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Open access

Jingjing Kou, Zhihui Zhao, Wenjiang Wang, Chuangqi Wei, Junfeng Guan and Christopher Ference

‘Mopan’ persimmon (Diospyros kaki Thunb.) is a traditional astringent cultivar of persimmon and ‘Yoho’ persimmon (D. kaki) is a newly introduced Japanese nonastringent type of cultivar in northern China. Studies were conducted to investigate the physiological changes and expression of ripening-related genes in the postharvest process at different periods under the effects of endogenous ethylene in both cultivars. Persimmons were harvested and stored under room temperature for 20 days. An analysis of physiological changes showed significant differences between the two cultivars. Total soluble solids declined in ‘Mopan’ fruit, whereas those in ‘Yoho’ fruit increased during storage. Firmness, color, index of absorbance difference, total and soluble tannin contents, ethylene production, and respiration rates showed the same trend, but these values vary by cultivar. ‘Mopan’ fruit softened rapidly after harvest and attained edible quality in 20 days, with an increased rate of softening accompanied by increased expression of ripening-related genes. In contract, ‘Yoho’ fruit softening occurred slowly and did not soften even after 20 days, with minimal accumulation of the ripening-related genes. The information obtained from this study demonstrates that cell wall-hydrolyzing enzymes, the de-astringent process, and endogenous ethylene have critical roles in postharvest ripening, gene expression, and physiological property changes of ‘Mopan’ and ‘Yoho’ persimmon fruit during storage.

Open access

Guoqiang Wang, Ping Qu, Hongying Huang, Guofeng Wu and Haijun Yan

To produce a firm and cohesive root plug to promote automated transplanting of nursery-grown seedlings, hydrolyzed soy protein-modified urea–formaldehyde (H-UF) resins were used to bind renewable substrate [mixture of coconut (Cocos nucifera) coir dust, coconut fiber, organic manure, perlite, vermiculite]. The resulting substrate block showed high density and nutrient concentrations in the peripheral portion and relatively low density and nutrient levels in the center. The porosity of the H-UF/substrate block was slightly lower than that of standard substrate. The electrical conductivity and pH were beneficial for germination and early seedling development. The modified resins in the substrate block existed in the form of spheres that adhered to each other and formed a porous structure from nano- to micrometer scale. In particular, the H-UF/substrate block increased the seedling height, stem diameter, root length, and leaf area of ‘Sujiao No. 5’ pepper (Capsicum annum) seedlings by 56.07%, 43.33%, 1.33%, and 89.63%, respectively, compared with those of seedlings grown in substrate without H-UF resin. The contents of nitrogen, phosphorus, and potassium in the shoot and root of pepper seedlings grown in H-UF/substrate blocks were enhanced by 39% to 69% compared with those of seedlings grown in standard substrate. The compressive strength of the H-UF/substrate block was 3.6-fold higher than that of substrate when 50% resin was added to the substrate. The results indicated that a combination of the substrate with the modified resin was suitable as a growth substrate for nursery production of pepper seedling plugs.

Open access

Patrick H. Kingston, Carolyn F. Scagel, David R. Bryla and Bernadine C. Strik

Peat and coir are commonly used for substrate production of highbush blueberry (Vaccinium sp.). Perlite is also typically added to improve drainage and stability of the media. The purpose of the present study was to determine how various combinations of each affect growth and nutrition in highbush blueberry. Two cultivars, ‘Liberty’ northern highbush blueberry (V. corymbosum L.) and ‘Jewel’ southern highbush blueberry (interspecific hybrid of V. corymbosum L. and V. darrowii Camp.), were grown for 3 months in media containing 0%, 10%, 20%, or 30% perlite, by volume, and a 1:0, 2:1, 1:2, or 0:1 ratio of peat and coir. At 95 days after transplanting, total dry weight of the ‘Liberty’ plants was greatest in pure peat and progressively less as more coir or perlite was added to the media. Total dry weight of ‘Jewel’ also declined with increasing amounts of perlite but, in this case, was unaffected by the ratio of peat and coir. The response of the plants to perlite did not appear to be a function of pH or nutrition and was most likely related to the effects of perlite on media water relations. Response to peat and coir, on the other hand, may have been due to nutrition and salinity of the media. In both cultivars, a higher amount of peat in the media improved uptake of N, P, Mg, and S and decreased uptake of K, B, Zn, and Na. Coir, on the other hand, contained higher concentrations of Na and Cl than peat. These findings suggest that the use of high amounts of perlite in the media could be detrimental when growing highbush blueberry in substrate, and some cultivars may grow better in peat than in coir.

Open access

Juan J. Polari, Louise Ferguson and Selina C. Wang

Moisture and fat content, fatty acid profile, and volatile terpenes were measured for the first time for ‘Kalehghouchi’, ‘Pete 1’, and ‘Lost Hills’ pistachios grown at two California microclimates: Lost Hills and Parlier. ‘Kalehghouchi’ had the highest moisture content, followed by ‘Pete 1’ and ‘Lost Hills’, respectively. While the moisture content of ‘Kalehghouchi’ was not significantly affected by location, it was lower for ‘Pete 1’ grown at Parlier (40.8 vs. 40.8 g/100 g) and higher for ‘Lost Hill’ grown there (48.2 vs. 45.2 g/100 g). ‘Pete 1’ grown at the Parlier site had a higher fat content compared with ‘Lost Hills’ (47.7 vs. 43.0 g/100 g). ‘Kalehghouchi’ had a lower fat content at Parlier compared with Lost Hills (42.0 vs. 44.9 g/100 g), and ‘Lost Hills’ was unaffected by location. The main fatty acid measured in the pistachio samples was oleic acid (52% to 58%), followed by linoleic (26% to 33%) and palmitic acids (11% to 13%). While oleic acid content of ‘Lost Hills’ and ‘Kalehghouchi’ was higher for pistachios grown in Parlier, no impact of location was observed for ‘Pete 1’. The fatty acid profiles of all three cultivars appeared to be more dependent on genotype and less affected by microclimate. α-pinene (95–1682 ng/kg), limonene (37–741 ng/kg), and α-terpinolene (1–368 ng/kg) were the most abundant volatiles among all the cultivars and locations. Microclimate was the primary factor in determining volatile terpenes concentration in pistachio kernels.

