Search Results
To evaluate the performance of four newly developed high-intensity-discharge lamp types on plant growth and production, tomato (Lycopersicon esculentum cv. Tradiro F1) plants were grown indoors under 100% artificial lighting for 17 weeks. The four lamp types were: high-pressure sodium high output [HPS(HO)], high-pressure sodium standard [HPS(STD)], metal halide warm deluxe [MH(WDX)] and metal halide cool deluxe [MH(CDX)]. All the lamps tested were 1000 W. HPS(HO) had the highest electrical energy use efficiency (EUE) (0.98 μmol·m–2·s–1·W–1 at 40 cm directly under the lamp); HPS(STD), MH(WDX) and MH(CDX) had 93%, 72% and 61% of the EUE of the HPS(HO), respectively. The photosynthetically active radiation (PAR) outputs of different lamp types had the following order: HPS(HO) > HPS(STD) > MH(WDX) > MH(CDX). The percentage red of PAR of the four tested lamp types had the same order as above, but the percentage blue of PAR of these lamp types had exactly the opposite order. As a result, plants growing under the two HPS lamp types were taller and flowered and fruited earlier than plants under the two MH lamp types. Chlorophyll content index was generally greater in leaves under MH lamps than in leaves under HPS lamps. We recommend that the HPS lamp be used for flowering and fruiting crops and the MH lamp would be better used for foliar and compact crops.
Twenty-four representative melon varieties and six parental cultivars were examined in this study. Among 159 pairs of simple sequence repeat (SSR) primers, 18 SSR core primers with rich polymorphic information, a large number of genotypes, and the ability to distinguish different melon varieties were selected. A total of 113 genotypes were detected among the 30 experimental materials, with an average of 6.28 genotypes for each pair of primers. The polymorphic information content was on average 0.6807, ranging from 0.5618 to 0.7885. Specific bands of the primers for the 30 experimental materials were analyzed, and by combining different primer loci, all 30 varieties were identified. Unique barcodes for molecular identity cards for the 30 experimental materials were established using the fingerprints formed with this SSR marker system. Each variety has a unique identity card that can be applied for the registration of the newly bred varieties, the protection of breeders’ rights, and the authenticity of breeds after promulgation of the new Seed Law of the People’s Republic of China.
Zelkova sinica Schneid. is a popular landscape plant in China because of its wide adaptation, strong disease resistance, large crown, and beautiful fall color. Immature embryos from Z. sinica seeds were cultured on woody plant medium (WPM) supplemented with 4.5 μM 6-Benzylaminopurine (BA) and 5.4 μM α-naphthaleneacetic acid (NAA) to induce callus, and 60% of immature embryos formed callus. The cream-white, friable, nodular callus with proembryogenic structures was then cultured on WPM containing 5.4 μM NAA in combination with 9.0 or 11.2 μM BA to regenerate shoots; approximately five shoots per explant were induced on 70% callus. Shoots were rooted on WPM containing 0.5 μM indole-3-butyric acid (IBA), on which 62.3% shoots developed roots with an average of 4.2 roots per shoot at 4 weeks. The regenerated plantlets were acclimatized and transplanted into the field. This protocol could be used for mass production for field plantation, genetic improvement, and germplasm exchange of Z. sinica.
Recycled irrigation water is one of the major sources of inoculum and may spread plant pathogens throughout the nursery or greenhouse operation. Chlorination is the most economical method of disinfecting water and has been adopted by some North American commercial growers. However, chlorine has not been assessed as a disinfectant for the common plant pathogens Phytophthora infestans, Phytophthora cactorum, Pythium aphanidermatum, Fusarium oxysporum, and Rhizoctonia solani. These pathogens were exposed to five different initially free chlorine solution concentrations ranging from 0.3 to 14 mg·L−1 in combination with five contact times of 0.5, 1.5, 3, 6, and 10 min to determine the free chlorine threshold and critical contact time required to kill each pathogen. Results indicated that the free chlorine threshold and critical contact time for control of P. infestans, P. cactorum, P. aphanidermatum, F. oxysporum, and R. solani were 1, 0.3, 2, 14, and 12 mg·L−1 for 3, 6, 3, 6, and 10 min, respectively.
