In Hawaii, the commercial papaya industry is based on cultivars that segregate as females or hermaphrodites. Multiple seedlings are planted and then thinned at flowering to single hermaphrodites at each site. The aim of this study was to increase propagation efficiency by improving our procedure for micropropagation of hermaphrodite plants only. Initially, shoots were multiplied in vented jars on M2 medium, a Murashige and Skoog formulation containing 0.25 μM 6-benzyladenine (BA) and 0.1 μM α-naphthalene acetic acid (NAA). At weekly intervals, micropropagated shoots were either incubated for 4 to 7 days in IBA2 medium containing 20 μM indole-3-butyric acid (IBA) or were dipped in autoclaved rooting powder containing 0.8% IBA (DIP); then, they were placed in M2 until root initials or small roots were visible. After root induction in both treatments, plants were transferred to an in vitro medium containing ½ MSO and 30 g⋅L−1 sucrose in vermiculite (VER). The IBA2 treatment produced 467 potted plants compared to 475 produced by the DIP treatment; however, the average number of days that each treatment required from root induction to potting of rooted plants was not significantly different (IBA2: 52.42 ± 5.65 days; DIP: 51.94 ± 3.61 days). Plants from both treatments were grown in either wet potting medium (500 mL water/300 g potting medium) or damp potting medium (120 mL water/300 g potting medium) to test the effect of moisture content on plant survival and growth after potting. Use of damp rather than wet potting medium resulted in significantly higher plant survival and growth. These results could facilitate more efficient commercial practice for papaya growers.
Maureen M. M. Fitch, Mary Joy Ancheta, Luyen C. Huynh, Xiaoling He, Marjorie A. Ortega, Hideko K. Fields, Carol M. Murakami, Josienellie R. Shaw, and Jeremiah-James Lopez
Seon-Ok Kim, Su Young Son, Min Ji Kim, Choong Hwan Lee, and Sin-Ae Park
Mycobacterium vaccae is a species of nonpathogenic bacterium that lives naturally in soil. This study compared the physiological effects at a metabolomic level with autonomic nervous system responses in adults during soil-mixing activities, based on the presence or absence of M. vaccae in the soil. Twenty-nine adult participants performed soil-mixing activities for 5 minutes using sterilized soil with culture media and M. vaccae, respectively. Blood samples were drawn twice from each participant after each activity. Electroencephalograms and electrocardiograms were measured during the activity. Serum metabolites underwent metabolite profiling by gas chromatography, followed by multivariate analyses. Soil-emitted volatile organic compounds were identified using the solid-phase microextraction and gas chromatography-mass spectroscopy, followed by multivariate analyses. The volatile compound analysis revealed that the metabolites related to esters and sulfur-containing compounds are greater in soil with M. vaccae. Serum metabolomics revealed that the treatment group (soil inoculated by M. vaccae) possesses relatively higher levels of inter-alia organic and amino acids compared with the control group (soil mixed with culture media). In the treatment group, the electroencephalogram and electrocardiogram revealed that alpha band activity of the occipital lobe increases, while heart rate decreases. This study concludes that M. vaccae soil contact can affect human metabolic and autonomic reactions.
Bo Wang, Weimin Wu, Xicheng Wang, Zhuangwei Wang, and Yaming Qian
Muscadine grape (Vitis rotundifolia) is highly resistant to many diseases and insects that attack european grape (Vitis vinifera). However, distant hybridization incompatibility between V. rotundifolia (female) and V. vinifera (male) impedes the utilization of V. rotundifolia in grape breeding. This study used fourth-dimension label-free protein quantitation to detect the key genes and pathways in the V. rotundifolia stigma after self-pollination (V. rotundifolia × V. rotundifolia) and cross-pollination (V. rotundifolia × V. vinifera). A histological analysis showed that pollen tube growth in the stigma of V. rotundifolia was arrested 8 hours after cross-pollination, but not after self-pollination. A proteomic analysis identified 32 differentially expressed proteins (DEPs) in the stigma of V. rotundifolia between self-pollination and cross-pollination. A heatmap analysis grouped these DEPs into four clusters. The top gene ontology terms were ATPase-coupled transmembrane transporter activity, extracellular region, DNA replication, and cellular carbohydrate biosynthetic process. A Kyoto Encyclopedia of Genes and Genomes analysis revealed that these DEPs participated in DNA replication and starch and sucrose metabolism pathways. The downregulated A5AY88, D7TJ35, D7SU26, F6HJI1, and F6GUE7 may have a role in cross incompatibility. This study revealed the cross incompatibility of grapes at histological and proteomic levels.
