivars of varying maturity types. Two commercial cultivars, H-37 (early maturity) and H-80 (mid–late maturity), were used as the testing materials. ‘H-37’ reached the curd-initiation phase earlier than ‘H-80’ and showed superior growth during the curd’s initial development phase under all temperature treatments. Analysis of variance revealed significant effects regarding main temperature and cultivar as well as their interaction. ‘H-37’ at a temperature of 18 °C demonstrated the optimal transformation of apex development from the vegetative to reproductive stage. A temperature of 24 °C promoted the apex development of ‘H-37’ at the curd initial development phase. Gene expression analysis results indicated that the BoFLC2 expression of ‘H-37’ was significantly down-regulated than that of ‘H-80’ after curd initiation and advanced growth. A temperature 30 °C accelerated the ending of juvenile stage and forward to curd initiation in ‘H-80’ and declined with temperature decreased. Moreover, expression of the BoFLC2 transcript level of both tropical cauliflower cultivars nearly disappeared at the high temperature of 30 °C following curd initiation, suggesting that heat stress hinders curd formation. The results of this study also indicate that the number of leaves required to induce curd initiation is less than nine in tropical cauliflower at temperatures of 18 to 30 °C. In conclusion, under nonvernalized high temperatures, different cultivars of tropical cauliflower can initiate curd development but with a different pattern from those cultivars grown in temperate zones. This information may provide novel insights for cauliflower farmers or breeders in tropical regions.
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Chen-Yu Lin, Kan-Shu Chen, Hsuan-Ping Chen, Hsiang-I Lee and Ching-Hsiang Hsieh
Alyssa J. Brown, Phil S. Allen, Greg V. Jolley and J. Ryan Stewart
For the past several years, many college horticulture programs have experienced a decline in undergraduate enrollment, resulting in the elimination of some degrees. In this study, we compared postsecondary U.S. horticulture program availability from a survey completed in 1997 with offerings existing in 2012 and 2017. In 1997, 446 U.S. postsecondary institutions offered degrees and/or certificates in horticulture. In 2012, this number had decreased by 43% to 253 institutions, which included 98 with 4-year degrees, 215 with 2-year degrees, and 138 with certificate programs. In 2017, the total number of institutions offering horticulture-related degrees and/or certificates decreased to 209, representing a 53% decrease over the 20 years from 1997 to 2017 and a 17% decrease during the 5-year period between 2012 and 2017. In 2017, 85 institutions offered 4-year degrees, 133 offered 2-year degrees, and 98 offered certificate programs, which over this 5-year period represents decreases of 13%, 38%, and 29%, respectively. “Horticulture” was the most common program title in both 2012 and 2017, and the percentage of programs with this name increased during the 5-year period for all program types. In 2017, 28 horticulture programs not identified in the 1997 survey were found, but only two of these were confirmed to have been created since 1997. Overall, these data suggest a trajectory toward elimination of 2-year and certificate programs, and continued consolidation for 4-year degrees. If it continues, this trend is not favorable for the continued vitality of postsecondary horticulture programs in the United States and may impact progress negatively for the field of horticulture as a whole.
Megan Holmes and Tina M. Waliczek
The average cost of housing a single inmate in the United States is roughly $31,286 per year, bringing the total average cost states spend on corrections to more than $50 billion per year. Statistics show 1 in every 34 adults in the United States is under some form of correctional supervision; and after 3 years, more than 4 in 10 prisoners return to custody. The purpose of this study was to determine the availability of opportunities for horticultural community service and whether there were differences in incidences of recurrences of offenses/recidivism of offenders completing community service in horticultural vs. nonhorticultural settings. Data were collected through obtaining offender profile probation revocation reports, agency records, and community service supervision reports for one county in Texas. The sample included both violent and nonviolent and misdemeanor and felony offenders. Offenders who completed their community service in horticultural or nonhorticultural outdoor environments showed lower rates of recidivism compared with offenders who completed their community service in nonhorticultural indoor environments and those who had no community service. Demographic comparisons found no difference in incidence of recidivism in comparisons of offenders based on gender, age, and the environment in which community service was served. In addition, no difference was shown in incidence of recidivism in comparisons based on offenders with misdemeanor vs. felony charges. The results and information gathered support the continued notion that horticultural activities can play an important role in influencing an offender’s successful reentry into society.
