Dormancy breaking of ‘Kampai’ peach trees with alternative products in subtropical regions

Peach trees initiate flowering and then dense budding when the temperatures in winter are steadily low. When temperatures during the winter are high or when the chilling accumulation needs of the cultivar are not met, it is necessary to apply chemicals that stimulate flowering and budding in a uniform manner. This study aimed to evaluate alternative products for breaking the dormancy of ‘Kampai’ peach trees in a subtropical region. The experiment was conducted with ‘Kampai’ peach trees in the 2018, 2019 and 2020 production with the following treatments: (1) negative control composed only of water (control); (2) positive control composed of hydrogen cyanamide at a dose of 1.5% (commercial product Dormex®) plus 4.5% mineral oil; (3) Erger G® organomineral fertilizer supplemented with calcium nitrate at a dose of 3%; (4) potassium nitrate at a dose of 5%; and (5) copper sulphate at a dose of 0.3%. We evaluated affected budding capacity, flowering, the production cycle, peach production, the quality of peach trees and the enzymatic activities of catalase and guaiacol peroxidase. Hydrogen cyanamide and the organomineral fertilizer Erger G® promoted earlier flowering and an earlier production cycle. On the other hand, hydrogen cyanamide and copper sulphate stimulated flower opening and peach production. The chemicals used decreased catalase activity (24 h after application) and increased guaiacol peroxidase activity (6 h after application). The application of copper sulphate may be an option to break the dormancy of peach trees in the subtropics.

PRODUCTIVITY AND QUALITY EVALUATION OF TARRAGON AND THYME GROWN UNDER ARTIFICIAL LIGHT

The research aimed at evaluation of productivity and quality of tarragon and thyme medicinal material was carried out on hydroponic installations during 2019-2020. The objects under study were Monarkh and Gudvin tarragon varieties as well as Medok and Zmeyka thyme varieties. The plants were grown in mineral cotton substratum. Fertikea Hydro complex fertiliser with microelements and calcium nitrate were used. The growing conditions: ambient temperature +22…+25℃, solution temperature +20℃, ambient humidity 55…65%. Experiment regimens: growing under white LEDs (luminous flux 8000 lm, color temperature 4000 K, PPF 165 mkmol/s/m2) and color LEDs (combination of red, blue and white LEDs (32:16:32), luminous flux 6573 lm, PPF 143 mkmol/s/m2), for 16-hour light regimen. We found that thyme grown on a vertical hydroponic system increase its biomass 2.0…3.5 times compared to the conventional growing. The highest productivity of Zmeyka thyme variety is reached under white light, while for both the tarragon varieties and Medok thyme variety it is reached under coloured LEDs. Chlorophyll-a content in green biomass is a little higher under coloured LEDs for Zmeyka thyme variety and Gudvin tarragon variety, while the reverse trend is observed for Monarkh tarragon variety. All the varieties show higher chlorophyll-b content under coloured LEDs. Combined chlorophyll-a and chlorophyll-b content increases under coloured LEDs for the thyme varieties and Gudvin tarragon variety. Monarkh tarragon variety shows the highest combined chlorophyll content under white LEDs. Carotenoid concentration in Medok thyme variety and Monarkh tarragon variety is higher under white LEDs and it is higher under color LEDs for the rest of the varieties. Flavonoids in the studied varieties accumulate statistically better (1.5…3.0 times) under white LEDs

Preplant Fertilization Increases Substrate Microbial Respiration But Does Not Affect Southern Highbush Blueberry Establishment in a Coconut Coir-based Substrate

Coconut coir is widely used as a substrate component for southern highbush blueberry [(SHB) Vaccinium corymbosum L. interspecific hybrids] cultivation in containers. Coconut coir-based substrates can exhibit high potassium (K), sodium (Na), and chlorine (Cl) concentrations. Sodium in the substrate is particularly problematic because it can cause salinity stress and nutritional imbalances in young blueberry plants. Thus, Na removal is important to ensure transplant success. We hypothesized that preplant fertilization with large volumes of nutrient solution can reduce substrate salinity, replace Na with nutritional cations, and enhance blueberry establishment. We tested this hypothesis in a greenhouse experiment with ‘Snowchaser’ SHB grown in rhizoboxes filled with a 7:3 mix of coconut coir and perlite. Four different treatments were delivered every 24 hours starting 72 hours before transplant. Treatments included 1.75 g⋅L–1 calcium nitrate (CN), 2.38 g⋅L–1 monoammonium phosphate (MAP), deionized water, and well water. One rooted cutting was transplanted to each rhizobox. Rhizoboxes were fertigated during the 7-week cultivation period. We found that preplant fertilization increased nitrogen (N), phosphorus (P), and calcium (Ca) concentrations in the substrate without replacing Na. Thus, preplant fertilization increased substrate salinity. Preplant fertilization also promoted microbial respiration in the substrate at the start of the experiment. Treatments did not affect SHB root architecture, leaf area index, leaf greenness, or biomass accumulation, likely because nutrients delivered by the fertigation solution provided the plants with homogeneous optimal conditions. These findings suggest that preplant fertilization with large volumes of nutrient solution does not enhance blueberry establishment in coconut coir-based substrates.

