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Open access

Amanda J. Davis and Bernadine C. Strik

Soil amendment, mulching, and fertilization practices are key components of blueberry production, yet grower practices range widely and long-term impacts are not commonly studied. ‘Elliott’ northern highbush blueberry (Vaccinium corymbosum L.) was evaluated from establishment to maturity (2003–18) to investigate the impacts of pre-plant sawdust incorporation (with or without 141 m3·ha−1 sawdust incorporated into the bed area), sawdust mulch (with or without an 8-cm-deep layer on soil surface), and N fertilizer rate (low, medium, and high, increased incrementally from 22, 67, and 112 kg·ha−1 in 2004, respectively, to 56, 168, and 269 kg·ha−1 of N from 2010 to 2018). Soil with sawdust incorporated had 4.3% soil organic matter at the end of the study in 2018 compared with 3.4% for nonincorporated soil. Soil pH was higher with sawdust incorporation and mulch when plants were young, but by 2011 these treatments were similar. High rates of N fertilization decreased soil pH by 0.3 to 0.4 throughout the study compared with the low rate, but all treatments were within or above the recommended pH range (4.5–5.5) throughout the study. Low levels of N fertilization were associated with higher soil pH and lower leaf N in most years, but higher leaf Ca and often any impacts of the low N rate were mitigated when sawdust was incorporated. Soil and leaf Ca increased when sawdust was incorporated and used as a mulch and when fertilizing with the low rate of N, but fruit Ca concentration only increased with mulch and the low N rate, whereas levels decreased with incorporation. When sawdust was not incorporated before planting, N fertilization rate affected leaf N, Ca, S, and Mn concentration, whereas this was not found when soil was amended with sawdust. Unmulched plants generally had higher leaf N, K, Fe, and Al but lower leaf Ca compared with mulched. Sawdust incorporation increased yield 4% and produced fruit with higher total soluble solids (TSS), but similar firmness, on average (2008–13), than for unamended soil. There was no main effect of mulch on yield or berry traits; however, plants grown with sawdust incorporated and no mulch had 7% greater yield per plant (averaged over 2006–13) compared with incorporated with mulch or nonincorporated with or without mulch. Nitrogen fertilization rate had no effect on yield, but berry weight was greater with low or medium N rates, particularly when sawdust was not incorporated. Net returns from higher yield with sawdust incorporation more than compensated for the materials and labor costs. Berry firmness and TSS were similar among incorporation, mulch, and fertilizer treatments for most years. Incorporating sawdust before planting resulted in an estimated $7680/ha greater net profit from fruit sales during the study period, more than compensating for the initial materials and application cost ($3150/ha). Use of the low rate of N from 2004 to 2018 saved $2680/ha and $5152/ha compared with the medium and high rates, respectively.

Open access

Dilip R. Panthee and Randy G. Gardner

‘Mountain Bebe’ is the F1 hybrid of NC 7 Grape × NC 8 Grape. It is resistant to late blight (Ph-2 and Ph-3 genes), tomato spotted wilt virus (Sw-5 gene), and fusarium wilt races 2 and 3 (I-2 and I-3 genes). The hybrid has a compact, indeterminate growth habit with short internodes (br gene). It has total soluble solids equal to ‘Mountain Honey’ with dark red fruits of ≈11.7 g per fruit.


‘Mountain Bebe’ (tested as NC10259) is the F1 hybrid of NC

Open access

Wenqian Zhang, Xiaoling Jin, Donglin Zhang, Minhuan Zhang, and Wen Xing

Zelkova schneideriana Hand.-Mazz. is a member of Ulmaceae (elm family), and is valued for its beautiful habit (up to 30 m in height and about 100 cm at diameter at breast height), huge crown, and gorgeous foliage (Dirr, 2010). It is widely distributed in southern China, although with very limited individuals and is listed as an endangered species (eFlora, 2020; Naciria et al., 2019). Its high-density wood is hard and elastic, which is in demand for high-quality furniture and other special uses. Zelkova is famous for its valuable timber and its

Open access

Paul C. Bartley III, Aziz Amoozegar, William C. Fonteno, and Brian E. Jackson

The heterogeneity of horticultural substrates makes basic physical characteristics, such as total porosity and particle density, difficult to estimate. Due to the material source, inclusion of occluded pores, and hydrophobicity, particle density values reported from using liquid pyknometry, vary widely. Gas pycnometry was used to determine the particle density of coir, peat, perlite, pine bark, and wood substrates. Further precision was examined by gas species and separation by particle size. The calculated particle densities for each material determined by He, N2, and air were relatively constant and varied little despite the species of gas used. Particle size affected the measured particle density of perlite and pine bark but was minimal with coir, peat, and wood. Reducing the particle size removed more occluded pores and the measured particle density increased. Given the small variability, the use of particle density values obtained by gas pycnometry provides repeatable, precise measurements of substrate material total porosity.

