Shoot elongation of `Stargazer' lily is rapid during the first 15 to 20 days after planting (1 to 2 cm·day–1 is common). Lower stem leaves are small, separated by long internodes. We determined if dipping `Stargazer' bulbs in uniconazole (5-, 10-, 20-, or 40-ppm solutions for 1 min) before planting would slow initial stem elongation, decrease final height, and improve appearance. Emergence, visible bud, anthesis dates, and flower bud count were recorded. Plant height was measured three times per week until anthesis. Uniconazole did not affect time to emergence, visible bud, anthesis, or flower bud count. Compared to the final height of 48 cm (untreated plants), height was reduced 7, 17, 22, and 30 cm (5%, 35%, 46%, and 62%) at anthesis for plants in the 5-, 10-, 20-, and 40-ppm treatments, respectively. The uniconazole bulb dips did not affect stem elongation rate for the first 10 days after treatment or from 45 days after treatment through anthesis (day 65). Relative to untreated plants, stem elongation rate of treated plants decreased linearly from 10 to about 35 days after treatment, with a maximum reduction of 55%, 75%, 85%, and 100% for plants in the 5-, 10-, 20-, and 40-ppm treatments, respectively.
Bin Liu and Royal D. Heins
Bin Liu and Royal D. Heins
The objectives of this study were to quantify the effects of the radiant-to-thermal energy ratio (RRT) on poinsettia plant growth and development during the vegetative stage and develop a simple, mechanistic model for poinsettia quality control. Based on greenhouse experiments conducted with 27 treatment combinations; i.e., factorial combinations of three levels of constant temperature (19, 23, or 27°C), three levels of daily light integral (5, 10, or 20 mol/m2 per day), and three plant spacings (15 × 15, 22 × 22, or 30 × 30 cm), from pinch to the onset of short-day flower induction, the relationship between plant growth/development and light/temperature has been established. A model for poinsettia quality control was constructed using the computer software program STELLA II. The t-test shows that there were no significant differences between model predictions and actual observations for all considered plant characteristics; i.e., total, leaf and stem dry weight, leaf unfolding number, leaf area index, and leaf area. The simulation results confirm that RRT is an important parameter to describe potential plant quality in floral crop production.
Bin Liu and Royal D. Heins
Plant growth and development are driven by two forms of energy: radiant and thermal. This study was undertaken to determine the effect of the ratio of radiant energy to thermal energy on plant quality of Euphorbia pulcherrima `Freedom'. Plants were grown under 27 combinations of temperature (thermal energy), light (radiant energy), and spacing, i.e., factorial combinations of three levels of constant temperature (19, 23, or 27°C:), three levels of daily light integral (5, 10, or 20 mol·m–2·d–1), and three levels of plant spacing (15 × 15, 22 × 22, or 30 × 30 cm), from pinch to the onset of short-day flower induction. Plants were treated for 450 degree-days (base temperature = 5°C) in Expt. 1 or 5 weeks in Expt. 2. The results showed that increasing radiant energy or decreasing average daily temperature during accumulation of 450 degree-days increased plant dry weight. When radiant and thermal energy were calculated into the ratio, plant dry weight increased linearly as the ratio increased Plants exposed to low light: levels and high temperatures, i.e., those at a low ratio, developed thin, weak stems. Higher radiant-to-thermal energy ratios produced thicker stems.
Bin Liu and Royal D. Heins
Photothermal ratio (PTR) is defined as the ratio of radiant energy (light) to thermal energy (temperature). The objective of this study was to quantify the effect of PTR during the vegetative (PTRv) and reproductive phase (PTRr) on finished plant quality of `Freedom' poinsettia. In Expt. I, plants were grown under 27 combinations of three temperatures, three daily light integrals (DLI), and three plant spacings from pinch to the onset of short-day flower induction and then moved to a common PTR until anthesis. In Expt. II, plants were grown under a common PTR during the vegetative stage and then assigned to nine combinations of one temperature, three DLIs, and three plant spacings after the onset of short-day flower induction. Both PTRr and PTRv affected final plant dry weight. All components of dry weight (total, stem, green leaf, and bract) responded in a linear way to PTRr and in a quadratic way to PTRv. Stem strength was more dependent on PTRv than PTRr. When PTRv increased from 0.02 to 0.06 mol/degree-day per plant, stem diameter increased about 24% while stem strength increased 75%. The size of bracts and cyathia was linearly correlated to PTRr, but not affected by PTRv. When PTRr increased from 0.02 to 0.06 mol/degree-day per plant, bract area, inflorescence diameter, and cyathia diameter increased 45%, 23%, and 44%, respectively.
Bin Liu and Royal D. Heins
Light (radiant energy) and temperature (thermal energy) affect quality of greenhouse crops. Radiant energy drives photosynthesis and, consequently, plant biomass accumulation. Thermal energy is the primary environmental factor driving developmental rate. The concept of a photothermal ratio (PTR), the ratio of radiant energy [moles of photosynthetic (400 to 700 nm) photons/m2] to thermal energy (degree-day), was proposed to describe the balance between plant growth and plant development in greenhouse crops. The objective of this study was to quantify the effect of PTR during vegetative (PTRv) or reproductive (PTRr) phases on finished plant quality of `Freedom' poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch). In Expt. 1, plants were grown under 27 combinations of three constant temperatures (19, 23, or 27 °C), three daily light integrals (DLIs) as measured by the number of photosynthetic (400 to 700 nm) photons (5, 10, or 20 mol·m-2·d-1), and three plant spacings (15 × 15, 22 × 22, or 30 × 30 cm) from pinch to the start of short-day flower induction, and then moved to a common PTR until anthesis. In Expt. 2, plants were grown under a common PTR during the vegetative stage and then moved to combinations of three DLIs (5, 10, or 15 mol·m-2·d-1) and three plant spacings (25 × 25, 30 × 30, or 35 × 35 cm) at a constant 20 °C from the start of short days until anthesis. Both PTRr and PTRv affected final plant dry weight (DW). All components of DW (total, stem, leaf, and bract) increased linearly as PTRr increased, and responded quadratically to PTRv, reaching a maximum when PTRv was 0.04 mol/degree-day per plant. Stem strength depended more on PTRv than PTRr. When PTRv increased from 0.02 to 0.06 mol/degree-day per plant, stem diameter increased ≈24%, while stem strength increased 75%. The size of bracts and cyathia increased linearly as PTRr increased, but was unaffected by PTRv. When PTRr increased from 0.02 to 0.06 mol/degree-day per plant, bract area, inflorescence diameter, and cyathia diameter increased 45%, 23%, and 44%, respectively.
