Photosynthesis In Soybean Research Articles

Effects of potassium deficiency on photosynthesis and photoprotection mechanisms in soybean (Glycine max (L.) Merr.)

Potassium is an important nutrient element requiring high concentration for photosynthetic metabolism. The potassium deficiency in soil could inhibit soybean (Glycine max (L.) Merr.) photosynthesis and result in yield reduction. Research on the photosynthetic variations of the different tolerant soyben varieties should provide important information for high yield tolerant soybean breeding program. Two representative soybean varieties Tiefeng 40 (tolerance to K+ deficiency) and GD8521 (sensitive to K+ deficiency) were hydroponically grown to measure the photosynthesis, chlorophyll fluorescence parameters and Rubisco activity under different potassium conditions. With the K-deficiency stress time extending, the net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of GD8521 were significantly decreased under K-deficiency condition, whereas the intercellular CO2 concentration (Ci) was significantly increased. As a contrast, the variations of Tiefeng 40 were almost little under K-deficiency condition, which indicated tolerance to K+ deficiency variety could maintain higher efficient photosynthesis. On the 25th d after treatment, the minimal fluorescence (F0) of GD8521 was significantly increased and the maximal fluorescence (Fm), the maximum quantum efficiency of PSII photochemistry (Fv/Fm), actual photochemical efficiency of PSII (ϕPSII), photochemical quenching (qP), and electron transport rate of PSII (ETR) were significantly decreased under K+ deficiency condition. In addition, the Rubisco content of GD8521 was significantly decreased in leaves. It is particularly noteworthy that the chlorophyll fluorescence parameters and Rubisco content of Tiefeng 40 were unaffected under K+ deficiency condition. On the other hand, the non-photochemical quenching (qN) of Tiefeng 40 was significantly increased. The dry matter weight of Tiefeng 40 was little affected under K+ deficiency condition. Results indicated that Tiefeng 40 could avoid or relieve the destruction of PSII caused by exceeded absorbed solar energy under K-deficiency condition and maintain natural photosynthesis and plant growth. It was an essential physiological mechanism for low-K-tolerant soybean under K-deficiency stress.

Diurnal depression in leaf hydraulic conductance at ambient and elevated [CO2] reveals anisohydric water management in field-grown soybean and possible involvement of aquaporins

Diurnal cycles of photosynthesis and water use in field-grown soybean (Glycine max) are tied to light intensity and vapor pressure deficit (VPD). At high mid-day VPD, transpiration rates can lead to a decline in leaf water potential (Ψleaf) if leaf hydraulic conductance (Kleaf) is insufficient to supply water to intercellular airspaces in pace with demand. Kleaf is determined by leaf xylem conductivity to water, as well as extra-xylem pathways that are likely mediated by aquaporin water transport proteins. When transpiration demand exceeds the maximum capacity of Kleaf to supply water, high tension in the water column can cause cavitation in xylem, and these emboli-blocked xylem vessels reduce water transport and thus lower Kleaf. Stomatal conductance typically remains high at mid-day for soybean, suggesting either a mid-day increase in Kleaf or that photosynthesis may be maintained at the cost of leaf water status, indicative of an anisohydric water management strategy in soybean. This study examined diurnal fluctuations in Kleaf and Ψleaf, showing a mid-day depression in Kleaf in a pattern closely reflecting that of Ψleaf, indicating that Kleaf depression is the result of cavitation in leaf xylem. The diurnal depression of Kleaf was not prevented by growth at elevated [CO2], which lowered stomatal conductance. Diurnal transcription patterns of aquaporin genes showed that a total of 34 genes belonging to 4 aquaporin families were expressed in soybean leaves, of which 22 were differentially expressed between at least two time points. These data suggest that mid-day Kleaf depression was driven primarily by cavitation at increasing xylem water tensions, but that aquaporins are also likely involved in diurnal regulation of soybean leaf water status. It is further concluded that because soybean photosynthesis is typically sustained at mid-day, Kleaf even at the depressed level was in excess of that needed to sustain a stomatal conductance sufficient to prevent depression of photosynthesis in soybean.

