Experiments were conducted on 6-month-old chinese ixora (Ixora chinensis Lam.) from February 1999 to April 2000. Floral development was studied with scanning electron microscopy (SEM) to determine the flowering sequences. Morphological characters were used to clarify the stages of flowering processes. The time of organogenesis and flowering arrangement was established through field observations. Floral evocation occurred in early September, floral initiation occurred in the middle of September and floral differentiation began in late September. A distinctly convex apex with bracts around the shoulder indicated the beginning of reproductive development. Subsequently, primary inflorescence axes were observed and differentiated into secondary, tertiary, and quaternary inflorescence axes consecutively in about one and a half months. Once the terminal apex reached the inflorescence bud stage, it would flower without abortion, and this may be assessed as no return. The sepals, petals, stamens, and pistil were well developed thereafter and anthesis was achieved in January through March in the following year. The observation of floral differentiation sequences and investigation of floret arrangement made it certain that chinese ixora had cymose inflorescence (cyme), but not corymb. A quadratic equation was established to predict floret number from the differentiation level (a quantitative description of differentiation stage) of a developed inflorescence.
Hybridization at intraspecific, interspecific, and intergeneric levels is a well-known breeding strategy to create variations with desirable traits for ornamental flowers. A total of 161 crossing combinations were made on three taxonomic levels, including 12 intraspecific crossing combinations within L. chalcedonica and L. ×haageana, 102 interspecific crossing combinations within Lychnis spp., and 47 intergeneric crossing combinations between Lychnis spp. and Silene spp. Intraspecific crosses showed high cross-compatibility, which yielded mature seeds and progeny plants. Most of the interspecific crossings in genus Lychnis produced limited seed set and germination percentages; however, L. cognate, L. ×arkwrightii, and L. ×haageana showed high cross-compatibility and might be more closely related than other species in Lychnis. As a result of cross-incompatibility, crossing combinations between Lychnis spp. and Silene spp. produced few flowers that set seeds. Significant differences occurred in seed set between crossing combinations and their reciprocal crosses for interspecific and intergeneric crosses. For these hybrids with immature seeds, embryo rescue techniques with immature seed culture would be the only way to produce seedlings.
Seeds of most Pedicularis species do not germinate easily and uniformly, which hinders the process of seeking solutions for successful cultivation of these taxa. In an attempt to determine optimal conditions and effective methods for uniform, rapid, and high-percent germination, the effects of light, scarification, and gibberellic acid (GA3) were tested on seed germination of eight Pedicularis species from nine sites in the northwestern Yunnan Province of China. There were some differences in germination characteristics among the tested species. Seed germination of some species was promoted by light, but not in others. Wet-habitat species generally had positive photoblastic responses. For many species, scarification was effective to promote seed germination, but neither 100 nor 500 mg·L−1 GA3 had consistent promoting effects.
Paphiopedilum armeniacum S. C. Chen et F. Y. Liu is endemic to China and has great ornamental value. Little is known about its nutrient requirement for growth and reproduction after deflasking (transplantation of seedlings from culture vessels to pots). We studied the effects of adding nitrogen (N) (0, 105, 210, and 420 mg·L−1) on the vegetative growth and reproduction of P. armeniacum. N enrichment improved leaf area and lengthened the leaf lifespan during the vegetative stage. The effects of N application on flower size were minor. The intermediate N level of 210 mg·L−1 (MN) increased the seed capsule weight, seed germination rate, and improved the growth of seedlings that developed from seeds of MN-treated plants. N fertilizer exerted little influence on ramet emergence and ramet number per plant, but a low N concentration of 105 mg·L−1 promoted the leaf number and leaf area of ramets. Appropriate N levels for P. armeniacum in production and cultivation should be determined according to different production objectives.
Loquat (Eriobotrya japonica Lindl.) is an economically important subtropical fruit tree, originating and commercially produced mainly in China and Japan. The aseptic seed germination of 13 loquat cultivars, including 9 white-fleshed cultivars and 4 red-fleshed ones, was studied, and the relationship between the germination rate and the content of endogenous ABA in seeds was explored. The germination rate and the seedling height at 80 days after sowing of white-fleshed cultivars were generally higher than that of red-fleshed ones. The ABA content in seeds was generally lower in white-fleshed cultivars, and the ABA content negatively correlated with the germination rate at 80 days after sowing. A moderate detrimental effect of 75% ethanol disinfection on aseptic germination of loquat seeds was observed, especially, for the cultivar Dahongpao, and the germination rate and seedling height were reduced by around half and one-third, respectively. The addition of plant preservative mixture (PPM) to the germination medium at a final concentration of 25 mg·L−1 effectively controlled contamination when the 75% ethanol disinfection procedure was omitted.