Yuqi Li and Neil S. Mattson
Fertility management of seedlings and transplants is considered a key challenge in organic greenhouse production. This study was conducted to determine response of greenhouse-grown cucumber (Cucumis sativus) and nutrient release profile to two organic fertilizers and their combinations applied at three different concentrations in organic substrate. The organic fertilizers used were a turkey litter–based compost (TC) and a dairy manure vermicompost (VC). In addition, two control treatments [no fertilization (CK), conventional liquid fertilizer (CF)] were included. For TC, substrate leachate pH decreased for the first 17 days after addition and then increased, whereas electrical conductivity (EC), and calcium (Ca) and nitrate-nitrogen (NO3 −-N) concentrations increased and then declined. For VC, EC decreased continuously over time from days 0 to 52, whereas pH increased. The Ca and NO3 −-N concentrations decreased over time to 24 days and then did not change further. For TC/VC combinations, EC was stable for the first 17 days and then declined. For all organic fertilizer applications, potassium concentration was stable for the first 17 days and then decreased, whereas most of the sodium, ammonium-nitrogen, and chloride were no longer leached by 24 days. The VC and TC/VC combinations did not affect cucumber seed germination rate, seedling survival rate, seedling height, and leaf greenness (SPAD) as compared with CF. The stem length, leaf number, dry weight (DW), root index, and SPAD readings of cucumber transplants increased with increasing TC and VC fertilizer applications. The TC/VC combinations increased the biomass of cucumber transplants compared with CK, and did not differ from CF. The results of this study indicated that the 28.32 lb/yard3 of VC (high rate) or the 9.44 lb/yard3 of VC combined with 4 lb/yard3 of TC (medium rate) can be substituted for CF for the cultivation of cucumber seedlings. Based on DW, the 12 lb/yard3 of TC (high rate) or the 4 lb/yard3 of TC combined with 9.44 lb/yard3 of VC (medium rate) fertilizers were suitable replacements for CF for the cultivation of cucumber transplants.
Zhongjie Ji, James J. Camberato, Cankui Zhang and Yiwei Jiang
Plant growth regulators (PGRs) can mediate plant response to salinity stress. Perennial ryegrass (Lolium perenne) cultivars of BrightStar SLT, Catalina, Inspire, and SR4660ST were exposed to 0, 100, or 200 mm NaCl for 14 d. 6-benzyladenine (6-BA, 10 µm), γ-aminobutyric acid (GABA, 500 µm), nitric oxide (NO, 200 µm), and H2O were applied to the foliage every day for 3 days before stress and then every 2 days during salinity stress. Averaged across the four cultivars, a foliar spray of NO increased leaf fresh weight (FW) and dry weight (DW) at 0 mm NaCl, whereas application of 6-BA increased DW and GABA reduced Na+ concentration at 100 mm NaCl, compared with H2O application. Plants treated with 6-BA, GABA, and NO had less chlorotic and necrotic leaf tissue than plants treated with H2O at 200 mm NaCl. Spray of 6-BA and NO increased FW and DW, but application of all three PGRs maintained higher leaf photochemical efficiency and lower leaf Na+ concentration compared with H2O treatment at 200 mm NaCl. Across salinity and PGR treatments, ‘Catalina’ exhibited higher plant height than the ‘Inspire’ and SR4660ST, and SR4660ST had relatively higher Na+ concentration than ‘Catalina’ but not ‘BrightStar SLT’ and ‘Inspire’. The results demonstrate that 6-BA, GABA, and NO ameliorated salinity tolerance of perennial ryegrass by improving growth and photochemical efficiency or reducing Na+ accumulation.
