This study aimed to investigate the flowering biological characteristics, floral organ characteristics, and pollen morphology of Camellia weiningensis Y.K. Li. These features of adult C. weiningensis plants were observed via light microscopy and scanning electron microscopy (SEM). Pollen viability and stigma receptivity were detected using 2,3,5-triphenyltetrazole chloride (TTC) staining and the benzidine–hydrogen peroxide reaction method. C. weiningensis is monoecious, with alternate leaves and glabrous branchlets. Its flowering period lasts 2 to 4 months, and the flowering time of individual plants lasts ≈50 days, with the peak flowering period from the end of February to the middle of March. It is a “centralized flowering” plant that attracts a large number of pollinators. Individual flowers are open for 12 to 13 days, mostly between 1230 and 1630 hr, and include four to six sepals, six to eight petals, ≈106 stamens, an outer ring of ≈24.6-mm-long stamens, an inner ring of ≈13.4-mm-long stamens, one pistil, and nine to 12 ovules. The flowers are light pink. The style is two- to three-lobed and 16.6 mm long, showing a curly “Y” shape. The contact surface of the style is covered with papillary cells and displays abundant secretory fluid and a full shape, facilitating pollen adhesion. The pollen is rhombohedral cone-shaped, and there are germ pores (tremoids). The groove of the germ pore is slender and extends to the two poles (nearly reaching the two poles). The pollen is spherical in equatorial view and trilobate in polar view. The pollen vitality was highest at the full flowering stage, and the stigma receptivity was greatest on days 2 to 3 of flowering. The best concentration of sucrose medium for pollen germination was 100 g/L. The number of pollen grains per anther was ≈2173, and the pollen-to-ovule ratio was 23,034:1. C. weiningensis is cross-pollinated. Seventy-two hours after cross-pollination, the pollen tube reached the base, and a small part entered the ovary. The time when the pollen tube reached the base after pollination was later than that in commonly grown Camellia oleifera. The results of this study might lay an important foundation for the flowering management, pollination time selection, and cross-breeding of C. weiningensis.
Hongli Wei, Chao Gao, Jie Qiu, Li Long, Biao Wang, Lu Yang, and Yang Hu
Saki Toshima, Marika Fujii, Momoko Hidaka, Soya Nakagawa, Tomonari Hirano, and Hisato Kunitak
Interspecific hybridization is useful in raspberry (Rubus idaeus L. ssp. idaeus) breeding to introgression of traits such as heat or cold tolerance, and excellent fruit qualities. Rubus L. wild species in Asia, including Rubus parvifolius L., have been attracting a great deal of attention as sources of new traits in breeding raspberry and blackberry (Rubus fruticosus Agg.). We previously developed and selected IPI-1 and IPI-3 first backcross (BC1) hybrids, [‘Indian Summer’ (R. idaeus ssp. idaeus) × R. parvifolius] × ‘Indian Summer’, as raspberry cultivars adapted to the warm climate in parts of Japan. In this study, we investigated the growth, morphological traits, and fruit qualities, such as sugar, organic acid, anthocyanins, and carotenoids, of each of these IPI lines over a 2-year period to discern their potential as commercial raspberry cultivars. IPI lines had the characteristic of primocane fruit with overflowing from side buds while the parent, IP-1 (‘Indian Summer’ × R. parvifolius), did not. IPI lines showed significantly lower values in anthocyanin content than red raspberry ‘Skeena’, while showing higher carotenoid contents. This study is the first research about fruit qualities such as anthocyanin and carotenoid content of BC1 hybrids using Japanese wild Rubus species.
Xiangli Ma, Min Tang, Yufen Bi, and Junbo Yang
Cymbidium tortisepalum is a primary orchid species in Yunnan Province, China, and has an extremely high ornamental and economic value. To reveal the levels and distribution of genetic variation and structure of wild C. tortisepalum resources, sequence variations of six chloroplast DNA intergenic spacers (psbM-trnD, trnV-trnA, accD-psal, rrn23, trnk-rps16, and ycf1) were analyzed in 404 wild individuals from 28 populations in the three river area in Yunnan Province, China. The results showed that the six chloroplast DNA sequences were aligned with 61 polymorphic sites, including 50 indels and 11 haplotypes in 404 individuals, which revealed a low level of genetic diversity (total genetic diversity = 0.240, and the average value of nucleotide diversity = 0.00024). In addition, a fairly low genetic differentiation [coefficients for genetic differentiation among populations (GST) = 0.099, number of substitution (NST) = 0.081] was found among the studied populations, and NST value was less than GST, which indicated that no significant phylogeographic structure existed in those populations. Furthermore, analysis of molecular variance revealed that great genetic variance (91%) came from individuals within the populations, which indicated that there was no clear genetic differentiation among populations. On the basis of these findings, a conservation plan was proposed to sample or preserve fewer populations but with more individuals from each population.
