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Root-zone temperature (RZT) is an indispensable environmental factor for the proper growth and development of plants. Low RZT is one of the major limitations for agricultural production during cold seasons. In this study, the physiological responses of tomato seedlings to low RZT stress (10 °C) and its recovery were investigated with hydroponic cultivation in an artificial climate-controlled chamber. The stress reaction of tomato seedlings was evaluated by combining various indexes, including photosynthesis, chlorophyll fluorescence, root activity, hydrogen peroxide, and antioxidants. The results showed that low RZT adversely affected root activity, and in response to the limited root-source water and mineral elements, supply for shoot metabolism, leaf photosynthesis, and chlorophyll fluorescence were negatively influenced, which led to inhibited leaf area development and biomass accumulation. Hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline accumulated with the time of low RZT stress. When restored to normal temperature (∼20 °C), the physiological parameters recovered to a certain degree, although most parameters were not at a similar level with the control. In crop production during cold seasons, it is necessary to improve the RZT to achieve high quality and yield production.
Long-term exposure to an elevated ambient carbon dioxide (eCO2) concentration could weaken or diminish the enhancement of plant photosynthesis and growth. To monitor this response and offer references for growth management, the whole-plant photosynthetic rate (P n,w ) and dark respiration rate (R d,w ) of Angelica acutiloba Kitagawa transplants were monitored with a growth chamber. The results showed that eCO2 increased both the P n,w and R d,w by (79 ± 42) % and (126 ± 51) %. The dry weight of transplants under eCO2 was 33.6% greater than that under aCO2. However, the photosynthetic acclimation to eCO2 occurred. The increase in the P n,w was maintained until the end of the experiment due to increased leaf area. Moreover, the increase in plant dry weight mainly occurred in the first 15 days of treatment. Furthermore, the dry weight estimated based on the P n,w and R d,w agreed well with the measured dry weight. The relative growth rate (RGR) calculated with the estimated dry weight demonstrated the response of transplant growth to eCO2. These results indicated that the proposed method can be used to monitor the response of plant growth to eCO2.
Plant growth and development relies on light and is influenced by light. Light-emitting diode (LED) technology is nowadays providing the possibility for regulating plant growth and development by modifying light spectral composition. Many researches have been carried out to figure out the effects of light quality on various aspects of plant behaviors, including plant morphology, physiology, and biochemistry. In this review, we summarized those research outputs, in order to give suggestion of light quality application for both research and production purposes, in the field of productional yield, productional quality for horticultural plants including vegetables or ornamentals in difference with cultivation goals.
In this study, Dianthus caryophyllus L. was used as the experimental plant to investigate the effects of rooting substrate and exogenous auxin concentration on the adventitious rooting of the stem cuttings. Our results showed that the formulated substrates with different physicochemical properties significantly affected the root formation. The substrate with a ratio of cocopeat to perlite at 1:1 (v:v) resulted in the optimum rooting of D. caryophyllus cuttings. Different Indole-3-butyric acid (IBA) and 1-naphthalene acetic acid (NAA) concentrations affected the rooting percentage and seedling rate of D. caryophyllus. Application of NAA at 1000 mg·kg−1 with IBA at 100 mg·kg−1 resulted in the greatest rooting percentage and improved breeding speed. The rooting percentage and seedling rate did not increase with the increase in auxin concentration. Based on these results, we concluded that an appropriate rooting substrate is required to fulfill proper rooting of D. caryohhyllus cuttings, whereas an exogenous application of IBA and NAA at 1000 mg·kg−1 and 100 mg·kg−1 promoted the rooting and a higher auxin concertation inhibited rooting.