Patrick J. Conner
‘Kalos’ is a new pecan (
Azeezahmed Shaik, Hardeep Singh, Sukhbir Singh, Thayne Montague, and Jacobo Sanchez
Demand for locally produced, organically grown leafy greens is increasing throughout the United States. However, due to lack of efficient organic fertilizers (OFs) for soilless substrates, organic greenhouse production of leafy greens may be challenging. Therefore, a greenhouse study was conducted to analyze the effects of six liquid OFs on growth and development of lettuce in a soilless system. Two experiments were conducted using a randomized block design, and treatments included six fish- or plant-based OFs: OF1 (5N–1P–1K), OF2 (2N–5P–1K), OF3 (3N–1P–1K), OF4 (2N–2P–2K), OF5 (4N–1P–1K), and OF6 (3N–3P–2K); one inorganic fertilizer treatment (IF, 24N–8P–16K); and one unfertilized control treatment. Fertilizer solutions were prepared at 2 dS⋅m–1 and applied at 100 mL/plant. In Expt. 1, fresh biomass for IF-treated plants was 12% to 38% greater than OF treatments, whereas this difference ranged from 25% to 57% in Expt. 2. Similarly, leaf area values of IF-treated plants were 5% to 40% greater than OF treatments in Expt. 1, and the difference ranged from 28% to 90% in Expt. 2. A possible explanation could be greater availability of nutrients in the IF treatment compared with OF treatments. There was no significant difference among fertilized treatments for number of leaves and stem diameter. Based on the index-based ranking, fish-based (OF1) and fish- and plant-based (OF2 and OF6) performed well among different liquid OFs used in the study. Although the yield under OFs was less compared with that under IF, there is potential to reduce this yield gap by optimized fertility management of these fertilizers. Future research is needed to investigate the impact of optimized rate, timing, different placement, and additional nitrogen (N) sources of OFs on the soilless production of lettuce.
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.
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 (
‘Mountain Bebe’ (tested as NC10259) is the F1 hybrid of NC
Wenqian Zhang, Xiaoling Jin, Donglin Zhang, Minhuan Zhang, and Wen Xing
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.
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.
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.
Yunfei Mao, Yijun Yin, Xueli Cui, Haiyan Wang, Xiafei Su, Lulu Zhang, Xin Qin, Yangbo Liu, Yanli Hu, and Xiang Shen
David’s peach [