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Qiang Zhu, Yuncong C. Li, Rao S. Mylavarapu, Kelly Morgan and Mingjian Geng

Preplant soil testing is essential for optimizing phosphorus (P) fertilization and minimizing the potential for soil P losses. Currently, there is no effective soil P extractant for calcareous soils in Florida. This study was conducted to compare Mehlich-3, ammonium bicarbonate–diethylenetriaminepentaacetic acid (AB-DTPA), and Olsen for evaluating P availability, estimating soil-test P (STP) critical levels, and calibrating P application rates for fresh-market tomato (Solanum lycopersicum L.) production in a calcareous soil. Tomatoes were grown during Winter 2014 and 2015 with P application rates of 0, 29, 49, 78, 98, and 118 kg·ha‒1 P. Water-extractable P (water-P) and dissolved reactive P (DRP) in leachate were used to determine the STP change point of leaching potential. Results showed the greatest correlation occurred between Mehlich-3 and Olsen of the three STP extractants. For Mehlich-3-P, the medium STP level (producing 75% to 90% relative yield) was predicted from 76 to 89 mg·kg‒1 and the change point was predicted at 88 or 104 mg·kg‒1 by split-line models. The P requirement was calculated from 52 to 112 kg·ha‒1 when Mehlich-3-P was rated as low level (producing 50% to 75% relative yield), which was from 42 to 76 mg·kg‒1. The multiple regression models using AB-DTPA-P and Olsen-P could not predict either the medium STP level or the practical P application rates for the low level. Consequently, based on 2 years of data, Mehlich-3 was the most effective extractant for estimating soil P availability and calibrating P rates in calcareous soils with an extremely high calcium carbonate (CaCO3) content.

Open access

Travis R. Alexander, Thomas S. Collins and Carol A. Miles

‘Brown Snout’ cider apple (Malus ×domestica) is desired by cider makers for its relatively high levels of phenolics, and over-the-row machine harvesting of ‘Brown Snout’ has been demonstrated to provide similar yield to hand harvest at a significantly lower cost. The purpose of this study was to determine if there is a measurable impact of harvest method on the phenolic profile of ‘Brown Snout’ juice and cider to better inform equipment adoption recommendations. Using a redox titration assay, the titratable tannin content (± SE) of juice (0.19% ± 0.01%) and cider (0.19% ± 0.01%) were found not to differ due to harvest method. Using a protein precipitation assay, juice from machine-harvested fruit was found to have lower levels of total tannins [231 ± 36 mg·L−1 catechin equivalents (CE)] than juice from hand-harvested fruit (420 ± 14 mg·L−1 CE). However, the total tannins of cider did not differ due to harvest method, the overall average for machine and hand harvest was 203 ± 22 mg·L−1 CE. The total phenolics of juice and cider did not differ due to harvest method (1415 ± 98 mg·L−1 CE and 1431 ± 73 mg·L−1 CE, respectively). Discriminant analysis based on an average of 33 tentatively identified phenolic compounds, as measured by ultra-high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry, showed no separation due to harvest method in juice or cider. In conclusion, over-the-row machine harvesting of ‘Brown Snout’ resulted in a final product of similar quality at reduced labor costs, and thus shows potential for increasing the commercial sustainability of cider apple operations.

Open access

Alba J. Collart, Stephen L. Meyers and Jason K. Ward

Skinning of sweetpotato (Ipomoea batatas) storage roots is one of the greatest concerns of sweetpotato producers. Although skinning injury is very common, the severity of the injury can vary widely. At an undefined threshold, sweetpotatoes with skinning injury are no longer sold for fresh consumption. The objectives of this study were to examine how skinning injury influences consumers’ willingness-to-pay (WTP) for sweetpotatoes and to identify differences in valuations when the extent of skinning injury is labeled. Image analysis was used to quantify skinning injury and then an incentive-compatible, nonhypothetical laboratory experimental auction was conducted to collect data on consumers’ WTP for five categories of sweetpotatoes: 0% to <1% skinning injury, 1.0% to 3.0%, 3.1% to 5.0%, 5.1% to 7.5%, and 7.6% to 10.0%. On average, consumers were willing to pay the most for sweetpotatoes with 0% to <1% skinning injury (up to $1.51/lb to $1.67/lb) and the least for sweetpotatoes with 7.6% to 10% (up to $0.76/lb to $0.85/lb), yet mean WTP values were nonzero for all skinning levels. Moreover, when the extent of skinning was labeled (relative to when they bid blindly), consumers were willing to pay price premiums for sweetpotatoes with low skinning injury levels (0% to 5%) and discounted sweetpotatoes with the highest skinning injury level (7.6% to 10.0%), suggesting that skinning levels of 7.6% and above may not be acceptable by consumers.

Open access

Elsa Sánchez, Maria Gorgo-Gourovitch and Lee Stivers

Hispanics residing in the United States are playing a larger role in agriculture. For example, in Pennsylvania, this group comprises the largest increase in new farmers, according to the 2012 Census of Agriculture. Efforts to connect with this population can be improved. Hispanic farmers and farmworkers face access barriers to agricultural programming that need to be addressed to more effectively “reach and teach.” Over a 1-year period, 22 to 25 agricultural educators attended a three-workshop training series focused on increasing knowledge and skills for planning, designing, advertising, and delivering agricultural programs inviting to Hispanic farmers and farmworkers. The workshop series included an expert on the science of inclusion, a specialist in Latino community studies, and several representatives from organizations with long histories of connecting with Hispanic farming audiences. Through guided activities and facilitated discussion, participants developed strategies for creating programming welcoming to the Hispanic farming community. This workshop series was highly rated by participants. After the first workshop, one participant stated that it was the best diversity workshop he had attended in his 22-year career. In a follow-up survey 1 year after the final workshop, the majority of respondents had made efforts to build relationships through agricultural programming for Hispanic farmers and farmworkers. Here, we are providing the methods we employed to serve as a model for others working to connect with this or other underserved or nontraditional farming audiences.

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Chen-Yu Lin, Kan-Shu Chen, Hsuan-Ping Chen, Hsiang-I Lee and Ching-Hsiang Hsieh

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.

Open access

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.

Open access

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.

Open access

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.

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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.

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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.