Horticultural Plant Production Research Articles

Research on the Implementation Path of Ideological and Political Education in the “Horticultural Plant Production Technology” Course under the Rural Revitalization Strategy

Research on the Implementation Path of Ideological and Political Education in the “Horticultural Plant Production Technology” Course under the Rural Revitalization Strategy

Environmental Influences on the Drying Rate of Spray-Applied Disinfestants from Horticultural Production Surfaces

Drying rates of disinfestants commonly applied to horticultural plant production surfaces were evaluated under cool to hot weather and under laboratory conditions to characterize the range of drying times and how this relates to contact times specified on product labels. Drying rates of six disinfestants (isopropyl alcohol [IPA], two quaternary ammonium compounds [QACs], two peroxygen compounds [PXs], and sodium hypochlorite [bleach]) and water were evaluated when applied to six substrate materials (concrete, galvanized metal, polypropylene ground fabric, polyethylene plastic sheet, pressure-treated pine, and twin-wall clear polycarbonate) based on the weather variables of solar radiation, temperature, and relative humidity. Differences were evident at the point of application. Disinfestants with low (IPA, both QACs, and one PX) and high (bleach, one PX, and water) surface tension provided approximately 100 and 60% coverage, respectively, when applied to horizontal, nonporous solid materials. Disinfestants applied to horizontal porous materials (concrete, fabric, and wood) persisted on the surface for a mean of only 9 to 113 s because solutions were actively drawn into the substrates’ internal structure. Disinfestants applied to vertical twin-wall greenhouse material flowed off, while retaining only a maximum beaded wetness coverage of 14%. A Bayesian analysis procedure was used to model drying effects of disinfestants correlated with substrate and weather variables based on posterior marginal and prediction trends. Generally, the fastest drying rate occurred in the first 2.5 min, and approximately 50% of coverage was retained by 5 min. The evaporative process was variable with distinct interactions occurring among the experimental variables. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

Environmental Influences on the Evaporation Rate of Horticultural Disinfestants

The evaporation rate of disinfestants when sprayed on production surfaces is expected to vary under different weather conditions, but it is unknown how that affects efficacy. This study was an initial investigation into how the evaporation rates of water and six commercial disinfestants vary under eight weather condition categories. Additionally, an empirical model was developed on the evaporation rate of water in response to air temperature, relative humidity, solar radiation, vapor pressure deficit, and wind speed under the same eight weather condition categories. Isopropyl alcohol lost more weight due to evaporation over 4 h ( P < 0.0001) than all other disinfestant solutions, and no differences ( P = 0.05) existed between the other five disinfestant solutions and water. Isopropyl alcohol had a mean percentage weight loss of 71% under hot and sunny conditions, 43% under cool and cloudy conditions, and 6% under indoor laboratory conditions. Water, hypochlorite, quaternary ammonium, and peroxy disinfestant solutions evaporated at a similar rate over 4 h, with an approximate mean percentage weight loss of 17% under hot and sunny conditions, 6% under cool and cloudy conditions, and 1% under indoor laboratory conditions. The regression model that best explained the influence of weather on evaporation included the variables solar radiation, temperature, and wind speed ( P < 0.0001, R2 = 0.5603). This information will be used further to model the evaporative rate of disinfestants under the same range of weather conditions when applied to multiple types of substrate materials that represent common horticultural plant production surfaces. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

Addition Pinus massoniana fallen wood improved the growth of Plagiomnium acutum in a substrate cultivation

Soilless culture has been widely used in horticultural plant production, but little research has been done on bryophyte. In this study, we selected a cultivation substrate mixed and proportioned with garden soil, granular soil, grass charcoal soil, general-purpose nutrient soil, and decomposed grade II, III, and IV fallen wood of Pinus massoniana as the raw materials of soilless substrate to investigate its effects on the growth and physiology of Plagiomnium acutum. The results showed that the total porosity, water-holding porosity, and water-holding capacity of the mixed substrate containing fallen wood of P. massoniana were significantly higher than those of other cultivated substrates. The average cover of the P. acutum was significantly and positively correlated with the substrate’s total porosity and water-holding porosity. Chlorophyll content was highly significantly and positively correlated with the water holding capacity and total nitrogen content of the substrate. Among them, VIII decomposition grade Pinus massoniana fallen log:Vgrass charcoal soil = 1:1 (SW8) substrate had the highest overall evaluation index and the best overall growth condition of P. acutum. In summary, VIII decomposition grade Pinus massoniana fallen log:Vgrass charcoal soil = 1:1 (SW8) substrate can be the best substrate for cultivation of P. acutum. The addition of P. massoniana fallen wood to the soil substrate increased the total porosity, water-holding porosity, and water-holding capacity of the substrate, which was conducive to the growth of P. acutum and the increase of chlorophyll content.