Open access

Ian K. Atkins and Jennifer K. Boldt

Supplemental lighting, temperature control, and CO2 enrichment can improve the productivity of greenhouse crops, but operating costs for greenhouse control systems to maintain environmental parameters at desired setpoints can be expensive. To balance operating costs with productivity, growers need to be able to predict how a crop will perform as a function of photosynthetic photon flux density (PPFD), CO2 concentration, and temperature. The objective of this study was to explore the response of net photosynthetic rate (Pn) to PPFD and CO2 concentration, for plants acclimated to different growth environment temperatures or light intensities. We measured Pn at all combinations of 14 irradiances and four CO2 concentrations of calibrachoa (Calibrachoa ×hybrida ‘Superbells Lemon Slice’), petunia (Petunia ×hybrida ‘Supertunia Mini Strawberry Pink Veined’), and verbena (Verbena ×hybrida ‘Superbena Royale Whitecap’) grown at three light intensities, and of geranium (Pelargonium ×hortorum ‘Maverick Red’), pepper (Capsicum annuum ‘California Wonder’), and sunflower (Helianthus annuus ‘Pacino Gold’) grown at three different temperatures. Sunflower, pepper, and geranium were fit to a model representing Pn as a function of PPFD, CO2 concentration, and leaf temperature. Photosynthetic light response curves, at each CO2 concentration, were fit for each species and growth environment using a nonrectangular hyperbola. These models can be used to identify multiple combinations of PPFD, CO2 concentration, and leaf temperature that would result in equivalent rates of photosynthesis, allowing the most cost-effective combination to be chosen.

Open access

Zienab F.R. Ahmed, Navjot Kaur, Sajid Maqsood, and Guillermo Schmeda-Hirschmann

The ‘Khenizi’ date palm is one of the most recognized date palm cultivars. It is commonly consumed at the Bisr, Rutab, and Tamr stages of ripening; however, the fruit has a short shelf/storage life at this stage of maturity even with refrigeration. Preharvest application of a natural elicitor chitosan (Ch) has been reported to have positive influences on quality and shelf life of many fruits; however, synergetic effects of Chand other natural elicitors have not been investigated. Therefore, this study aimed to investigate the synergistic effect of preharvest spray treatments with Ch 1% in combination with calcium chloride (Ca) 3% and salicylic acid (SA) 2 mm on ‘Khenizi’ date fruit quality and storage life. Fruit quality parameters, including physical and physiochemical characteristics, phytochemical content, and bioactive properties, were determined at harvest time and during cold storage at 2 °C for 60 days for 2 months. Our results revealed that a combination of these elicitors had significantly influenced the fruit quality during storage compared with control. For instance, Ch+SA and Ch+Ca+SA treatments improved total phenolic content (TPC), and the antioxidant activity at harvest and at specific times during the postharvest storage period. Furthermore, Ch+SA+Ca treatment significantly delayed senescence in treated fruits during cold storage for 45 days as compared with other treatments and the control. In addition, Ch+Ca-treated fruits had the lowest weight loss after 45 days of cold storage. Ch+SA treatment had the lowest microbial counts as compared with other treatments, including the control. The significance of this study is that it provides evidence that a combination of these elicitors has the potential to improve fruit quality at harvest, as well as during postharvest storage Future studies should be directed to fine tune the concentrations and combinations that may have commercial applications.