Drought and UV-B radiation effect on photosynthesis and antioxidant parameters in soybean and maize

Drought and ultraviolet-B (UV-B) radiation are the most adverse factors for plant growth and productivity. The aim of this study was to compare the effects and interaction of drought and UV-B radiation in the seedlings of maize and soybean. The relative leaf water content was the main factor resulting in reduced growth in response to drought. The anthocyanin and phenol levels were increased under UV-B radiation. Drought and UV-B radiation caused great membrane damage, as assessed by lipid peroxidation and osmolyte leakage. Catalase, peroxidase, superoxide dismutase and hydrogen peroxide were observed under both stress conditions. Proline increased primarily in drought-stressed seedlings and may be the drought-induced factor with a protective role in response to UV-B. The total dry matter of both plant species was decreased due to the chlorophyll content and photosynthetic rate decreased under single and combined stress conditions. UV-B radiation had more adverse effects on growth of maize and soybean seedlings than drought by the physiological and biochemical parameters measured.

Growth, photosynthesis and nitrogen metabolism in soybean varieties after exclusion of the UV-B and UV-A/B components of solar radiation

A field experiment was conducted to study the impact of the exclusion of the solar UV components on growth, photosynthesis and nitrogen metabolism in soybean (Glycine max) varieties PK-472, Pusa-24, JS 71-05, JS-335, NRC-7 and Kalitur. The plants were grown in specially designed UV exclusion chambers wrapped with filters to exclude UV-B or UV-A/B and transmitted all UV. Exclusion of UV significantly enhanced the growth of the aerial parts as well as the growth of the below ground parts in all of the six soybean varieties. Nitrate reductase activity (NRA) was significantly reduced, whereas leghemoglobin (Lb) content, total soluble protein, net photosynthesis (Pn) and α-tocopherol content were enhanced after UV exclusion. The exclusion of solar UV-A/B enhanced all parameters to a larger extent than the exclusion of solar UV-B in four of the six varieties of soybean except for NRC-7 and Kalitur. These two varieties responded more to UV-B exclusion compared to UV-A/B exclusion. A significant inverse correlation between the NRA and the number of nodules per plant was observed. The extent of response in all parameters was greater in PK-472 and JS71-05 than that in Kalitur and JS-335 after UV exclusion. The exclusion of UV augmented the growth of nodules, Lb content and α-tocopherol levels and conferred higher rates of Pn to support better growth of nodules. Control plants (+UV-A/B) seemed to fulfill their N demand through the assimilation of NO3− resulting in lower symbiotic nitrogen fixation and higher NR activity.

Photosynthesis of soybean under the action of a photosystem II-inhibiting herbicide

Photosynthesis, the fundamental physiological process of plant responsible for the growth and yield of crops, is strongly affected by environmental stresses. Several methods have been used to study changes in the physiological parameters of plants exposed to stresses. The work aimed to study physiological parameters related to photosynthesis in leaf discs of soybean plants exposed to a photosystem II-inhibiting herbicide. Soybean leaf discs obtained from mature leaves of plants in the vegetative stage immersed in bentazon herbicide solutions at concentrations of 0, 100, 250 or 500 μM were evaluated. In experiment I, the effect of the herbicide on chlorophyll a fluorescence transient was measured using a portable fluorometer. In the second experiment, the effect of the herbicide on modulated chlorophyll a fluorescence and gas exchange were evaluated, with the latter being measured with an infrared gas analyzer. The evaluations of transient and modulated fluorescence provided additional information on the photosynthetic activity of soybean leaf discs exposed to the action of bentazon. For the fluorescence transient analysis, performance indices were the parameters most sensitive to the action of bentazon, showing a decrease of approximately 70 % at a dose of 500 μM. For the modulated fluorescence analysis, the photochemical quenching coefficient, the electron transport rate, the photochemical efficiency of photosystem II and the net assimilation rate, decreased in response to herbicide application, with values that were almost equal to zero at a dose of 500 µM, which are the parameters that showed the greatest sensitivity to bentazon in soybean.