Effects of biochar as a peat-based substrate component on morphological, photosynthetic and biochemical characteristics of Rhododendron delavayi Franch.

Biochar could be a promising peat substitute for horticultural plant production. We evaluated the feasibility of rice husk biochar (RHB) and wood chip biochar (WCB) as a peat-based substrate component for the cultivation of Rhododendron delavayi Franch., that is an ornamental dwarf tree species. A pot experiment was conducted to test the effects of RHB and WCB treatments at five application rates ( 0, 10, 20, 30, and 40% by volume) on morphological, photosynthetic and biochemical characteristics of R. delavayi. The substrate properties, plant growth, root traits, photosynthetic and biochemical parameters were analyzed. The addition of 20% WCB or 30-40% RHB enhanced the growth and photosynthetic activity of R. delavayi seedling, including increased plant height, numbers of leaves, leaf area, root surface area and root tip numbers, as well as improved total chlorophylls content and net photosynthetic rate. The addition of 40% RHB significantly increased the contents of carotenoids, polyphenols and anthocyans, indicating an enhanced antioxidant activity of R. delavayi seedlings. The mixed substrates (20% WCB, 30% RHB and 40% RHB) all have balanced aeration porosity and water holding porosity, suitable pH and electrical conductivity, and increased plant nutrient supply (especially K, Fe and Mn). However, the 40% WCB substrate depressed seedlings growth and reduced total chlorophylls content and net photosynthetic rate. The negative effects were linked to its low water holding porosity, high alkalinity and salinity, as well as high content of phytotoxic compounds, such as polycyclic aromatic hydrocarbons and volatile matter. In conclusion, a peat-based substrate containing 20% WCB or 30–40% RHB is a more favorable growth media for obtaining high-quality R. delavayi seedlings, while achieving sustainable horticulture production.

Automated workflow analysis in vegetable grafting using an Ultra-Wide Band based real-time indoor location tracking system

• Automatically extracting information for workflow analysis from raw sensory data. • Developing a framework for workflow analysis using Ultra-Wide Band technology. • Identifying worker and task associations based on the location data. • Automatically calculating flow time, processing time, and waiting time from Gantt charts. • Achieving 90.54% accuracy in validating the proposed algorithms against the video data. Traditional workflow analysis requires intensive manual processes to extract meaningful information from raw sensory data. A novel framework for workflow analysis is developed based on a real-time indoor location tracking system utilizing Ultra-Wide Band technology. The proposed framework is applied to identify worker and task associations in a labor-intensive horticultural plant production process for grafted vegetable seedlings, based on location data. It involves binary segmentation of different distance measures calculated from location data to detect the plant tray’s movements and worker association in the vegetable grafting operation. An iterative overlap time removal algorithm is then implemented to ensure that no worker is assigned to overlapping processes, and no task is processed by multiple workers simultaneously. Key workflow metrices such as flow time, processing time, and waiting times are automatically calculated. Automatically generated Gantt charts and bar plots provide valuable insights into the workflow for management and help them identify improvement opportunities. Validation of results with video data show that the proposed workflow analysis is 90.5% accurate.

Efficacy of Hypochlorite in Disinfesting Nonfungal Plant Pathogens in Agricultural and Horticultural Plant Production: A Meta-Analysis.

