An in vivo method to promote adventitious bud formation in leaf apex explants of Begonia×tuberhybrida was developed based on exogenous treatment with BA, IAA and NAA. Endogenous IAA concentrations of the leaf blade were highest in the apical portion, followed by the middle and basal portions. Treatment with 0.5 mg L−1 BA increased the percentage of adventitious bud formation to 15% from 0% at 0 mg L−1 BA, but treatment with BA at concentrations higher than 0.5 mg L−1 had no additional promotive effect. Adventitious bud formation was increased to 53% by treatment with 0.1 mg L−1 IAA and 0.5 mg L−1 BA, and inhibited by 1.0 and 5.0 mg L−1 IAA. The optimal duration of treatment with 0.1 mg L−1 IAA was 2–8 days after embedding. No explants formed adventitious buds when treated with fresh 0.1 mg L−1 IAA at 2-day intervals until 16 days after initial embedding. Similar responses were observed in explants treated with 0.1 mg L−1 NAA. These results suggested that temporary IAA treatment at 0.1 mg L−1 during the initial period of embedding is an efficient in vivo method to induce adventitious bud formation in leaf apex explants in B.×tuberhybrida.
To compare the effect of lowering solution temperature and the application of germicides at higher temperatures, cut rose flowers were placed in vases containing distilled water (DW) or isothiazolinonic germicides, a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (CMIT/MIT) solution. Vase solutions were kept at 10 and 23°C under an air temperature of 23°C or at 10 and 30°C under an air temperature of 30°C. Lowering the vase solution temperature significantly extended the vase life of cut roses at an air temperature of 30°C but not at an air temperature of 23°C. Treatment with CMIT/MIT significantly extended the vase life of cut roses at both air temperatures. CMIT/MIT treatment delayed the time to the start of the decrease in fresh weight more than did lowering vase solution temperature at both air temperatures. Stem hydraulic conductance of cut flowers held in DW at 23 and 30°C decreased with time. The decrease in hydraulic conductance was suppressed by CMIT/MIT treatment more than by lowering the vase solution temperatures at both air temperatures. These results show that CMIT/MIT treatment is more effective than lowering the temperature of vase water for extending the vase life of cut roses.
To evaluate the role of methyl jasmonate (MeJA) on ozone (O3: 0, 0.1, 0.3 cm3 m−3; abbreviated respectively as O0, O0.1 and O0.3)-induced photosynthetic inhibition of rice leaves at different atmospheric carbon dioxide (CO2) concentrations (400 and 800 cm3 m−3; abbreviated respectively as C400 and C800), MeJA solutions (0, 10, 100 μM; abbreviated respectively as M0, M10, and M100) were applied one day before acute exposure (5 h) of O3. Gas exchange, chlorophyll fluorescence and ascorbic acid were measured immediately before (BE), immediately after (AE-0), and 1 d and 3 d after (AE-1, AE-3) O3 exposure. The net photosynthetic rate (PN), and maximum (Fv/ Fm) and operating (Fq′/Fm′) quantum efficiencies of photosystem II (PSII) were decreased by O3 exposure at AE-0. However, MeJA ameliorated the O3-inhibition of Fv/Fm and Fq′/Fm′ of PS II. Rapid recovery from O3-inhibition of PN was observed as a result of MeJA application, but MeJA decreased the PN and stomatal conductance (gs) at AE-0. The O3 decreased the total ascorbic acid content, although the MeJA increased it. The effects of MeJA on the O3-inhibition of PSII and ascorbic acid content at C800 were less than at C400.
Growth performance and water use efficiency (WUE) of wheat in loamy sand treated with various proportions of silt loam were investigated by executing field experiments consisting of five soil treatments. The treatments were: (i) T1: loamy sand (6.04% clay) (control), (ii) T2: sandy loam (8.50% clay), (iii) T3: loam 1 (9.04% clay), (iv) T4: loam 2 (10.00% clay), and (v) T5: silt loam (13.00% clay) (amendment as a source of clay). Wheat was cultivated in two consecutive growing seasons with four irrigations and an identical recommended fertilizer dose. The leaf area index, plant height, number of tillers per plant, spike length, number of spikelets per spike, number of grains per spike, and yields (grain and biomass) significantly (P=0.05) improved in the amended treatments compared to the control. The amended treatments (T2–T5) produced 1.2–2.9 and 1.2–2.8 times more grain and biomass yields, respectively compared to T1. The WUE increased progressively with increasing quantity of clay in the treatments; the amendment saved 30 to 60% irrigation water compared to T1. The treatment T4 producing significantly improved leaf area index, grain and biomass yields, and WUE appeared to be the best soil texture for wheat cultivation. Soil amendment thus improved agricultural productivity of loamy sand by improving its water regimes.
A method of measuring spectral-induced polarization (SIP) by employing an SR810 DSP lock-in amplifier has been proposed. The method, to be used for characterizing soils, was calibrated with known resistors, and tested for a resistive-capacitive (RC) circuit, which closely simulated a soil sample in terms of its electrical properties. A suitable sample-electrodes configuration was selected by evaluating the impedance spectroscopy of three pairs of current electrode and seven pairs of potential electrode. The current electrodes conduct a launched sinusoidal current wave and the potential electrodes provide the voltage at their locations. The method imparted negligible influence of capacitive coupling below 100 Hz frequency of the applied electric field, and measured voltage phase (φ(ω)) within 1 mrad accuracy; the noise level in the measurement was the least at <10 Hz frequency. An input current density of 0.35 A/m2 induced negligible noise in φ(ω) and was found optimum for the method. The resistance-dependent response of the circuit elements affected the phase and impedance spectra of the RC circuit, and hence a correction for the system's transfer function was employed. A geometric factor arising from the sample-electrodes configuration was found independent of frequency of the electric field and conductivity of the sample. The current electrodes of porous bronze plate generated negligible φ(ω) below 100 Hz frequency and were superior to chrome nickel and platinum electrodes. The potential electrodes of platinum, titanium and stainless steel rods resulted in the negligible surface polarization below 100 Hz frequency, with the superior result by the platinum electrodes. The lock-in amplifier can thus reliably measure SIP from suitable sample-electrodes configurations.
