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  • Author or Editor: Ming Xu x
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Heat is a major factor limiting growth of C3 grass species. Elevated CO2 may mitigate the adverse effects of heat stress or enhance heat tolerance. The objective of this study was to determine metabolic changes associated with improvement of heat tolerance by elevated atmospheric CO2 concentration in tall fescue (Festuca arundinacea). Plants (cv. Rembrandt) were exposed to ambient day/night temperature (25/20 °C) or heat stress (35/30 °C) and ambient CO2 concentration (400 ± 10 μmol·mol−1) or double ambient CO2 concentration (800 ± 10 μmol·mol−1) in growth chambers. Turf quality (TQ), shoot growth rate, and leaf electrolyte leakage results demonstrated that heat stress at ambient CO2 concentration inhibits turf growth and reduces cell membrane stability, whereas heat-stressed plants under elevated CO2 concentration exhibit improved TQ, shoot growth rate, and membrane stability. Plants exposed to heat stress under elevated CO2 exhibited a significantly greater amount of several organic acids (shikimic acid, malonic acid, threonic acid, glyceric acid, galactaric acid, and citric acid), amino acids (serine, valine, and 5-oxoproline), and carbohydrates (sucrose and maltose) compared with heat-stressed plants at ambient CO2. The increased production or maintenance of metabolites with important biological functions such as those involved in photosynthesis, respiration, and protein metabolism could play a role in elevated CO2 mitigation of heat stress damage. Therefore, elevated CO2 conditions may contribute to improved heat stress tolerance as exhibited by better TQ and shoot growth of heat-stressed plants. Practices to harness the power of CO2 may be incorporated into turfgrass management for plant adaptation to increasing temperatures, particularly during summer months.

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Lilium davidii var. unicolor Salisb is a cultivar of Lilium (Liliaceae) with important edible and ornamental characteristic. The application and production of Lilium davidii var. unicolor Salisb were still facing large problems because of its several disadvantages such as narrow range of adaptability, small annual growth increment, and low fertility. To achieve broader environmental adaptability and obtain a more nutritious germplasm, we used colchicine and oryzalin to induce chromosome doubling via the soaking method. Tissue culture bulbs were treated with colchicine at 0.03%, 0.05%, or 0.08% for 32, 40, or 48 hours or with oryzalin at 0.002%, 0.005%, 0.008%, or 0.01% for 3, 6, 9, 12, or 24 hours before being transferred to a differentiating medium. The results showed that colchicine treatment resulted in the highest induction rate when applied at 0.05% for 48 hours, whereas oryzalin treatment produced fewer tetraploid plants. The chromosome number of induced plants with small stoma density and longer guard cells is twice than that of the diploid. The plants were identified as tetraploid. In this study, a new germplasm of Lilium davidii var. unicolor Salisb was innovative and showed novel genetic characteristic.

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To improve plant quality and fertilizing efficiency, we conducted a study to elucidate the effects of nitrogen (N), phosphorous (P), and potassium (K) fertilizers on the growth, nutrient accumulation, and quality of Lagerstroemia indica plants grown in containers and determine the optimal fertilization levels. Both single-factor and multifactor experiments involving N, P, K fertilizers were designed. Integrated with the plant growth, physiological traits, nutrient levels, and other indices, we used a membership function analysis to comprehensively evaluate plant quality. During the single-factor experiments, the best levels of the single fertilizers applied were 8 g/plant N, 2 g/plant P, and 4 g/plant K. We also found that, within a certain range, N, P, and K fertilizers promoted vegetative growth, increased the chlorophyll, soluble sugar, and soluble protein concentrations, and enhanced nutrient accumulation of L. indica. To avoid the wasting of fertilizers and promote plant quality, the optimal application levels were calculated using a regression analysis. The suggested N, P, and K applications were 6.89 g/plant, 1.97 g/plant, and 3.33 g/plant, respectively. Our results revealed that N, P, and K effect the performance of L. indica container plants, which paves the way for developing reliable and precise fertilizing techniques for growing L. indica.

Open Access

The medicinal herb Withania somnifera (L.) Dunal (Solanaceae) was grown in two soilless systems to determine optimal conditions for production of biomass and withaferin A, the major secondary metabolite responsible for its claimed medicinal properties. Withaferin A content was analyzed using high-performance liquid chromatography (HPLC). The results show that there was no statistically significant difference (P > 0.05; t test) in biomass production between the plants grown aeroponically and hydroponically. Aeroponically grown plants produced an average of 49.8 g dried aerial plant material (DW) (sd 20.7) per plant, whereas hydroponically grown plants produced an average of 57.6 g DW (sd 16.0). In contrast, withaferin A content was statistically higher in plants grown hydroponically. These plants contained an average of 7.8 mg·g−1 DW (sd 0.3), whereas the aeroponically grown plants contained an average of 5.9 mg·g−1 DW (sd 0.6). These results demonstrate that hydroponic techniques are optimal in reproducibly and efficiently generating withaferin A. These findings may be of importance to the natural products industry in seeking to maximize production of biologically active compounds from medicinal plants.

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