Bleach products containing hypochlorite are commonly used as disinfectants to eliminate nonfungal plant pathogens from production surfaces, tools, plant surfaces, irrigation water, and produce dump tanks. Although bleach products are useful, their effectiveness has been reported to vary under specific settings. A meta-analysis was conducted of 86 studies to assess the overall efficacy of hypochlorite against plant pathogenic bacteria, oomycetes, and viruses and to identify factors that explain differences in product efficacy. Hypochlorite resulted in a significant (P < 0.0001) reduction in disease intensity or propagule viability, with a mean Hedges' g standardized difference ([Formula: see text]) of 3.01, indicating that overall, hypochlorite treatments are highly effective. However, heterogeneity in g was significant (P < 0.0001) between studies, wherein 69.8% of the variance observed in g was attributed to true effects. Furthermore, an estimate of between-study variability was moderate (τ2 = 1.46). Random effects (REs) metaregression showed limited effects of moderator variables dosage, contact time, targeted material of treatment, and organism type on product efficacy when all organism types were considered together. Because subgroup [Formula: see text] was significantly higher (P = 0.0070) for oomycetes ([Formula: see text] = 3.30) than for bacteria ([Formula: see text] = 2.19), subsequent metaregressions were performed by organism type. For oomycetes, five RE metaregression models, each containing two moderators and their interaction, resulted in significant (P = 0.05) effects, where models with dosage and time, dosage and genus, time and genus, dosage and target, and time and target accounted for ≤50, 71, 57, 48, and 47%, respectively, of the variance in true effect sizes (R2) associated with [Formula: see text]. For viruses, only the RE metaregression model containing time and target and their interaction resulted in significant (P = 0.0435) effects accounting for 38% of the variance in true effect sizes associated with [Formula: see text]. None of the RE metaregression models for bacteria were significant, although they still accounted for ≤28% of the variance in true effect sizes associated with [Formula: see text]. These results show that although the current recommended rates for dosage and contact time for commercial bleach products are generally expected to result in effective disinfestation, the efficacy against nonfungal plant pathogens is expected to be influenced by the organism type and target being treated with hypochlorite.

Efficacy of Hypochlorite as a Disinfestant Against Fungal Pathogens in Agricultural and Horticultural Plant Production: A Systematic Review and Meta-Analysis.

Hypochlorite is often used as a disinfestant of fungal pathogens in a range of agricultural and horticultural settings. However, reports of its effectiveness are variable across studies and it is unclear what factors could potentially influence the reported estimates of its efficacy. A systematic review and meta-analysis was conducted to assess the efficacy of hypochlorite against fungal pathogens and explore factors that may explain the observed heterogeneity in estimates of efficacy. Standardized mean effect size, Hedges' g, was calculated for each of the 109 selected studies, published from 1972 to 2019, that met the criteria defined for the systematic review. A random-effects model was used to estimate the overall mean effect size ([Formula: see text]) and determine the heterogeneity in g among studies. Hypochlorite resulted in a significant (P < 0.001) reduction in either disease intensity or propagule viability with [Formula: see text]= 2.25, suggesting a large overall effect. However, 95% prediction intervals ranged from -0.18 to 4.68, indicating that hypochlorite could be ineffective against some fungi or when targeting some substrate materials. An estimate of the within-study variability, τ2, was 1.48 and the proportion of heterogeneity in g among studies due to true effects was 71.5%. Inclusion of categorical moderator variables in the random effects model showed that hypochlorite treatments were significantly (P < 0.0062) more effective when used to disinfest spores in an aqueous solution ([Formula: see text]= 4.58) than when used on plastic ([Formula: see text]= 2.13), plant ([Formula: see text]= 2.13), and wood ([Formula: see text]= 0.79). Similarly, hypochlorite treatments were significantly (P < 0.0083) more effective in disinfesting fungal propagules of Thielaviopsis spp. ([Formula: see text]= 2.51) than those of Verticillium spp. ([Formula: see text]= 1.21). A meta-regression indicated that the effect of dose (β = -3.54; P = 0.0398) and contact time (β = -0.05; P = 0.0001) on [Formula: see text] were highly significant. Further, [Formula: see text]was significantly affected by the dose × time interaction (β = -0.017; P = 0.0269). In the meta-regression models, dose and time explained 0 and 16% of the variance in true effects, respectively. In meta-regression models with a continuous variable of dose or time, a categorical variable of target or genus and their interaction term, genus and target explained an additional 7 to 19% of the variance in true effects. These results show that although the current recommended dose and contact time for commercial bleach products are expected to result in effective disinfestation, the target material and genera of the fungal pathogen of interest will likely influence their efficacy.