Xiaofeng Yang, Lianzhu Chen, Ming Cao, Xuebin Zhang and Shaopeng Li
Nitrogen and potassium are two crucial nutrient elements that affect the yield and quality of crops. The aim of this study was to quantify the impacts of potassium on growth dynamics and quality of muskmelon, so as to optimize potassium management for muskmelon in a plastic greenhouse, and develop a coupling model of nitrogen and potassium. For this purpose, four experiments (two experiments with different levels of potassium treatment and planting dates, and the other two experiments with different ratios of nitrogen and potassium, and planting dates) on muskmelon (Cucumis melo L. ‘Nanhaimi’ and ‘Xizhoumi 25’) were conducted in a plastic greenhouse located at Sanya from Jan. 2014 to Sept. 2015. The quantitative relationship between leaf potassium content and growth dynamics and yield of muskmelon was determined and incorporated into a photosynthesis-driven crop growth model (SUCROS). Independent experimental data were used to validate the model. The critical leaf potassium content at the flowering stage for muskmelon ‘Nanhaimi’ and ‘Xizhoumi 25’ were 55.0 and 46.0 mg·g−1. The result showed that the coefficient of determination (r 2) between the predicted and measured values of leaf area index (LAI), direct weight of shoot (DWSH), direct weight of stem (DWST), dry weight of leaf (DWL), dry weight of fruit (DWF), fresh weight of fruit (FWF), soluble sugar content (SU), soluble protein content (PR), vitamin C (Vc), and soluble solids content (SO) of potassium model were 0.93, 0.98, 0.83, 0.96, 0.98, 0.99, 0.94, 0.94, 0.89, 0.85, and 0.90, respectively; and the relative root-mean-squared error (rRMSE) were 10.8%, 19.6%, 30.3%, 21.1%, 11.9%, 17.2%, 13.9%, 27.8%, 20.6%, and 10.1%, respectively. The two ways of nitrogen and potassium coupling (multiplicative coupling and minimum coupling) were compared, and the multiplicative coupling was used in model development finally. The r 2 between the predicted and measured values of LAI, DWSH, DWST, DWL, DWF, FWF, SU, PR, Vc, and SO of nitrogen and potassium coupling model were 0.78, 0.91, 0.93, 0.94, 0.83, 0.89, 0.92, 0.95, 0.91, and 0.93, respectively; and their rRMSE were 9.2%, 12.4%, 11.8%, 43.2%, 6.6%, 7.2%, 6.85%, 4.98%, 6.61%, and 4.35%, respectively. The models could be used for the optimization of potassium, nitrogen, and potassium coupling management for muskmelon production in a plastic greenhouse.
Jinwook Lee, In-Kyu Kang, Jacqueline F. Nock and Christopher B. Watkins
The effects of preharvest and postharvest treatments of 1-methylcyclopropene (1-MCP) in combination or alone on fruit quality and the incidence of physiological disorders during storage of ‘Fuji’ apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] at 20 and 0.5 °C were investigated. Preharvest 1-MCP (Harvista) treatments were applied 4 or 10 days before harvest (DBH), and then fruit were either untreated or treated with 1-MCP (SmartFresh) postharvest. Fruit were stored at 20 °C for up to 4 weeks or at 0.5 °C for up to 36 weeks. At harvest, starch pattern indices and watercore incidence and severity were lower in fruit with preharvest 1-MCP treatment applied 10 DBH than in untreated fruit and in fruit treated 4 DBH. At 20 °C, the combination of preharvest and postharvest 1-MCP treatments reduced the internal ethylene concentration (IEC) more than preharvest 1-MCP treatment alone, but not to a greater extent than postharvest 1-MCP treatment alone. Greasiness and watercore were reduced more by the combination of preharvest and postharvest 1-MCP treatments than by either treatment alone. However, preharvest and postharvest 1-MCP treatments, in combination or alone, did not consistently affect flesh firmness, titratable acidity (TA), soluble solids concentration, color a* values, or incidences of flesh browning, core browning, and stem-end flesh browning. At 0.5 °C, the combination of preharvest and postharvest 1-MCP treatments inhibited IECs and maintained firmness and TA more than no treatment or preharvest 1-MCP treatment alone. However, there was a lesser extent of differences than there was with postharvest 1-MCP treatment alone. Incidences of physiological disorders were not consistently affected by the preharvest and postharvest 1-MCP treatments. Overall, the results suggested that the preharvest 1-MCP treatment positively affected fruit quality attributes compared with no treatment during shelf life and long-term cold storage, but not as effectively as a combination of preharvest and postharvest 1-MCP treatments.