Virus vector-mediated transgene expression enables rapid pharmaceutical protein production using plants, such as hemagglutinin (HA), a vaccine antigen of influenza virus. Here, effects of air temperature and photosynthetic photon flux density (PPFD) from the transgene introduction to harvest on recombinant HA content in Nicotiana benthamiana leaves were investigated. A deconstructed tobamovirus-based vector system (magnICON) was used for transient expression of HA. Plants were incubated at a PPFD of 100 (LP) or 300 (HP) μmol m−2 s−1 and an air temperature of 20 (LT) or 25 (HT) °C for 6 d after transgene introduction. At the harvest, high-level accumulation of intact HA of approximately 75 kDa was detected in leaves. Leaf HA content per unit dry weight in LT was three-times greater than that in HT. There was no significant difference in HA content between LP and HP regardless of temperature. The greater HA content in LT was positively correlated with a greater total soluble protein content, suggesting that not only HA but overall soluble proteins including HA were greater in LT than in HT. Thus, air temperature for plant incubation after transgene introduction can be a crucial environmental factor for HA productivity in virus vector-mediated transient expression systems.
New hydroxyapatite (HAp)-like compounds have been previously synthesized by reacting oyster shell powder (Oys) with (NH4)2HPO4 and Ca(OH)2 at 25–28°C (OyOHr) and 100°C (OyOHh). In this study, the effects of these compounds on the immobilization of cadmium (Cd) in soil were investigated as a function of their reaction time with soil. Oys, CaCO3, HAp, OyOHr, and OyOHh were each mixed well with soil and cadmium sulphate. They were then put into plastic pots and incubated at 15–30°C for 56 days with periodical watering. After 56 days, soils with OyOHr or OyOHh only leached 8–10% of the Cd added, whereas soils without addition leached 25%. The suppressive effect of the compounds on Cd uptake by lettuce (Lactuca sativa L.) was also examined using the soils with different reaction times with OyOHr or OyOHh for pot cultivation. In all the treatments, the Cd contents in shoots and roots decreased with soil incubation time with the Ca materials. In the soil incubated for 56 days, the Cd content in shoots was lowest with OyOHh where Cd uptake was suppressed by 48% compared with a control with no added Ca material.
The effects of culture conditions on the formation and growth of adventitious bud derived from hairy roots of Atropa belladonna L. were investigated. Various concentrations of kinetin (KN) alone were prepared in combination with Murashige and Skoog (MS) and Gamborg's B5 (B5) media. Although the number and weight of adventitious buds were increased in MS medium, no marked effects by KN were shown. In the effects of sucrose concentrations, the number and weight of adventitious buds were most increased at 1% sucrose in MS medium. In the effects of inorganic components in MS medium, the strengths of inorganic solutions were modified, but the results were almost the same as a whole. The strong effects of ammonium nitrogen and thiamine were assumed in comparison with B5 medium. For inhibition of clump formation by shear conditions, independent adventitious buds were observed from 100 rpm rotary speed. Under the highest speed at 140 rpm, whereas the weight of adventitious buds was decreased, we found that the number was most increased as a positive effect of shear stress. Furthermore, multiple shoots with roots were regenerated from minute adventitious buds, so the possibility of mass seedling production from hairy roots of A. belladonna was suggested.
The objective of this study was to establish a cultivation method for leafy vegetables and tomatoes with low potassium content for dialysis patients who are restricted potassium intake, while still maintaining normal plant growth. Three types of leafy vegetables were grown hydroponically with no potassium application during the latter half of their growth period. Tomatoes were grown hydroponically under two different conditions 1) in a nutrient solution without potassium, and 2) in a nutrient solution alternated every week with and without potassium. The potassium content of leafy vegetables in the potassium restricted group was 30–40% of the control, with no change in plant growth. The potassium content of the tomatoes in the potassium restricted group was also reduced to 50–89% of the control. There was no change in the fresh weight per fruit of the tomatoes; however, the total yield was reduced. In addition, reduction in the potassium content was accompanied by an increase in the sodium and magnesium content of the leafy vegetables and tomatoes. The increases in sodium and magnesium content occurred to compensate for the decline in potassium content so that the growth of the plant was not inhibited.
For cultivation of cucumber (Cucumis sativus L.) under greenhouse, the “wire-suspended cultivation system with intact growing runners” which requires routine exercises for successive repositioning of growing tips of the runners or secondary vines throughout the cultivation period, is now widely employed by the horticultural growers in Japan. During the growth of young vines of cucumber plants under the forcing-culture conditions, repositioning of vines is frequently required due to the spatial limitation or for the ease of fruit harvesting. As the vines are actively self-fixed on the wires by tendril-based networking, the vine repositioning exercise requires cutting or removal of multiple tendrils without severely damaging the vines or growing tips. The present study documented the tendril tensile resisting against the mechanical vine repositioning exercises. The mean tensile strength for single tendril support was shown to be ca. 6.12 N (1.07 N/mm2 or 1.07 MPa at the base of tendrils). The force required for tendril removal per single vine would be 5.20 N and 15.78 N for exercises performed at 2 day-interval and a week interval, respectively. Based on these figures, we propose here a simplified mechanical procedure for tendril cutting and repositioning of vines, which could be readily automated through the future efforts.