Overexpression of the Brassica rapa SRS7 gene in pot-type chrysanthemum [Chrysanthemum morifolium Ramat] reduces plant height

Retardation of plant growth is important in horticultural plant production and is generally achieved through the application of various chemical plant growth regulators (PGRs). Chrysanthemum plants grown in pots (pot-mums), are typically treated with PGRs to produce a compact form; however, these compounds can be hazardous to the environment and human health. In an effort to develop a method to produce compact chrysanthemum plants without using PGRs, we introduced the BrSRS7 gene from Brassica rapa L. ssp. pekinensis into chrysanthemum with its expression controlled by the promoter of the chrysanthemum actin gene (CmActin). As a first step, we evaluated the regeneration capacities of seven pot-mum cultivars and identified the Peace Copper (PC) cultivar as having the best regeneration efficiency. After transformation of the BrSRS7 gene into PC followed by selection and 5 rounds of vegetative subcultivation, 11 transgenic lines were identified for analysis. Internode lengths were reduced in all lines compared to control plants, but plant heights of some lines were similar to those of control plants. Four transgenic lines were selected for a sixth round of subcultivation and for further study. We determined the relative expression levels of gibberellin- and auxin-related genes in the four transgenic lines. Of the auxin-related genes, ARF2 and YUCCA10 showed higher expression in the transgenic lines than in the control. The expression levels of GA-related genes decreased overall in P-33, which showed the greatest decrease in height. Subjecting the transgenic lines to a dwarfing treatment with the PGR B9 showed that the plants could be reduced to actual marketable size with only a single dwarfing treatment. Our results demonstrate the possibility of using the BrSRS7 gene to produce compact chrysanthemum plants with reduced or no use of PGRs.

Phosphorus restriction influences P efficiency and ornamental quality of poinsettia and chrysanthemum

Better synchronization of plant-available phosphorus (P) with crop P requirement is required to reduce P losses to the environment and to improve resource-efficiency of the exploitation of non-renewable phosphate rock. In horticultural plant production, a restricted availability of P may limit stem length and improve compactness, which are desirable characters for many ornamental plants. In the present study, we investigated the effect of reduced availability of P on plant quality, biomass production and phosphorus efficiency of poinsettia (Euphorbia pulcherrima cv. ‘Mira Red’) and chrysanthemum (Chrysanthemum × morifolium cv. ‘Breeze Cassis’). Five P concentrations (6, 12, 18, 24 or 48 mg L−1) were applied as starter P in the peat-based potting substrate as well as in the nutrient solution given during the experiment. Stem length of both plant species was strongly restricted at 6 mg P L−1 but was not significantly affected by higher P levels. For poinsettia, the optimum bract diameter was obtained at 18 mg P L−1. For maximum shoot dry biomass, branching and plant diameter, however, 24 mg L−1 was needed. Optimal plant diameter and shoot biomass of chrysanthemum was obtained at 18 mg P L−1 while 24 mg L−1 was required for maximum flower number. Increasing the P supply to 48 mg L-1 did not improve shoot dry matter, branching or flowering of either species, but induced luxury uptake of P. Total shoot P uptake increased linearly over the P fertilizer range tested. For optimal plant biomass combined with optimal ornamental quality, shoot P concentrations at 90 DAP was in the range of 0.30-0.35 % for poinsettia and 0.25-0.30 % for chrysanthemum. Chrysanthemum showed a higher phosphorus efficiency than poinsettia at low P levels, mainly related to a higher internal P utilization efficiency. The P acquisition efficiency was in the range of 55–60 % for both species, and was not significantly affected by the total amount of P applied. In conclusion, with the P fertilization strategy used, P restriction could not be used for plant height restriction of poinsettia “Mira Red” or chrysanthemum “Breeze Cassis” without negative effects on plant quality. However, P fertilization could be markedly reduced without negative effects on plant growth and development, improving phosphorus efficiency and recovery.

