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The cultivation period of cassava in Kagoshima, Japan, which belongs to the temperate zone, is limited by the low temperature in winter. To maximize productivity under this limited period, investigations were conducted on the gas exchange rate and production structure relating to light utilization in a plant community of cassava grown under different nitrogen fertilization conditions. Fertilization either at planting or three months after planting significantly increased stomatal conductance in the upper canopy and root dry weight compared to the control. In addition, the dry matter distribution to stem and root dry matter rate of initial fertilization treatment were significantly higher, and the dry matter distribution to root of the latter fertilization treatment tended to be higher than that of the control. However, light transmittance at 80 cm below the top of the canopy was almost the same as that at the ground surface, which was a common tendency among the treatments. In conclusion, it was revealed that the effects of fertilization on yield were mainly the increase in the gas exchange rate of individual leaves and the change of dry matter distribution rather than an improvement in light transmittance.

Background Large-scale data on the photosynthetic characteristics of whole crop canopy is crucial for improving yield. However, current data collection methods remain challenging, and the time constraints associated with photosynthetic data collection further complicate matters. Developing a practical yet easy-to-use tool for collecting whole-canopy data is essential to address these challenges. Furthermore, it is necessary to obtain instantaneous measurements of photosynthetic rate over a wide range of CO 2 concentrations under an unsteady state to enable faster data collection and obtain reliable biochemical limits of carbon assimilation. This study developed a semi-open chamber system with steady and unsteady state measurement techniques to collect biochemical photosynthetic data from an entire cucumber canopy, emphasizing the correction procedures for CO 2 concentration of unsteady state measurements applicable regardless of chamber scale. Results After constructing a semi-open chamber system, we described how to correct measurement errors according to chamber volume. In order to assess the accuracy of the newly developed system, an analysis was conducted to determine the overall measurement error resulting from variations in the reference, sample CO 2 concentration, and leakage flow rate. The total measurement error was accurate to no more than 10%. Furthermore, the difference between the photosynthetic rate of the single leaf and that of the whole-canopy was not significant in Rubisco activity-limited carboxylation range. In addition, the Farquhar–von Caemmerer–Berry (FvCB) model parameters and the photosynthetic rate estimation values were compared to evaluate the steady- and unsteady state measurement methods between the cucumber seedlings' single-leaf and whole-canopy. The average root mean square error of the FvCB model in the steady (standard A-C i response) and unsteady states (800 to 400 ramp) of the chambers was 1.4 and 2.3, respectively. Results show that the developed system is suitable for measuring the gas exchange rate of the cucumber canopy. Conclusions We demonstrate the correction method for measurement errors to enable the gas exchange rate of the whole-canopy even in an unsteady state. The correction method of the measurement system of the gas exchange rate for the whole- canopy can be applied regardless of the volume of the chamber, and it can be applied simply to other chamber systems. In addition, an unsteady state measurement method for fast data collection was also applicable. However, it was deemed necessary to identify a more optimal measurement range by conducting measurements across a broader range of values.

The aim of this study was to establish a system of in vitro germination and propagation of Guazuma ulmifolia Lam. microcuttings (Malvaceae). Seeds were inoculated into test tubes containing different concentrations (half-strength (½) and fullstrength) of Murashige and Skoog (MS) basal salts and sucrose (0, 10, 20, 40, and 80 g L⁻¹). For the induction of multiple shoots, microcuttings were cultured on MS medium supplemented with 0.5, 1.0, and 2.0 mg L⁻¹ of 6-benzyladenine (BA), kinetin (KIN), or thidiazuron (TDZ), or containing no plant growth regulator (control). Nodal segments were also cultured in vessels with two different sealing systems, for example, sealed with a porous membrane (1 M) (21 µL L⁻¹ s⁻¹ of CO₂) or with no membrane (0 M) (14 µL L⁻¹ s⁻¹ of CO₂). Treatments with full-strength MS salts supplemented with 20% sucrose and ½ MS with 10% sucrose showed 100% germination, whereas there was no germination in the culture media with the highest sucrose concentration (80 g L⁻¹), regardless of the MS salt concentration. The presence of cytokinins in the culture medium reduced shoot length and number of leaves and roots in the microcuttings. Plants cultured in vessels sealed with a porous membrane showed greater total and shoot lengths and greater leaf area. Anatomical analyses also showed that the mesophyll and leaf blade were thicker in plants cultured under higher gas exchange (1 M), a condition that also favored ex vitro plant acclimatization. These results provide relevant information for the establishment of G. ulmifolia micropropagation systems.