Azlan Zahid, Md Sultan Mahmud, Long He, James Schupp, Daeun Choi, and Paul Heinemann
Todd P. West, Gregory Morgenson, and Connor C. Hagemeyer
‘EmerDak’ is a new cultivar of
Allen V. Barker
The book has fifteen chapters covering the topics in the global nitrogen cycle, the use of nitrogen-containing fertilizers, and the effects of fertilizer use on the environment of the World. Each chapter is an independent one, and the text is not divided into sections of related topics. The chapters cover general topics of management of nitrogen in soil and specific topics in management of nitrogen in geographic regions of the World.
Claudia Moggia, Yeldo Valdés, Alejandra Arancibia, Marcelo Valdés, Catalina Radrigan, Gloria Icaza, Randolph Beaudry, and Gustavo A. Lobos
Fresh fruit from northern highbush blueberry (Vaccinium corymbosum) and rabbiteye blueberry (Vaccinium ashei) are highly perishable, so reaching distant markets while maintaining superior quality and value is a challenge. Although firmness is one of the most critical traits of blueberries (Vaccinium sp.), most of the industry relies on a subjective-tactile assessment or on the use of low-cost texture analyzers, whereas scientists tend to rely on the FirmTech II instrument. In the present study, the FirmTech II was evaluated as a texture analyzer and compared with tactile estimation, two other FirmTech II devices, and three relatively inexpensive durometers (Penefel, Durofel, and DM1600). Tests were run for fruit previously segregated by tactile (T) measurements into three classes of firmness: Soft-T, Moderate-T, and Firm-T; fruit were classified into instrument-based (I) categories of texture: Soft-I, Moderate-I, and Firm-I using the FirmTech II instrument. The level of coincidence between T and I assessments were higher in the soft (90.7% to 92.6%) and moderate (69.6% to 78.2%) classes compared with the firm class (51.6% to 61.4%). Among firmness categories, T and I assessments tended to agree; none of the Soft-T fruit were classed as Firm-I. In comparisons between equivalently calibrated FirmTech II devices, concordance always decreased as fruit firmness increased, indicating that more reproducible readings for a given instrument could be expected from softer fruit. Dual measurements on a single fruit for FirmTech II and a second device yielded variable, but significant correlation coefficients (Penefel: r 2 = 0.61 to 0.67; Durofel: r 2 = 0.48 to 0.61; DM1600: r 2 = 0.08 to 0.49). The highest correlation existed between two FirmTech II devices (r 2 = 0.94 to 0.95). However, correlations between the FirmTech II and second devices among the three firmness classes yielded very low correlation coefficients (Penefel: r 2 = 0.09 to 0.40; Durofel: r 2 = 0.05 to 0.32; DM1600: r 2 = 0.00 to 0.25; FirmTech II: 0.03 to 0.33), suggesting that although all instruments were suitable for evaluating across broad ranges of fruit firmness, they were all similarly unsuitable within a narrow firmness range (e.g., for all soft or all firm fruit). Given the subjectivity of the tactile measurement and the range of variability between the evaluated alternatives, both FirmTech II and Penefel performed better in soft fruit but not as well in moderate or firm fruit. Therefore, among the more economical durometer devices, Penefel could be used by the industry to discriminate soft fruit from moderately firm or firm fruit. The results highlight the relevance of studying the predictive capacity of a particular instrument and to understand the performance of that instrument within a particular range of firmness values.