Impact of dark septate endophytes on tomato growth and nutrient uptake

ABSTRACT Background Dark septate endophytes (DSEs) represent a form-group of ascomycetous fungi that inhabit the roots of a wide range of plant species, but our knowledge on their interaction with the host plants is still limited. Aims This study was conducted to examine the effect of DSEs on the nutrition and growth of tomato (Solanum lycopersicum) in order to assess their potential application in horticultural plant production. Methods The capacity of two model DSE species, Periconia macrospinosa and Cadophora sp. to mobilise different forms of N and P (organic and inorganic) was analysed, and an in vitro bio assay with tomato plantlets was applied to screen the compatibility of these fungi with the plant. Pot-culture experiments with and without compartments were conducted to study the effects of these DSEs on the growth and nutrient uptake of tomato plants grown with organic and inorganic N and P sources. Results Periconia macrospinosa, but not Cadophora sp., increased the root and shoot biomass of tomato plants when organic nutrient resources were present, and both DSEs promoted shoot growth when cultivated with inorganic fertilisers. Analysis of N and P concentrations indicated that the growth response of tomato with inorganic fertilisation was not based on DSE-improved plant nutrition. However, P. macrospinosa improved N uptake from organic sources. Conclusion The positive effects of DSEs seem to be due to nutrient mobilisation rather than to hyphal transport to the plant.

Identification of fungi originated from soil polluted by Dichloro Diphenyl Trichloroethane (DDT)

Since the last twenty years Merdeka Village in Merdeka Subdistrict, Tanah Karo District, Indonesia had been the centre of horticultural plant production for the North Sumatra Province. Insecticide commonly used by farmers in this area was of organochloric active ingredient, namely Dichloro Diphenyl Trichloroethane (DDT).The DDT was an insecticide that was degraded very difficultly by the soil, was toxic and persistent in the soil for decades. This insecticide caused changes in soil microbiology, including fungi. Soil sampling using a soil drill at a depth of 0-20 cm with a diagonal sampling method of 45 sample points. Subsequently the soil samples were taken to the Pesticide Laboratory at the North Sumatra Plantation Seed Germination Center for extraction using the Quechers Tube Method using three material variables, namely sodium acetate (Na-acetate), primary secondary amine (PSA) and octadecylsilane (C18) with Gas Chromatography-Mass Spectrometry (GC-MS). The results showed that DDT derivatives were found in B o’p’DDD soil at the amount of 1.6 μgKg-1, and at C o’p’DDD soil at 2.2 μgKg-1. The DDT residues in both locations B and C were classified as dangerous because they exceeded the DDT standard of 0.7 μgKg-1 dry soil which refered to the Canadian Environmental Quality Guidelines (CCME). Soil samples containing five grams of DDT residue were then isolated and fungi growing on the soil were identified. Identification of fungi showed that Mucor sp, Fusarium sp and Trichophyton sp were found.

Can narrow-bandwidth light from UV-A to green alter secondary plant metabolism and increase Brassica plant defenses against aphids?

Light of different wavelengths is essential for plant growth and development. Short-wavelength radiation such as UV can shift the composition of flavonoids, glucosinolates, and other plant metabolites responsible for enhanced defense against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. The increasing use of light-emitting diodes (LEDs) in horticultural plant production systems in protected environments enables the creation of tailor-made light scenarios for improved plant cultivation and induced defense against herbivorous insects. In this study, broccoli (Brassica oleracea var. italica) plants were grown in a climate chamber under broad spectra photosynthetic active radiation (PAR) and were additionally treated with the following narrow-bandwidth light generated with LEDs: UV-A (365 nm), violet (420 nm), blue (470 nm), or green (515 nm). We determined the influence of narrow-bandwidth light on broccoli plant growth, secondary plant metabolism (flavonol glycosides and glucosinolates), and plant-mediated light effects on the performance and behavior of the specialized cabbage aphid Brevicoryne brassicae. Green light increased plant height more than UV-A, violet, or blue LED treatments. Among flavonol glycosides, specific quercetin and kaempferol glycosides were increased under violet light. The concentration of 3-indolylmethyl glucosinolate in plants was increased by UV-A treatment. B. brassicae performance was not influenced by the different light qualities, but in host-choice tests, B. brassicae preferred previously blue-illuminated plants (but not UV-A-, violet-, or green-illuminated plants) over control plants.