Eryngium foetidum L., a biennial herb with diverse applications in food and traditional medicine, holds economic and pharmacological significance. Given its growing commercial interest, implementing biotechnological approaches like plant tissue culture is vital for sustainable propagation and metabolite production. In this study, we investigated the in vitro photoautotrophic potential of Eryngium foetidum, examining growth, chlorophyll a fluorescence, photosynthetic pigments, and anatomical features under sucrose concentrations (0 and 30 g L−1) and gas exchange rate (14 and 25 μL L−1 s−1 CO2). Acclimatization and survival rates of plants after ex vitro transfer were also assessed. Eryngium foetidum exhibited robust growth in both photoautotrophic and photomixotrophic conditions, with natural ventilation significantly enhancing plant development. Chlorophyll a fluorescence and photosynthetic performance were influenced by sucrose and gas exchange, highlighting the importance of these factors in plant micropropagation. Moreover, the species demonstrated remarkable plasticity during acclimatization, with high survival rates and rapid inflorescence development. The research provides valuable insights into optimizing in vitro cultivation conditions for Eryngium foetidum, emphasizing the potential for large-scale clonal propagation and exploring secondary metabolites. The observed phenotypic plasticity underscores the adaptability of the species to diverse environments. These biotechnological strategies open avenues for future studies, including the application of elicitors for enhanced secondary metabolite production.

Silicon (Si) accumulation in plants is widely recognised as an effective physical defence against chewing herbivores. However, its effects on some feeding guilds such as cell-content feeders are understudied despite being severe economic pests (e.g. Tetranychus urticae ). Moreover, most studies focus on direct impacts of Si, but there is growing evidence that Si also impacts indirect defence. We examined the effects of Si on French bean, Phaseolus vulgaris , defences against the two-spotted spider mite, T. urticae . We grew plants hydroponically with (+ Si) or without (–Si) silicon, assessed T. urticae performance and tested the preference of the predatory mite, Phytoseiulus persimilis , for volatiles from T. urticae -infested (+ M) or uninfested (–M) plants. The provision of Si to plants suppressed T. urticae egg-laying, population growth and leaflet damage, and partially ameliorated T. urticae -induced reductions in stomatal conductance and net photosynthesis. Furthermore, T. urticae infestation increased foliar Si accumulation. Predatory mites were more attracted (64%) to volatiles from + Si plants experiencing herbivory than to –Si plants. The relative emissions (%) of volatile compounds, viz. E -2-hexanyl benzoate, hexanal, E-trans -β-ocimene, D-limonene, β-caryophyllene and methyl salicylate were elevated from + Si + M plants, while the relative emissions of 3-hexanol, trans -calamenene, o -xylene and o -cymene were lowered compared to –Si + M plants. Our results show, for the first time, that Si defences are inducible and effective even in low Si-accumulating plants against T. urticae and suggest that Si could play a role in pest biocontrol.

1. The aim of the study was to investigate effects of enhanced UV‐B radiation on the balance between biomass production and decay in an ombrotrophic bog which is dominated by one species of Sphagnum (S. fuscum). This paper concerns production. 2. Enhanced UV‐B radiation (simulating 15% ozone depletion under clear sky conditions) was applied by means of fluorescent tubes during two growing seasons. 3. In S. fuscum, shoot density, mass relations and length increment over time were measured and productivity was estimated. Pigment concentration, rates of dark respiration and maximum net photosynthesis were recorded. 4. Sphagnum fuscum productivity was not changed by enhanced UV‐B radiation while properties determining production were highly influenced although in opposite directions. 5. Height increment was decreased by 20% in the first growing season and by 31% in the second growing season under enhanced UV‐B radiation. After two growing seasons spatial shoot density was decreased by 8% by enhanced UV‐B radiation. The shoots became stunted as capitulum dry mass and stem dry mass per unit length were increased by 21 and 17%, respectively, under enhanced UV‐B radiation. 6. Dark respiration was significantly decreased by 31% after growth under enhanced UV‐B radiation. 7. The UV‐B induced change in shoot biometry together with the reduced spatial shoot density involve potential long‐term effects on peat structure with possible feedback on productivity, decomposition and the strength of the system as a carbon sink.