Ethylene response factor (ERF) genes have been characterized in numerous plants, where they are associated with responses to biotic and abiotic stress. Modified atmosphere packaging (MAP) is an effective treatment to prevent lotus root browning. However, the possible relationship between ERF transcription factors and lotus root browning under MAP remains unexplored. In this study, the effects of phenol, phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) enzyme activities; and PPO, PAL, POD, and ERF gene expression on fresh-cut lotus root browning were studied with MAP. The expression pattern of ERF2/5 correlated highly with the degree of browning. It is suggested that NnERF2/5 can be used as an important candidate gene for the regulation of fresh-cut lotus root browning under MAP, and the correlation of each gene should be studied further.
Anthocyanins are protective pigments that accumulate in plant organs such as fruits and leaves, and are nutritionally valuable components of the human diet. There is thus considerable interest in the factors that regulate synthesis. Malus crabapple leaves are rich sources of these compounds, and in this study we analyzed leaf coloration, anthocyanin levels, and the expression levels of anthocyanin biosynthetic and regulatory genes in three crabapple cultivars (Royalty, Prairifire, and Flame) following various temperature treatments. We found that low temperatures (LTs) promoted anthocyanin accumulation in ‘Royalty’ and ‘Prairifire’, leading to red leaves, but not in ‘Flame’, which accumulated abundant colorless flavonols and retained green colored leaves. Quantitative reverse transcript PCR (RT-PCR) analyses indicated that the expression of several anthocyanin biosynthetic genes was induced by LTs, as were members of the R2R3-MYB, basic helix–loop–helix (bHLH) and WD40 transcription factor families that are thought to act in a complex. We propose that anthocyanin biosynthesis is differentially regulated in the three cultivars by LTs via the expression of members of this anthocyanin regulatory complex.
This study aimed to clarify the relationship between grape (Vitis vinifera L.) quality and environmental factors (climate and soil), and to elucidate the theoretical basis and provide technical guidance for the rational planning of the cultivation area and the precise regulation of the cultivation mode in the future. The fruits of three different grape cultivars, Pinot Noir, Merlot, and Vidal, as well as soil samples and meteorological data were collected from three wine grape growing areas (Wuwei, Zhangye, and Jiayuguan) in the Hexi Corridor, Northwest China. Principal-component analysis (PCA) and correlation analysis were conducted to understand the relationship of grape quality with weather conditions and soil properties. The results showed that the titratable acid content of grape berries was significantly negatively correlated with average temperature from August to September, average minimum temperatures from August to September, and from April to October, mean annual minimum temperature, growing degree days from August to September, and soil total nitrogen content, and significantly positively correlated with average rainfall from April to October, annual mean rainfall, and soil available potassium content. In addition, the pH of grape juice was significantly negatively correlated with annual mean rainfall and soil available potassium content. However, it was significantly positively correlated with average temperature and average minimum temperature from August to September, average minimum temperature from April to October, growing degree days from August to September, as well as soil total nitrogen content. In addition, the results of PCA showed that the fruit quality scores of ‘Vidal’ in Jiayuguan, ‘Merlot’ in Zhangye, and ‘Pinot Noir’ in Wuwei were the highest, respectively. In conclusion, the contents of titratable acid, pH, and Brix° are greatly affected by climate and soil factors. ‘Vidal’, ‘Merlot’, and ‘Pinot Noir’ were suitable for planting in Jiayuguan, Zhangye, and Wuwei, respectively. Nowadays, few reports focus on the relationship between grape quality and soil and climate conditions. Based on the investigation and analysis of the differences of climate, soil, and grape berries quality in the three production areas of Hexi Corridor, the relationship among climate, soil, and grape quality by using statistical methods was studied, which could provide references for clarifying the reasons why environmental factors affect grape quality and select the suitable area for wine grape cultivation.