Lulu Zhang, Yijun Yin, Yunfei Mao, Yeping Liu, Huiling Pang, Xiafei Su, Yanli Hu, and Xiang Shen
Tong Zhang, Yingjie Yan, Chuantong Li, Junmei Liu, Dongxue Yin, Xiangying Xiong, Wei Liu, and Yueqin Yang
This study investigated the effects of illumination time and soil moisture on seed germination and seedling establishment of Magnolia sprengeri Pamp. to improve the seed germination percentage and seedling survival percentage of M. sprengeri. It is of great significance for rapid propagation, seedling regeneration, field management, and artificial high-efficiency cultivation of M. sprengeri. In this study, the seeds of natural M. sprengeri populations from original habitat were used as test materials. Seed germination and seedling establishment of M. sprengeri were performed under different illumination time and soil moisture treatments in artificial climate incubator. The study found that there were significant differences among various key parameters related to seed germination and seedling establishment under different treatments (P < 0.05). Germination percentage, germination potential, germination index, vigor index, germination rate, plant height, number of leaves, base diameter, taproot length, number of lateral roots, maximum lateral root length, single plant leaf area, fresh weight, and seedling survival rate reached the maximum at continuous illumination and 13% of soil moisture, respectively. By the integrative evaluation for the influence of these two factors on seed germination and seedling establishment, soil moisture is a dominant factor affecting seed germination and seedling establishment, whereas illumination is an important promoting factor for seedling establishment of M. sprengeri. Continuous illumination and 13% of soil moisture content is suitable for seed germination and seedling establishment of M. sprengeri.
David R. Bryla, Carolyn F. Scagel, Scott B. Lukas, and Dan M. Sullivan
Excess salinity is becoming a prevalent problem for production of highbush blueberry (Vaccinium L. section Cyanococcus Gray), but information on how and when it affects the plants is needed. Two experiments, including one on the northern highbush (Vaccinium corymbosum L.) cultivar, Bluecrop, and another on the southern highbush (V. corymbosum interspecific hybrid) cultivar, Springhigh, were conducted to investigate their response to salinity and assess whether any suppression in growth was ion specific or due primarily to osmotic stress. In both cases, the plants were grown in soilless media (calcined clay) and fertigated using a complete nutrient solution containing four levels of salinity [none (control), low (0.7–1.3 mmol·d−1), medium (1.4–3.4 mmol·d−1), and high (2.8–6.7 mmol·d−1)] from either NaCl or CaCl2. Drainage was minimized in each treatment except for periodic determination of electrical conductivity (EC) using the pour-through method, which, depending on the experiment, reached levels as high as 3.2 to 6.3 dS·m−1 with NaCl and 7.8 to 9.5 dS·m−1 with CaCl2. Total dry weight of the plants was negatively correlated to EC and, depending on source and duration of the salinity treatment, decreased linearly at a rate of 1.6 to 7.4 g·dS−1·m−1 in ‘Bluecrop’ and 0.4 to 12.5 g·dS−1·m−1 in ‘Springhigh’. Reductions in total dry weight were initially similar between the two salinity sources; however, by the end of the study, which occurred at 125 days in ‘Bluecrop’ and at 111 days in ‘Springhigh’, dry weight declined more so with NaCl than with CaCl2 in each part of the plant, including in the leaves, stems, and roots. The percentage of root length colonized by mycorrhizal fungi also declined with increasing levels of salinity in Bluecrop and was lower in both cultivars when the plants were treated with NaCl than with CaCl2. However, leaf damage, which included tip burn and marginal necrosis, was greater with CaCl2 than with NaCl. In general, CaCl2 had no effect on uptake or concentration of Na in the plant tissues, whereas NaCl reduced Ca uptake in both cultivars and reduced the concentration of Ca in the leaves and stems of Bluecrop and in each part of the plant in Springhigh. Salinity from NaCl also resulted in higher concentrations of Cl and lower concentrations of K in the plant tissues than CaCl2 in both cultivars. The concentration of other nutrients in the plants, including N, P, Mg, S, B, Cu, Fe, Mn, and Zn, was also affected by salinity, but in most cases, the response was similar between the two salts. These results point to ion-specific effects of different salts on the plants and indicate that source is an important consideration when managing salinity in highbush blueberry.
Marzieh Keshavarzi, Keith A. Funnell, David J. Woolley, and Julian A. Heyes
We investigated the possibility of either exogenous ethylene or endogenous ethylene production having an association with the increase in shoot number when nodal explants of Gentiana spp. ‘Little Pinkie’ were cultured in an in vitro medium supplemented with ethephon (10 mg⋅L–1). For the first time within an in vitro system, we report the application of laser ethylene detector technology, and optimization of the methodology to quantify concentrations of ethylene (in the part-per-billion range) released from ethephon decomposition within the atmosphere of gas-exchangeable culture vessels including nodal explants. Compared with continuous (continuous measurements on the same replicate of vessels) and repeated (sampling same replicate of vessels every 48 hours) sampling methodologies, the nonrepeated (sampling fresh replicate of vessels every 48 hours) method of measurement of ethylene concentration was more representative of the actual condition within vessels. Although no prior published data exist showing the positive or negative effect of gaseous ethylene in the headspace of culture vessels on bud outgrowth in gentian, our study shows gaseous ethylene in the headspace of culture vessels was not effective in increasing shoot formation in gentian explants cultured in vitro, whereas ethephon supplementation in agar was effective. Plant material in culture vessels did not have a significant effect on ethylene production regardless of the presence or absence of ethephon. Therefore, although ethephon supplementation in the medium produced gaseous ethylene in the headspace, it was unlikely to cause endogenous ethylene production in explants, but it did trigger shoot formation in ‘Little Pinkie’, perhaps through decomposition to ethylene within the explant tissue, enhancing the internal ethylene level possibly at a locally high concentration.
Huihui Zhang, Ping Yu, Min Song, Dalu Li, Qianqian Sheng, Fuliang Cao, and Zunling Zhu
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.