Gypsophila paniculata L. is one of the most important commercial cut flowers worldwide. The plant is sterile and propagated mainly by in vitro culture techniques. However, hyperhydricity hinders its micropropagation and increases mortality during ex vitro acclimatization. Hyperhydric shoots of G. paniculata were proliferated from nodal explants on MS medium without growth regulators that contained 30 g L−1 sucrose, and gelled with 6.0 g L−1 agar. Medium components and environmental culture conditions were optimized to revert hyperhydricity in G. paniculata microshoots and develop an efficient micropropagation protocol for commercial production. Multiple shoots with high quality were successfully regenerated on MS medium fortified with potassium and ammonium nitrate at full concentration, 2.0 mg L−1 paclobutrazol, solidified with 9.0 g L−1agar in Magenta boxes of 62.87 gas exchange/day and incubated under light density of 60 µmol m−2s−1. We recorded 4.33 shoots, 40.00 leaves, 6.33 cm, 2.50 g and 95.00% for number of shoots/explant, number of leaves/shoot, shoot length, shoot fresh weight and normal shoots percentage, respectively. Well-rooted plantlets of G. paniculata were developed from the reverted microshoots, with the rooting percentage (95.00%) on MS medium augmented with 1.0 mg L−1 IBA in Magenta boxes of 62.87 gas exchange/day and 60 µmol m−2s−1 light density. In vitro-rooted plantlets exhibited reduced electrolyte leakage, and enhanced antioxidant enzymes activity of peroxidase, catalase, and polyphenol oxidase due to good ventilation at the highest gas exchange rate of the culture vessels.

Development of a water-efficient irrigation system is essential in order to cultivate Jatropha curcas, a bioenergy crop, in semiarid regions. In the present study, to determine the useful parameter for the efficient irrigation system, jatropha plants were grown in pots and root boxes under greenhouse conditions in Okinawa, Japan. At 6 to 9 months after transplanting, we measured the gas exchange rate during ongoing soil water deficits and attempted to identify the threshold of soil matric potential (pF) with changes of both intrinsic water use efficiency ( A/gs ) as a stomatal-based index and carboxylation efficiency ( A/C i ) as an index of non-stomatal limitation. When irrigation was stopped, A and gs began to decline, with each parameter reaching zero at pF 4.0. However, gs was more sensitive to soil water deficits than A . After re-watering, stomatal openings and carbon uptake recovered to the value observed before water stress treatment. At pF 3.5 and higher values (representing more severe water stress), A/gs intended to increase and A/C i sharply decreased. These results suggested that approximately pF 3.5 in the soil was the threshold of non-stomatal limitations to photosynthetic rate and should be useful to the re-watering point for the water-efficient irrigation system in jatropha. CO 2 assimilation rate; C i : intercellular CO 2 concentration; E: transpiration rate; g s : stomatal conductance; pF: soil matrix potential; PFD: photon flux density; TDR: time domain reflectometry; VPD: leaf-to-air vapor pressure difference; VWC: volumetric water content.

One unresolved challenge in the egg industry is how to efficiently and non-invasively detect unfertilized eggs prior to incubation. This detection ability would not only significantly improve hatching rates and reduce costs but also conserve incubator space and prevent poor-quality embryos from contributing to the spread of infections. This study demonstrates a procedure for distinguishing between fertilized and unfertilized eggs prior to incubation by studying the respiratory differences between fertilized and unfertilized eggs using the Non-invasive Micro-test Technique (NMT). A customized micro-testing examination platform, NMT Egg Testing System (NMT-ETS) was constructed for the real-time monitoring of the intensity and rate of oxygen exchange between the egg and its external environment. The results from this study revealed that at room temperature, there is a significant difference in gas exchange rates between fertilized and unfertilized eggs. The results indicate that the oxygen flux of fertilized eggs exceed 20 pmol/(cm2.s), whereas unfertilized eggs show a much lower oxygen flux. Based on the results, the NMT method can be used to effectively distinguish between fertilized and unfertilized chicken eggs.

The objective of the present study was to examine the functional coordination among hydraulic traits, xylem characteristics and gas exchange rates across three deciduous Euphorbiaceae tree species (Hevea brasiliensis, Macaranga denticulata and Bischofia javanica) and three evergreen Euphorbiaceae tree species (Drypetes indica, Aleurites moluccana and Codiaeum variegatum) from a seasonally tropical forest in south-western China. The deciduous tree species were more vulnerable to water stress-induced embolism than the evergreen tree species. However, the deciduous tree species generally had higher maximal rates of sapwood and leaf-specific hydraulic conductivity (K S and K L), respectively. Compared with the evergreen tree species, the deciduous tree species, however, possessed a lower density of sapwood and a wider diameter of xylem vessels. Regardless of leaf phenology, the hydraulic vulnerability and conductivity were significantly correlated with sapwood density and mean vessel diameter. Furthermore, the hydraulic vulnerability was positively correlated with water transport efficiency. In addition, the deciduous tree species exhibited higher maximal photosynthetic rates (A max) and stomatal conductance (g max), but lower water use efficiency (WUE). Interestingly, the A max, g max and WUE were strongly correlated with K S and K L across the deciduous and evergreen tree species. These results suggest that xylem structure, rather than leaf phenology, accounts for the difference in hydraulic traits between the deciduous tree species and the evergreen tree species. Meanwhile, our results show that there is a significant trade-off between hydraulic efficiency and safety, and a strong functional correlation between the hydraulic capacity and gas exchange rates across the deciduous and evergreen tree species.