The phytotoxic threshold of five woody perennial nursery crops to applications of aqueous ozone was investigated to determine if aqueous ozone could be used for remediation of recycled nursery irrigation water and for pathogen control. The perennial nursery crops [Salix integra Thunb. ‘Hakura Nishiki’; Weigela florida Thunb. ‘Alexandra’; Spiraea japonica L.f. ‘Goldmound’; Hydrangea paniculata Seib. ‘Grandiflora’; Physocarpus opulifolius L. Maxim. ‘Summer Wine’] were evaluated for aqueous ozone phytotoxicity after 6 weeks of overhead spray irrigation in which five aqueous ozone treatments (0, 10.4, 31.2, 62.5, 125.0 μmol·L−1) were applied on a daily basis. The concentrations applied represent levels useful for irrigation system maintenance (pathogen and biofilm control) with the highest levels selected to clearly demonstrate phytotoxicity. Aqueous ozone solutions were prepared and injected in-line during irrigation for 7.5 min every day for 6 weeks, after which growth parameters (leaf area, shoot dry weight, root dry weight, height, flower number) were measured and leaf injury was evaluated. High residual aqueous ozone (62.5 μmol·L−1 or greater at emitter discharge; 0.3 m from canopy) in the irrigation water was shown to negatively affect the growth parameters measured; however, low residual ozone concentrations (31.2 μmol·L−1 or less at emitter discharge; 0.3 m from canopy) did not present any measurable risk to plant growth. Furthermore, even at higher dose levels, leaves produced during the treatment period showed reduced damage levels. It is concluded that ozone residuals of 31.2 μmol·L−1 (at emitter discharge) can remain in overhead irrigation water without negatively affecting the crop species examined under the application protocols used. At the ozone concentrations demonstrated to be tolerable by the crop species examined, it is reasonable to surmise that control of pathogens at all points within the irrigation system will be achievable using aqueous ozone as part of an irrigation management strategy. The use of aqueous ozone in this fashion could also aid in dramatically reducing chemical residuals on crops by reducing the input requirements of traditional chemical controls.
Thirteen Chinese cabbage (Brassica rapa) hybrid cultivars and 26 parental inbred lines were used as experimental materials to screen for primers producing hybrid and parental complementary bands and for primers with high polymorphism information contents and low genotype frequencies. A total of 18 pairs of core primers were designed to identify the purity of Chinese cabbage. There was no significant difference in the purity percentage measured between different loci of the same strain. The fingerprint obtained by the amplification of each locus could be used to identify purity to obtain an authentic purity percentage. Curve mapping and significance analyses were conducted using the purity percentage of eight different seed samples and confirmed a sampling seed number of 96. The results of the purity test were verified by comparison with the grow-out test (GOT) using molecular markers. In conclusion, the simple sequence repeat (SSR) detection system could be used for the rapid identification of the purity of the tested Chinese cabbage hybrids.
The rapid expansion of Asian populations in the United States presents significant requirements for Asian vegetables. Flowering chinese cabbage (Brassica rapa L. ssp. chinensis var. utilis Tsen et Lee) is one of the most popular vegetables in China. The main factors restricting the progress in its breeding and genetic studies is the time required in generating desired pure line populations. Doubled haploid (DH) populations of flowering chinese cabbage have not been established because of technical difficulties. An appropriate combined protocol for a fast generation cycling system could advance up to seven generations, allowing the production of pure line seeds within 336–420 days among four cultivars and one hybrid of flowering chinese cabbage. The previous six generation cycles were accelerated using the embryo culture plus soil method which bypassed seed maturation through in vitro culture of immature embryos and promoted plant reproduction under stressed conditions, then the seventh generation cycle was accomplished until mature seeds were harvested using the soil method. During the culture of immature embryos, 12-day-old embryos could germinate and develop successfully on a Murashige and Skoog medium (MS) medium () containing 10% young coconut juice. This combined protocol bypasses the current obstacles in constructing DH populations of flowering chinese cabbage and is a possible alternative for producing pure lines. Its wider adoption could facilitate the breeding and biological studies of other Brassicaceae vegetables.