Effect of Remediation Reagents on Bacterial Composition and Ecological Function in Black-Odorous Water Sediments

Black-odorous urban water bodies and sediments pose a serious environmental problem. Herein, we conducted microcosm batch experiments to investigate the effect of remediation reagents (magnesium hydroxide and calcium nitrate) on native bacterial communities and their ecological functions in the black-odorous sediment of urban water. The dominant phyla (Proteobacteria, Actinobacteria, Chloroflexi, and Planctomycetes) and classes (Alpha-, Beta-, and Gamma-proteobacteria, Actinobacteria, Anaerolineae, and Planctomycetia) were determined under calcium nitrate and magnesium hydroxide treatments. Functional groups related to aerobic metabolism, including aerobic chemoheterotrophy, dark sulfide oxidation, and correlated dominant genera (Thiobacillus, Lysobacter, Gp16, and Gaiella) became more abundant under calcium nitrate treatment, whereas functional genes potentially involved in dissimilatory sulfate reduction became less abundant. The relative abundance of chloroplasts, fermentation, and correlated genera (Desulfomonile and unclassified Cyanobacteria) decreased under magnesium hydroxide treatment. These results indicated that calcium nitrate addition improved hypoxia-related reducing conditions in the sediment and promoted aerobic chemoheterotrophy.

Effect of different levels and sources of calcium on post harvest physiology of hybrid tomatoes (Solanum lycopersicum)

Due to high respiration and ethylene production, tomato (Solanum lycopersicum) is highly perishable horticulture produce that deteriorates faster during the post-harvest storage period. Calcium nutrition is important to overcome these losses as it helps in retarding ripening process during storage and improve the post-harvest quality tomatoes. Hence a field experiment was conducted with different calcium sources and levels viz., Calcium sulphate, Calcium Nitrate, Calcium silicate, Poultry manure and Pressmud applied at 0, 20, 40, 60 and 80 kg Ca ha-1. A storage study was conducted in a factorial completely randomized block design (FCRD) to ensure the effective role of calcium in post-harvest quality of hybrid tomato. Tomatoes were analyzed for pH of fruit juice, firmness, titratable acidity, total soluble solids, moisture content and physiological loss at five days intervals upto 15 days. The results revealed thatCalcium sources and levels had highly significant impacts on the quality of tomato fruits. The tomatoes harvested from the plot applied with poultry manure at 80 kg Ca ha-1 retained the highest fruit firmness(3.76 N m-1), moisture content (88.2%) and the lowest weight loss (8.82%) in fruit, highertitratable acidity (0.41%), lesser pH (3.61)andtotal soluble solids (4.23 ˚Brix). Hence the application of poultry manure at 80 kg Ca ha-1was beneficial in improving the quality and extending the storage life of hybrid tomatoes.

Improving the Performance of Solar Heat Collector Using Molten Salts

An individual solar collector and two partly freight cylinders filled with molten salts embedded storage tank were connected to each other and forced circulated water by electric pump to improve the thermal performance of residential solar hot water tank. Multi flow rates of 25, 50 and 70 l/h. used to achieve an appropriate flow rate of circulating water. The calcium nitrate tetra hydrate Ca(NO3)2-4H2O and magnesium nitrate hex hydrate Mg(NO3)2-6H2O were mixed to form cheap binary molten salts base on different weight ratios. These molten salts combined could be used as both sensible heat materials and latent heat storage materials, besides they can directly use as heat transfer fluid due to freezing temperature. Six samples of different mixing ratio of molten salts had tested to assess the thermal analysis of each sample. The result indicated that the mixture 60%Ca(NO3)2+40%Mg(NO3)2 had the best performance for thermal storage tank with melting point of 38°C and the thermal value is 8.7 mW, and thermal stability of molten salts were noticed by DSC 60 SHIMADZSU devise.

Bentonite Clay Mixed With Different N Sources Have Variable Effect on Nitrate Leaching From Sandy Soil

Nitrate (NO3) leaching from soils results in lower soil fertility, reduced crop productivity and groundwater pollution. The present study determined NO3 leaching from bentonite [0, 2 and 4% (m/m)] treated sandy soil, under three N sources (calcium nitrate [Ca(NO3)2], ammonium chloride [NH4Cl], urea [CO(NH2)2] @ 300 kg N ha-1) with a leaching fraction of 0.3-0.4. Bentonite markedly reduced NO3 release in leachate, while 4% bentonite retained higher NO3 in soil. The NO3 leaching varied with N sources as Ca(NO3)2>NH4Cl>(CO(NH2)2. This study indicated that soil amendment with bentonite could efficiently mitigate NO3 leaching from soil and hence prevent N fertilizer losses and groundwater pollution.

Maternal Dietary Nitrate Supplementation Lowers Incidence of Stillbirth in Hyper Prolific Sows under Commercial Circumstances

The objective of the current experiment was to investigate whether or not maternal dietary nitrate supplementation, a nitric oxide (NO) precursor, could reduce piglet losses under commercial circumstances. In the current experiment, 120 hyper prolific gilts and sows (Landrace x Yorkshire: Danbred) on a commercial farm in Denmark received either a control lactation diet or a lactation diet containing 0.1% of calcium nitrate (containing 63.1% of nitrate) from approximately 5 days pre-farrowing until day 4 of lactation. The number of piglets born total, alive, and stillborn, as well as birth weights, weights after cross-fostering (approximately 1 day of age), 24 h after cross-fostering, day 3 of age, and at weaning was recorded. Placentas of sows were collected after expulsion and scored on redness. No effect of nitrate supplementation was found on piglet weight, piglet growth, placental redness score, and pre-weaning mortality during lactation. Maternal dietary nitrate supplementation decreased stillbirth percentage with 2.5% (9.9 vs. 7.4%; p = 0.05). It can be concluded that maternal dietary nitrate supplementation shows the potential to decrease the incidence of stillbirth in hyper prolific sows.