Limitations to soybean photosynthesis at elevated carbon dioxide in free-air enrichment and open top chamber systems

It has been suggested that the stimulation of soybean photosynthesis by elevated CO2 was less in free-air carbon dioxide enrichment (FACE) systems than in open top chambers (OTC), which might explain smaller yield increases at elevated CO2 in FACE systems. However, this has not been tested using the same cultivars grown in the same location. I tested whether soybean photosynthesis at high light and elevated CO2 (ambient+180μmolmol−1) was limited by electron transport (J) in FACE systems but by ribulose-bisphosphate carboxylation capacity (VCmax) in OTC. FACE systems with daytime and continuous CO2 enrichment were also compared. The results indicated that in both cultivars examined, midday photosynthesis at high light was always limited by VCmax, both in the FACE and in the OTC systems. Daytime only CO2 enrichment did not affect photosynthetic parameters or limitations, but did result in significantly smaller yields in both cultivars than continuous elevation. Photosynthesis measured at low photosynthetic photon flux density (PPFD) was not higher at elevated than at ambient CO2, because of an acclimation to elevated CO2 which was only evident at low measurement PPFDs.

Interaction of Carbon Dioxide Enrichment and Soil Moisture on Photosynthesis, Transpiration, and Water Use Efficiency of Soybean

Soybean (Glycine max (L.) Merrill) is one of the most important oil and protein sources in the world. Interactive effect of elevated carbon dioxide (CO2) and soil water availability potentially impact future food security of the world under climate change. A rhizotron growth chamber experiment was conducted to study soil moisture interactions with elevated CO2 on gaseous exchange parameters of soybean under two CO2 concentrations (380 and 800 μmol·mol－1) with three soil moisture levels. Elevated CO2 decreased photosynthetic rate (11.1% and 10.8%), stomatal conductance (40.5% and 36.0%), intercellular CO2 concentration (16.68% and 12.28%), relative intercellular CO2 concentration (17.4% and 11.2%), and transpiration rate (43.6% and 39%) at 42 and 47 DAP. This down-regulation of photosynthesis was probably caused by low leaf nitrogen content and decrease in uptake of nutrients due to decrease in stomatal conductance and transpiration rate. Water use efficiency (WUE) increased under elevated CO2 because increase in total dry weight of plant was greater than that of water use under high CO2 conditions. Plants under normal and high soil moisture levels had significantly higher photosynthetic rate (7% to 16%) favored by optimum soil moisture content and high specific water content of soybean plants. Total dry matter production was significantly high when plants grown under elevated CO2 with normal (74.3% to 137.3%) soil moisture level. Photosynthetic rate was significantly and positively correlated with leaf conductance and intercellular CO2 concentration but WUE was significantly negatively correlated with leaf conductance, intercellular CO2 concentration and transpiration rate. However, the effect of high CO2 on plants depends on availability of nutrients and soil moisture for positive feedback from CO2 enrichment.

Leaf mesophyll K+, H+ and Ca2+ fluxes are involved in drought-induced decrease in photosynthesis and stomatal closure in soybean

Understanding the roles of chemical signals for drought tolerance is important for improving plant water use efficiency. Microelectrode ion flux measurement (MIFE), leaf gas exchange, and stomatal imaging were employed to assess the impact of short-term, PEG-induced and prolonged drought stress on soybean plants. We developed a new method to record steady-state K+, H+ and Ca2+ fluxes from leaf mesophyll of soybean plants grown in a glasshouse over a long time period. Long-term K+, H+ and Ca2+ fluxes under drought condition differed significantly from short-term PEG-induced drought stress. Moreover, the magnitude of changes differed between the ion fluxes and the physiological and growth traits. For instance, in the severe drought treatment, differences in the magnitude of Ca2+ efflux between the drought-stressed plants and the control were greater than the changes in aperture width, guard cell width and leaf temperature. In addition, H+ influx and K+ and Ca2+ efflux of leaf mesophyll were highly significantly (P<0.01) correlated with many physiological traits. In summary, our results suggest that a large K+ efflux, alkalisation of apoplastic pH (H+ influx), and an early response of Ca2+ efflux from leaf mesophyll are likely to serve as chemical signals and significant indicators for levels of drought stress in soybean.