2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) is one of the most toxic polybrominated diphenyl ethers (PBDEs). The toxic effects of BDE-47 on Chinese cabbage seedlings were analyzed in this study. After a 30-day hydroponic exposure to BDE-47 at different concentrations (25, 50, 75, and 100 µg·L−1), the fresh weight of Chinese cabbage seedlings was significantly decreased, whereas their root:shoot ratio was increased, indicating that BDE-47 inhibited the growth of the plant, especially the overground parts. The water content, chlorophyll content, and protein content of Chinese cabbage leaves also markedly decreased with the increase of the BDE-47 concentration. In addition, BDE-47 weakened the photosynthetic capacity of the leaves, which was supported by the decreased photosynthetic parameters [net photosynthetic rate (P n) and stomatal conductance (g S)]. Although the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in the leaves were enhanced after exposure to BDE-47, the increased malondialdehyde (MDA) content attested to the existence of membrane lipid peroxidation. The increased plasma membrane permeability and the decreased chlorophyll fluorescence parameters [the maximum quantum yield of PSII photochemistry at t = 0 (F v/F m), photosystem II (PSII) reaction centers (RCs) per cross section (CS) (RC/CS), absorption energy flux per CS (ABS/CS), trapped energy flux per CS (TR o/CS), electron transport flux per CS (ET o/CS), performance index on the absorption basis (PI abs), and driving force for photosynthesis (DF)] further proved that the plasma membrane and photosynthetic membrane were damaged by BDE-47. Our study demonstrated the phytotoxicities of BDE-47 to Chinese cabbage, which can provide valuable information for understanding the toxicity of BDE-47 on vegetables.
Ginkgo biloba, a relict plant, has been popularized and planted in most areas of China for its leaves, timber, and fruits. In the present study, the dynamic changes in leaf color, leaf pigment content during the color change period, and photosynthetic characteristics in different growth periods were studied to explore the coloring mechanism and adaptability of five late-deciduous superior Beijing G. biloba cultivars (LD1–LD5). The results showed that the leaf color change of each superior cultivar was relatively stable, and the discoloration period of LD3 and LD5 was later than that of others. From September to November, the chlorophyll a, chlorophyll b, and total chlorophyll content in all superior cultivars showed a downward trend, except in LD3, in which the pigment content was slightly higher in October than in September. Except in LD3 and LD4, the ratio of carotene content to total chlorophyll content in other cultivars slightly decreased in October. In May, the photosynthetic capacity of LD5 was stronger than that of other cultivars. The photosynthetic capacity of LD3 was strong in July and October. Our results imply that LD3 and LD5 are suitable for mixed planting with common G. biloba to increase the overall leaf color viewing period. Ginkgo biloba leaves turn yellow in autumn because of both a decrease in the chlorophyll content after leaf senescence and an increase in the Car content during leaf senescence. Although LD5 presented rapid seedling emergence, LD3 grew faster during the vigorous and late growth stages and is thus suitable for agricultural production.
Commercial citrus species, some of the most important fruit crops worldwide, are sensitive to sub-freezing temperatures. Poncirus trifoliata, a species closely related to commercial citrus and tolerant to –30 °C, has been used in breeding programs or as a rootstock to impart greater freeze tolerance. Gene expression of P. trifoliata and C. unshiu (Satsuma mandarin) were investigated and compared under slow and fast cold-acclimation regimes. The mRNA differential display-polymerase chain reaction (DDRT-PCR) and cDNA-AFLP, coupled with quantitative relative RT-PCR or real-time PCR were used. Many unique gene fragments were isolated and found to be up- or down–regulated as a result of exposure to low temperature. The up-regulated fragments in Poncirus show high similarities to genes involved in osmotic regulation (betaine/proline transporter, water channel protein, and nitrate transporter), oxidative stress (aldoketo reductase, early light induced protein), and protein interaction (tetratricopeptide-repeat protein, F-box protein, and ribosomal protein L15). In C. unshiu the up-regulated genes show high similarities to genes involved in transcription (zinc finger and GTP-binding protein-related), signal transduction (14–3–3 protein and extension-like protein), protein synthesis and amino acid translocation (permease and ribosomal proteins), chromosome folding (chromosome condensation, structural maintenance of chromosomes-like protein), and carbohydrate metabolism (glycosyl transferase). Several genes involved in photosynthesis, defense and cell wall metabolism were down regulated. Characterization of cold responsive genes will be discussed.