Thomas O. Green, John N. Rogers III, James R. Crum, Joseph M. Vargas Jr. and Thomas A. Nikolai
Results suggest that sand topdressing was more consistent at reducing dollar spot (Clarireedia jacksonii) in fairway turfgrass more so than rolling. This practice could be an effective cost-saving alternative to reduce frequent fungicide applications. Research was conducted from 2011 to 2014 on a simulated golf fairway and examined dollar spot severity responses in a mixed-stand of creeping bentgrass (Agrostis stolonifera) and annual bluegrass (Poa annua ssp. reptans) to sand topdressing and rolling. Treatments consisted of biweekly sand topdressing, rolling at three frequencies (one, three, or five times weekly), a control, and three replications. Infection was visually estimated. Sand topdressing significantly (P < 0.05) reduced disease up to 50% at the peak of the dollar spot activity in 2011, 2013, and 2014. Results on the effects of rolling on dollar spot were inconsistent.
Fan Li, Guoxian Wang, Rongpei Yu, Min Wu, Qinli Shan, Lifang Wu, Jiwei Ruan and Chunmei Yang
We investigated the effects of different planting seasons and gibberellic acid treatments on the growth and development of Gypsophila paniculata to explore new approaches to controlling the flowering period. Four different cultivars were selected and continually planted in July, September, and November in the low-latitude and high-altitude region of Kunming, China (25° N, 102° E). Results showed that the vegetative growth and flowering time of Gypsophila paniculata were prolonged and postponed when the planting time was delayed. Specifically, ‘My Pink’ showed 20% and 80% rosette rates when grown in autumn and winter, respectively, thus indicating that Gypsophila paniculata is sensitive to planting time. Moreover, GA3 treatment not only can significantly promote vegetative growth but also can stimulate early flowering and suppress the occurrence of rosettes during winter. This is more specific to ‘My Pink’, which showed 40% and 80% reductions in rosette rates with four and eight GA3 treatment applications, respectively. Our study showed that seasonal variations in the growth and development of Gypsophila paniculata and GA3 treatment can effectively stimulate early flowering and suppress rosettes during winter.
Mingxiu Liu, Peng Wang, Xu Wei, Qing Liu, Xiaolin Li, Guolu Liang and Qigao Guo
Triploid loquat (2n = 3x = 51) has stronger growth vigor and larger leaves, flowers, and fruit compared with its diploid parental plant (2n = 2x = 34), but the effects of triploidization on the contents of flavonoids and phenolics in leaves and flowers, which are the most important antioxidant compounds for pharmacological applications, have not been reported. In this report, 58 triploid loquat genotypes and seven corresponding diploid parental cultivars were used to evaluate the effects of triploidization on the contents of total flavonoids and phenolics and the antioxidant activities of leaves and flower buds. The results showed that the contents of total flavonoids and phenolics and their corresponding antioxidant activities were higher in most of the triploid loquat genotypes than their diploid parents. The antioxidant activities of leaves and flower buds were significantly correlated with the total flavonoids and phenolics contents in both diploid loquat and triploid loquat. It could be inferred that triploidization could increase the contents of flavonoids and phenolics in leaves and flower buds of loquat. Notably, the contents of total flavonoids and phenolics of leaves in triploid genotype ‘H3/24’ were the highest, reaching 212.00 mg rutin equivalent (RE)/g DW and 93.06 mg gallic acid equivalents (GAE)/g DW, respectively, which were significantly higher than those previously reported. Such a valuable trait may be stacked with other triploid traits that are already established, such as larger vegetative organs and better tolerance to various stresses, as a feasible strategy for breeding loquat cultivars with high pharmaceutical potency.