Effects of Ozone Stress on Leaf-Level Photosynthesis in Soybean &lt;i&gt;(Glycine max)&lt;/i&gt;

Glycine max were exposed in nine the open-top chambers to three levels of ozone (O3) concentration (ambient, approximately 45 nL·L-1 and two elevated ozone, 80±10 nL·L-1 and 110±10 nL·L-1) in four different growing stages (branching, flowering, podding and filling). In order to study the effect of different ozone concentration on photosynthesis parameters, the emphasis of this research was on photosynthetic pigment contents, parameters of photosynthetic gas exchange, Hill reaction activity and Ca2+/Mg2+-ATPase activity in soybean leaves. This paper reveals its response process and degree of photosynthesis in soybean leaves under different elevated O3, and it could establish the foundation for the study of plants adaptability mechanism under elevated O3 on the molecular level. The results showed that elevated O3 concentration accelerated peroxidation damage, and plants could not tolerate O3-induced injure, thus reducing photosynthesis by stomatal closure because of O3 exposure in soybean leaves. And O3 stress caused an acceleration of caducity that might be in part responsible for the reduction of photosynthesis.

Intercropping Competition between Apple Trees and Crops in Agroforestry Systems on the Loess Plateau of China

Agroforestry has been widely practiced in the Loess Plateau region of China because of its prominent effects in reducing soil and water losses, improving land-use efficiency and increasing economic returns. However, the agroforestry practices may lead to competition between crops and trees for underground soil moisture and nutrients, and the trees on the canopy layer may also lead to shortage of light for crops. In order to minimize interspecific competition and maximize the benefits of tree-based intercropping systems, we studied photosynthesis, growth and yield of soybean (Glycine max L. Merr.) and peanut (Arachis hypogaea L.) by measuring photosynthetically active radiation, net photosynthetic rate, soil moisture and soil nutrients in a plantation of apple (Malus pumila M.) at a spacing of 4 m × 5 m on the Loess Plateau of China. The results showed that for both intercropping systems in the study region, soil moisture was the primary factor affecting the crop yields followed by light. Deficiency of the soil nutrients also had a significant impact on crop yields. Compared with soybean, peanut was more suitable for intercropping with apple trees to obtain economic benefits in the region. We concluded that apple-soybean and apple-peanut intercropping systems can be practical and beneficial in the region. However, the distance between crops and tree rows should be adjusted to minimize interspecies competition. Agronomic measures such as regular canopy pruning, root barriers, additional irrigation and fertilization also should be applied in the intercropping systems.

High Day‐ or Nighttime Temperature Alters Leaf Assimilation, Reproductive Success, and Phosphatidic Acid of Pollen Grain in Soybean [Glycine max (L.) Merr.

ABSTRACTSoybean [Glycine max (L.) Merr.] is often exposed to high daytime and nighttime temperatures during critical growth stages. Threshold mean daily temperature for photosynthesis, respiration, and reproductive process in soybean is ≥26°C. In future, the magnitude of increase in nighttime temperatures will be greater than in daytime temperatures. The objectives were to determine effects of high daytime or nighttime temperatures on (i) leaf photosynthetic and respiration rates; (ii) pollen germination, pod‐set, and seed weight; and (iii) pollen phospholipids profile. Soybean plants were exposed to high daytime temperature (39/20°C), high nighttime temperatures (30/23°C, 30/26°C, and 30/29°C), or optimum temperature (30/20°C) for 10 d at flowering stage. High daytime temperature (39/20°C) or nighttime temperatures (30/29°C) increased leaf respiration rates and decreased leaf chlorophyll content, photosynthetic rate, photochemical quenching, and electron transport rate compared to optimum temperature. Likewise, high temperature decreased pollen viability and germination. Lower pollen germination at high temperature may be due to decreased levels of saturated phospholipids and phosphatidic acid in pollen grains compared with optimum temperature. Pod‐set and seed weight were decreased by high daytime or nighttime temperature. In conclusion, high daytime (39/20°C) or nighttime (30/29°C) temperature decreased leaf photosynthetic rate and pollen germination, leading to lower pod‐set and seed weight.

Photosynthetic responses of soybean (Glycine max L.) to heat‐induced electrical signalling are predominantly governed by modifications of mesophyll conductance for CO2

In recent years, the effect of heat-induced electrical signalling on plant photosynthetic activity has been demonstrated for many plant species. However, the underlying triggers of the resulting transient inhibition of photosynthesis still remain unknown. To further investigate on this phenomenon, we focused in our present study on soybean (Glycine max L.) on the direct effect of signal transmission in the leaf mesophyll on conductance for CO(2) diffusion in the mesophyll (g(m) ) and detected a drastic decline in g(m) following the electrical signal, whereas the photosynthetic electron transport rate (ETR) was only marginally affected. In accordance with the drop in net photosynthesis (A(N) ), energy dispersive X-ray analysis (EDXA) revealed a shift of K, Mg, O and P on leaf chloroplasts. Control experiments under elevated CO(2) conditions proved the transient reduction of A(N) , ETR, the chloroplast CO(2) concentration (C(c) ) and g(m) to be independent of the external CO(2) regime, whereas the effect of the electrical signal on stomatal conductance for CO(2) (g(s) ) turned out much less distinctive. We therefore conclude that the effect of electrical signalling on photosynthesis in soybean is triggered by its immediate effects on g(m) .