Nuananong Purente, Bin Chen, Xiaowei Liu, Yunwei Zhou, and Miao He
Mutation breeding is considered to be economic and efficient in plant improvement, and the use of chemical mutagens such as ethyl methanesulfonate (EMS) can potentially address plant breeding challenges. The aim of this study was to induce morphological mutants in C. indicum var. aromaticum using EMS treatments with different doses, and to analyze the morphological and physiological traits of obtained mutants in expectation of finding favorable mutants. Results revealed significant effects of EMS doses on seed germination. The sample germination rate significantly decreased with increasing of EMS doses. The obtained morphological mutants were two viable types, containing leaf and stem mutants. Overall leaf size was significantly larger as a result of EMS treatments. And the height of mutant plants was significantly higher. Anatomical characteristics exhibited changes in both leaves and stems of the mutant plants. The puncture strength of the bent stem from the mutant plants was low, with weak penetration resistance. The total lignin and cellulose contents of mutant plants stem decreased significantly as a result of the EMS treatments. These results demonstrate the efficiency of EMS to induce mutations in C. indicum var. aromaticum, and this method can be useful in the future to assist breeding of this plant.
Bo-Ling Liu, Zhi-Bin Fan, Ze-Qun Liu, Xun-Hong Qiu, and Yan-Hong Jiang
Salvia miltiorrhiza (commonly known in China as Danshen) is widely used in traditional Chinese medicine, and it is applied in the treatment of many diseases, particularly cardiovascular disease. Commercial propagation of Danshen is carried out either through seed germination or in vitro regeneration (micropropagation). However, it is not clear if the different propagation methods affect the chemical properties of the derived plants. In the present study, we first established a highly efficient tissue culture system for Danshen propagation. The addition of 1.0 mg·L−1 6-benzyladenine (BA) and 0.1 mg·L−1 α-naphthalene acetic acid (NAA) to Murashige and Skoog (MS) medium was optimal for inducing adventitious shoots; the highest rate of rooting was recorded on MS medium with 0.2 mg·L−1 NAA, on which the survival rate of transplanted plantlets was 95%. Next, we assessed antioxidant properties in the different tissues of plants of the same age, derived from micropropagation or seed germination, and measured tanshinone, total phenol, and total flavonoid contents. Our results showed that tissues of micropropagated plantlets had higher antioxidant activities than tissues of seed-derived plantlets; the micropropagated plantlets also had higher tanshinone contents in their roots. Thus, a rapid and efficient micropropagation system was established for Danshen, and it can be used for cultivating this plant to obtain therapeutic compounds.
Yan Bai, Wen Chen, Shou-Zan Liu, Lin-Yu Xu, Zhe Li, and Bin Liu
Tetrastigma hemsleyanum is a traditional Chinese medicine herb, commonly used for its anti-inflammatory and antitumor properties. Flavonoids are the main functional constituents of T. hemsleyanum, and their production in the herb is affected by light quality. T. hemsleyanum is a shade-loving plant and is usually covered by black shade nets during cultivation. However, there are only a few studies on the effects of using color films on growth and flavonoid synthesis in T. hemsleyanum. In this study, we measured the influence of five different color films on growth indexes—sugar, soluble amino acid, soluble protein, and flavonoid content—and flavonoid-synthesizing enzyme activities in T. hemsleyanum. The films used were colorless plastic film as the control group (CK-W), red film (RF), yellow film (YF), green film (GF), and blue film (BF). BF promoted plant growth and increased yield, as evidenced by the highest growth indexes, soluble amino acid content, and chalcone isomerase (CHI) enzyme activity. RF increased the content of secondary metabolites, thereby enhancing herb quality, as evidenced by the highest phenylalanine ammonia lyase (PAL) activity and increased flavonoid content.
Yi Kai, Yang Bin, Zhang Min, Gao Ainong, Zhang Jinger, Liu Zhi, Sha Shoufeng, and Xie Chongxin
Meiling Yang, Fang Li, Hong Long, Weiwei Yu, Xiuna Yan, Bin Liu, Yunxiu Zhang, Guorong Yan, and Wenqin Song
As a wild apple species native to central Asia, Malus sieversii (Ledeb.) Roem. is distributed in a wide region covering most of the Tienshan Mountains. Malus sieversii is a useful genetic pool for apple breeding since rich with diversity. In this paper, we first describe the species range of this endangered species. We then describe an in situ reserve that has been established. We also investigated some reproductive characteristics of M. sieversii including pollen germination, seed dormancy, and seed viability. Both stratification and seedcoat removal efficiently released seed dormancy and accelerated seed germination. Pollen germination rate is around 60%. Our data suggest that injurious insects and human activities, rather than reproductive characters, limit the renewal of M. sieversii.