Open access

Yunfei Mao, Yijun Yin, Xueli Cui, Haiyan Wang, Xiafei Su, Lulu Zhang, Xin Qin, Yangbo Liu, Yanli Hu, and Xiang Shen

David’s peach [Prunus davidiana (Carrière) Franch], a member of the Rosaceae family, is a tree with strong environmental adaptability that prefers high light; tolerates cold, drought, and low nutrient conditions; and exhibits sensitivity to waterlogging (Zhang et al., 2019). It is distributed mainly in Shandong, Hebei, Henan, Shanxi, Shaanxi, Gansu, Sichuan, and Yunnan provinces in China (Zheng et al., 2014). It grows between 800 and 3200 m above sea level (Guan et al., 2014; Li et al., 2014). It is used primarily in North China as an ornamental plant and

Open access

William B. Miller, Wanxiang Lu, and Dongqin Tang

Although ethephon is commonly used as a plant growth regulator during commercial production of horticultural crops, information on its movement within plants is limited. In this study, we developed a method to detect ethephon in plant tissues, and determined ethephon localization and movement using tomato (Solanum lycopersicum L.) as a model system. Tissues were ground in an acidic buffer that preserved ethephon intact. Ethylene was released from the extracts by adding sodium hydroxide and was determined subsequently by gas chromatography. Ethephon was detected in leaves within 1 hour of application to peat-based root zones and within 10 minutes in hydroponics. In a pulse–chase experiment, ethephon levels increased initially, then decreased after the plants were returned to ethephon-free solutions. Ethephon was present in directly collected xylem fluid; fluid collected from petiole stumps (after leaf blade excision) had similar ethephon levels between the different petioles. Stem girdling had no effect on ethephon accumulation in leaves. Together, these data indicate ethephon is readily mobile in the xylem stream and provides insight into the commercial use of ethephon as a root zone-applied growth regulator.

Open access

Job Teixeira de Oliveira, Fernando França da Cunha, Rubens Alves de Oliveira, and Catariny Cabral Aleman Pina

Path coefficient analysis has been widely used to understand production better and determine the relationships between fruit and their constituents. This study evaluated the correlations between mass and other physical characteristics, and contributes to selecting cape gooseberry fruit. The attributes assessed were the total mass of the cape gooseberry fruit (TM) (fruit mass with husk), fruit mass (FM) (fruit mass without husk), husk mass (HM), husk length (HL), the largest transverse husk diameter (LD), fruit diameter (FD), and color of the husk (CH). Using path analysis, it was possible to verify directly that, among the physical components of the study, TM and FD have a direct and positive influence on FM. Fruit mass had a direct and negative correlation with HM, indicating that fruit with the heaviest husk (and green color) have not yet reached full maturation, nor reached their greatest mass. This result suggests that TM is strongly indirectly influenced by the HL, husk diameter, HM, and FD.

Open access

Zanzan Li, Jinyu Hu, Hang Tang, Liping Cao, Yuhang Chen, Qiaosheng Guo, and Changlin Wang

The spicas of Prunella vulgaris are widely used in the medical, beverage, and ornamental fields. Temperature and photoperiod are the two main ecological factors that determine the transformation of many plants from vegetative growth to reproductive growth. To explore the response of P. vulgaris flowering to temperature and photoperiod induction, we adopted vernalization long-day, vernalization short-day, nonvernalization long-day, and nonvernalization short-day treatments. The results showed that the morphology (total number of leaves, number of branches, number of leaves per branch, and branch length) of the vernalization treatment groups was significantly different from that of other nonvernalization groups, and the photosynthetic pigments, net photosynthetic rate, water use efficiency, stomatal conductance, intercellular CO2 concentration, and transpiration rate increased in the vernalization treatment group. However, the gibberellin 3 (GA3), indole-3-acetic acid and zeatin riboside (ZR) contents were significantly increased under the short-day treatments groups, and the results were the same for the expression of endogenous hormone synthesis genes, except for abscisic acid (ABA). The flowering-related genes soc1, elf3, svp, ga20ox, and cry1 were highly expressed under the vernalization short-day. Therefore, the induction of vernalization is more conducive to the increase in the photosynthetic rate. Temperature and photoperiod synergistically induced the synthesis and accumulation of starch, sugar, amino acids, and protein and affected the content of endogenous hormones and the expression of genes involved in their synthesis. GA3 and ZR had thresholds for their regulation of the flowering process in P. vulgaris, and high concentrations of ABA promoted flowering. Temperature and photoperiod coordinate the expression of the flowering-related genes soc1, elf3, svp, ga20ox, and cry1, thereby affecting the flowering process in P. vulgaris.