Blue Wavelengths from LED Lighting Increase Nutritionally Important Metabolites in Specialty Crops

Light is one of the most important environmental stimuli impacting plant growth and development. Plants have evolved specialized pigment-protein complexes, commonly referred to as photoreceptors, to capture light energy to drive photosynthetic processes, as well as to respond to changes in light quality and quantity. Blue light can act as a powerful environmental signal regulating phototropisms, suppression of stem elongation, chloroplast movements, stomatal regulation, and cell membrane transport activity. An emerging application of light-emitting diode (LED) technology is for horticultural plant production in controlled environments. Work by our research group is measuring important plant responses to different wavelengths of light from LEDs. We have demonstrated positive impacts of blue wavelengths on primary and secondary metabolism in microgreen and baby leafy green brassica crops. Results show significant increases in shoot tissue pigments, glucosinolates, and essential mineral elements following exposure to higher percentages of blue wavelengths from LED lighting. The perception of energy-rich blue light by specialized plant photoreceptors appears to trigger a cascade of metabolic responses, which is supported by current research showing stimulation of primary and secondary metabolite biosynthesis following exposure to blue wavelengths. Management of the light environment may be a viable means to improve concentrations of nutritionally important primary and secondary metabolites in specialty vegetable crops.

Progress Toward Increasing Intake of Dietary Nutrients from Vegetables and Fruits: The Case for a Greater Role for the Horticultural Sciences

Diet is implicated globally in the cause and severity of many diseases, including cancer, heart disease, and diabetes, and a large body of medical evidence indicates that consumption of healthier foods can alleviate both the incidence and severity of not only these diseases, but also obesity, which is a causal factor for many chronic diseases. The 2010 Dietary Guidelines for Americans indicated that several nutrients are underconsumed in the United States, including folate, magnesium, potassium, dietary fiber, and vitamins A, C, and K. Vegetables and fruits are major sources of several of these micronutrients and minerals as well as many other phytonutrients. Despite these health benefits, vegetable and fruit intake by U.S. consumers is significantly lower than recommended by dietary guidelines (less than 40% of recommended intake) and has not risen in the past decade. Collaborations between horticultural plant breeders, production and postharvest scientists with food scientists, nutritionists, medical scientists, marketing specialists, and social scientists are needed to develop plans and take action to stimulate increased vegetable and fruit intake. Increased intake may have a positive impact not only on the health of consumers, but would also increase the economic value of horticultural commodities and raise the profile of horticultural sciences. Horticultural approaches to address this important challenge, and opportunity, must be developed.

Manganese in substrate clays—harmful for plants?

AbstractMixtures of peat and substrate clays are commonly used as growth media for horticultural plant production. A quality protocol for substrate clays defines a threshold value of active manganese (Mnact = sum of exchangeable and easily reducible Mn) in substrate clays of &lt; 500 mg kg–1 to prevent toxic reactions of plants. This threshold value was tested in experiments with peat‐clay blends under various growth conditions, and nutrient solution experiments were additionally conducted to investigate the effects of silicic acid and dissolved organic matter on the occurrence of Mn toxicity. Common bean (Phaseolus vulgaris L.) and hydrangea (Hydrangea macrophylla) plants were cultivated in different peat‐clay substrates and in peat under different moisture and pH levels. The clays varied in their Mnact content from 4–2354 mg kg–1. The results of the substrate experiments reveal that a threshold value for Mn in substrate clays is not justified, as plants grown in all peat‐clay substrates did not develop any Mn toxicity even at high substrate moisture or low pH conditions which are known to increase the Mn availability. The extraction of active Mn did not well reflect the Mn concentrations in plant dry matter and substrate solution. As plants tolerated high Mn concentrations in the substrate solution compared to the nutrient solution without toxicity symptoms, the influence of silicic acid and dissolved organic matter (DOM) on Mn toxicity was characterized in a nutrient‐solution experiment. Manganese toxicity was clearly diminished by silicic acid application, but not by DOM. The former effect probably explains the tolerance of bean plants in peat substrates where high silicon concentrations in the substrate solution were observed. Peat‐clay blends even provided up to five times more silicon to plants than pure peat.

The Future Potential of Horticultural Plant Discovery, Improvement, and Production in Nepal

The country of Nepal is geographically variable and thus has significant diversity in its native flora. Because of physical and social barriers that still exist, many indigenous plant materials have yet to be adequately screened for their uses not only within Nepal, but outside its borders. Maximum production of horticultural crops in Nepal will require improved water distribution, adequate pest control, and consideration of social/demographic issues.