Open access

Paul W. Bosland and Danise Coon

Open access

Xuan Wei, Hayk Khachatryan and Alicia Rihn

In recent years, growers in the ornamental horticulture industry have experienced declining revenue and shrinking profit margins due to increased consumer spending captured by wholesale stores bypass, price competition at the retail level, as well as relatively low consumer demand. Maintaining cost-effective production practices is critical for nursery and greenhouse growers to stay profitable. However, a recent trend to impose more restrictive labeling polices on pesticide use (i.e., disclosing the use of neonicotinoids) may impact growers’ already tightening production costs. A better understanding of the cost structure and production decision-making can provide insights for profitable operation. Using a partial enterprise budgeting approach, this research aims to evaluate production costs and profitability for 20 individual greenhouse annual and perennial crop production systems. Three primary economic performance indicators (net income, gross margin, and profit margin) were calculated and a sensitivity analysis was conducted to account for potential risks in production. Our results suggest that production costs vary significantly among different crops, thus implying that producers may have different profitability levels depending on the combination of crops grown. Our partial enterprise budgeting estimates serve as a reference point and can assist producers with reducing costs in specific areas, and aids in selecting and adjusting crop combinations to maximize potential profits. Sensitivity analysis scenarios provide insights to producers for evaluation of their entire operations and aid in making decisions on adopting alternative practices.

Open access

Job Teixeira de Oliveira, Rubens Alves de Oliveira, Mario Puiatti, Paulo Teodoro and Rafael Montanari

The objective of this study was to evaluate whether the spatial variability of plant production components and the use of an irrigation and fertirrigation management system with controlled deficit affect the yield and incidence of garlic lateral shoot growing (LSG). An analysis of these data through statistical and geostatistical techniques made it possible to verify that the increase in yield is directly related to the height and diameter of the bulb and that the lateral shoot growing is directly related to the increase in yield. Lower water depths and lower nitrogen doses applied during clove differentiation imply a lower incidence of LSG, whereas increased irrigation and fertigation with nitrogen results in lower bulb volumes.

Open access

Andrés Javier Peña Quiñones, Melba Ruth Salazar Gutierrez and Gerrit Hoogenboom

A common problem for decision makers in selecting frost control options is uncertainty about the level of injury that can be caused by low temperatures. During the past few years, the concept of lethal temperature (LT) at which 10% of the bud population dies (LT10) has been used as an index for evaluating the vulnerability of flower buds to low temperature conditions. This concept has shown to be a useful tool for frost control decision-making. However, the current methods used to obtain LT values assume no spatial or temporal variability, which results in a high level of uncertainty. The goal of this study was to develop an approach that decreases the uncertainty based on the known effects of temperature on bud vulnerability. A growth chamber experiment was conducted to determine flower bud vulnerability to low temperature as a function of temperature. The results from this study showed that thermal time expressed in degree days could explain changes in floral bud development and vulnerability to frost injury. According to our findings, LT10 is a fully acceptable index for determining flower bud vulnerability to low temperatures in orchard crops. Based on this information, we found that among the five apple and cherry cultivars analyzed, ‘Gala’ is the least vulnerable to low temperature because it starts at the beginning of spring with a high level of hardiness and increases its vulnerability at a low rate. The approach described in this article may enhance decision-making certainty associated with the timing and methods to increase air temperature in orchards during low-temperature events to avoid frost damage.

Open access

Elisa Solis-Toapanta, Andrei Kirilenko and Celina Gómez

Social media platforms such as Reddit, centered on user-generated, anonymous discussions, can facilitate the exchange of information and resources across niche online communities known as “subreddits.” Using data mining tools and content analysis methods, our objectives were to identify recurring questions and characterize comment (“response”) accuracy from four subreddits focused on hydroponic indoor gardening (r/hydro, r/Hydroponics, r/UrbanFarming, and r/Aerogarden). A total of 1617 original posts (OPs) were classified into one of ten topics and 4891 primary responses were analyzed for accuracy. The three topics with the most OPs (production systems, plant lighting, and root-zone environment), which accounted for 50% of the total OPs, were subcategorized and inductively analyzed. Most posts in the analyzed subreddits related to confusion regarding the design and implementation of appropriate hydroponic production systems. In addition, misinformation about plant lighting is a major part of discussions about growing plants indoors. There are also knowledge gaps regarding nutrient solution management, particularly about fertilizer formulation, pH balance, and on the impact that solution temperature has on plant growth and development. In general, there were no differences among response accuracy for all topics included in our analysis. However, regardless of topic, responses for most OPs had less than 50% accuracy, which demonstrates that misinformation can be disseminated in social media platforms such as Reddit. As suggested by the results of this study, targeted, open access research and outreach efforts offer an opportunity to address knowledge gaps among consumers interested in indoor gardening.