Hongjian Wei, Wen Yang, Yongqi Wang, Jie Ding, Liangfa Ge, Michael Richardson, Tianzeng Liu, and Juming Zhang
Traffic resistance of turfgrasses is an essential indicator of urban recreational and sports turf quality (TQ). In our study, four turfgrass species were investigated for their wear resistance. A self-made traffic simulator was used to determine the wear resistance of the study turf area in a 2-year field trial (2019–20). The experimental plots were established using a randomized block design with three replicates. The morphological characteristics, soil physical properties, and physiological indices of the grasses were analyzed. Using the acquired quantitative data, we set the turf cover index (TCI), the turf quality index (TQI), and the shoot density index (SDI) as the wear tolerance index, and assessed the correlations among these morphological characteristics, soil physical properties, physiological indices, and wear tolerance. ‘Lanyin III’ zoysiagrass and ‘Tifgreen’ hybrid bermudagrass provided relatively greater wear tolerance, followed by ‘Qingdao’ zoysiagrass and common bermudagrass after 12 weeks of traffic exposure in 2019 and 2020. Traffic changes the soil physical properties and affects the physiological metabolism of turfgrasses. Leaf morphology characteristics and the mechanical strength of these grasses were related significantly to TCI, TQI, and SDI, and most physiological responses and soil properties correlated significantly with TCI and TQI. Our findings of the correlations among physiological responses, soil properties, leaf morphology, and wear tolerance will allow grass breeders to evaluate their breeding procedures more efficiently.
Boitumelo Patience Lekgoathi, Puffy Soundy, and Pholosho Mmateko Kgopa
Water scarcity coupled with an increasing demand for water in agriculture has forced farmers to amend their irrigation practices and water management strategies. The proposed study was aimed at evaluating physiological and growth traits [photosynthesis rate, stomatal conductance (g S), chlorophyll content, leaf area, and fresh weight] under three irrigation levels (50%, 75%, and 100% of field capacity) in five varied textured soils (clay, clay loam, loam, sandy loam, and sandy). Response was evaluated on two baby spinach (Spinacia oleracea L.) cultivars (Dash and Hellios). Regarding physiological parameters, there were no interaction effects of deficit irrigation (DI) × soil texture. Significant increase on growth parameters (chlorophyll content, leaf weight, and leaf area) were observed under the interaction of 75% DI × sandy loam and loam soils on both ‘Dash’ and ‘Hellios’ during Season 1. ‘Hellios’ was able to adapt to deficit level of 75% during both growing seasons (summer and winter) under sandy loam soils. The study indicated that 25% water can be saved under sandy loam and loam soils when cultivating baby spinach during winter conditions.
Yahia A. Othman and Daniel I. Leskovar
Polyethylene mulch is widely used for vegetable production in the United States as a tool to conserve water, control weeds, and produce earlier and cleaner products (i.e., less attached soil). However, the increasing labor costs for mulch removal and disposal after harvest and soil environmental pollution are major concerns. The objective of this study was to assess fruit yield and quality, mulch deterioration, soil microbial activity, and nutrient changes in ‘Stargazer’ watermelon (Citrullus lanatus) grown with degradable plastic mulch. The deterioration rates of degradable mulch were 7%, 37%, 57%, and 92% after 120, 210, 300, and 365 days, respectively, of placing the mulch in the field. However, the extra difference in using degradable mulch was calculated as $58.6/acre (polyethylene $600.9/acre vs. degradable $659.5/acre), including all costs associated with laying and disposing. One year after placing mulch in the field, the nitrate content and total and active fungi numerically increased (P = 0.08) in soils with the degradable mulch compared with polyethylene mulch. However, there were no statistical differences in soil phosphorus, potassium, organic carbon, and total and active bacteria. Extra-large fruit size yield (category >24.0 lb) from the polyethylene mulch treatment was higher than that from degradable mulch, whereas the 18.0- to 24.0-lb category was lower than that with degradable mulch. However, total yield and total soluble solids from both mulches were statistically similar. Considering the complete deterioration (less waste), mulch removal cost (not required), microbial associations (higher fungi abundance and activity), and similar yield and fruit quality of degradable mulch compared with polyethylene, the implementation of degradable mulches in commercial watermelon field practices is promising.