Growth and physiological responses of Chinese cabbage and radish to long-term exposure to elevated carbon dioxide and temperature

Future forecasts for climate change predict the global mean surface air temperature rise by 1–4°C and double current atmospheric CO2 level before the end of 21 century. Increased atmospheric temperature and CO2 concentration are particularly important concerns for agricultural, horticultural and native plant production. In this study, effects of long-term exposure to elevated temperature and carbon dioxide (CO2) on the growth and physiological responses of 3 cultivars of Chinese radish (Raphanus sativus L.) and 3 cultivars of Chinese cabbage (Brassica campestris L.) were examined. In result, the radishes exposed to elevated CO2 for 90 days after sowing (DAS) resulted in little or no change in the root dry weights and the rate of photosynthesis compared with those grown in ambient levels of CO2. In contrast, long-term exposure to elevated CO2 in cabbage had variable effects on the leaf dry weight. As a result of acclimating to the elevated temperature, the radish ‘Chunha’ had a higher rate of photosynthesis, stomatal conductance and internal CO2 concentration than in the control condition. Furthermore, the long-term exposure to a combination condition of elevated temperature and CO2 increased root dry weights of the radishes ‘Cheongdae’ and ‘Chunha’ more than elevated temperature alone. The combination of elevated CO2 and temperature stimulated the growth of roots more than that of shoots in the radish ‘Chunha’, and thus may have led a higher rate of nutrient uptake than other radish cultivars. In contrast, when the cabbage ‘Chun-gwang’ was exposed to a combination of elevated temperature and CO2 for 90 DAS, the leaf dry weight decreased about 3-fold more than that only exposed to elevated CO2 with drastic decreases in stomatal conductance, internal CO2 and photosynthesis rate. When the cabbage ‘Samjin’ was exposed to either elevated temperature alone or both elevated temperature and CO2 for 80 DAS, the decrease in the leaf dry weight was less than that of the other cabbage cultivars. Results indicated that the radish ‘Chunha’ and the cabbage ‘Samjin’ tolerated either elevated temperature alone or combination condition of elevated temperature and CO2 more than other cultivars.

Production of compact plants by overexpression of AtSHI in the ornamental Kalanchoë

Growth retardation is an important breeding aim and an essential part of horticultural plant production. Here, the potential of transferring the Arabidopsis short internode (shi) mutant phenotype was explored by expressing the AtSHI gene in the popular ornamental plant Kalanchoë. A 35S-AtSHI construct was produced and transferred into eight genetically different cultivars of Kalanchoë by Agrobacterium tumefaciens. The resulting transgenic plants showed dwarfing phenotypes like reduced plant height and diameter, and also more compact inflorescences, as a result of increased vegetative height. The shi phenotype was stable over more than five vegetative subcultivations. Compared with Arabidopsis, the ectopic expression of AtSHI in Kalanchoë showed several differences. None of the Kalanchoë SHI-lines exhibited alterations in leaf colour or morphology, and most lines were not delayed in flowering. Moreover, continuous treatment of lines delayed in flowering with low concentrations of gibberellins completely restored the time of flowering. These features are very important as a delay in flowering would increase plant production costs significantly. The effect of expression controlled by the native Arabidopsis SHI promoter was also investigated in transgenic Kalanchoë and resulted in plants with a longer flowering period. Two AtSHI like genes were identified in Kalanchoë indicating a widespread presence of this transcription factor. These findings are important because they suggest that transformation with the AtSHI gene could be applied to several species as a tool for growth retardation, and that this approach could substitute the use of conventional chemical growth regulation in plant production.

Program Pengembangan Agrobisnis Holtikultura dengan Metode Policy Analysis Matrix

In general, the purpose of this study is to find out the level of success of the development program of horticultural based agribusiness administered by the Directorate General of Horticultural Plant Production Development. This study uses macro indicators including production development and productivity of horticultural commodity, development of national added value, and development of contributions to the national food self sufficiency; while the micro indicators include profitability level of the horticultural agribusiness, competitive level, and the issues and problems that must be faced while the PPAH program is in progress.