土壌の化学性がダイズの根粒形成・光合成・物質生産に及ぼす影響

土壌の化学性がダイズの根粒形成・光合成・物質生産に及ぼす影響

Mammalian androgen stimulates photosynthesis in drought-stressed soybean

Abstract The aim of the present studies was to assess the possibility of compensating the negative effects of drought stress on gaseous exchange and efficiency of photosystem II in soybean seedlings by application of the androgen — androstenedione. Androstenedione (0.25 mg dm−3) was applied via presowing seed soaking (12 h). Control seeds were untreated with steroid. Plants were cultured in pots. On the 12th day of growth, the plants were watered for the last time. Drought symptoms occurred during the next 10 days. On the 22nd day of growth, leaf gaseous exchange and PSII measurements were taken. Afterwards the plants were watered. Two days later measurements were taken again. Androstenedione improved the intensity of leaf net photosynthesis. The effect of androstenedione was manifested during the rehydration of plants that have undergone a period of drought. An increase in net photosynthesis intensity was accompanied by higher transpiration. Possible mechanisms of androstenedione action — effect on aquaporin functionality and membrane stability — are discussed. The significance of ethanol and DMSO (solvents of steroid) in experiments on the physiological activity of androstenedione is also considered.

Open-top chamber facility to study air pollution impacts in South Africa. Part II: SO2–drought interactions on yield, photosynthesis and symbiotic nitrogen fixation in soybean

South Africa has an extremely energy-intensive economy, resulting in substantial air pollution through its coal-fired power stations. Modelled sulphur dioxide (SO2) concentrations on the central Highveld mostly range between 10 and 50 ppb, exceeding 50 ppb in source areas. Well-watered and drought-stressed soybean (Glycine max) plants were exposed to different SO2 concentrations in open-top chambers to study the physiology of SO2 injury by measuring in parallel growth, biomass accumulation, photosynthetic gas exchange (as a function of internal CO2 concentration and photon flux density), chlorophyll a fluorescence, in vitro Rubisco activity and symbiotic nitrogen fixation. A strong concentration-dependent SO2-induced inhibition was displayed in all variables. After fumigation for only 7 d, photosynthesis was reduced without any accompanying visual injury symptoms, even at the 50 ppb treatment level. Exposure to SO2 also resulted in large decreases in biomass accumulation of both well-watered and drought stressed plants. Seed yield reduction of up to 57% occurred in plants exposed to the highest SO2 concentration and simultaneously subjected to drought stress. Root nodule ureide content was lowered at all treatment levels, but was lowered more in the SO2-treated plants subjected to drought stress. The photosynthetic gas exchange data showed a severe decrease in carboxylation and quantum efficiency pointing at increasing mesophyll limitation. The chlorophyll a fluorescence data, pointing at impaired electron transport and formation of end electron acceptors as well as the in vitro activity of Rubisco, supported the gas exchange data. Inhibition of photosynthesis proved to be the main constraint imposed by SO2. SO2 stress was aggravated by simultaneous drought stress.

Gas Exchange Characters with SO&lt;sub&gt;2&lt;/sub&gt; Fumigation of Different Concentration and Time in Soybean

The low concentration of SO2 in the air can promote stomata opening of plants and improving plant photosynthetic rate, but the gradual accumulation of SO2 on plant leaves can convert the chlorophyll into phaeophytin, which has no photosynthetic activity, and then affect the plant growth and crop production. After Fumigation with SO2 in soybean under several different concentrations (4 µl/l,10 µl/l,20 µl/l,40 µl/l) and time spans(1h,2h,4h) respectively, the photosynthesis and gas exchange characteristics were determined. The experimental data showed: (1) with the increasing of concentration and time for fumigation, SO2 had a great adverse effect on photosynthesis in soybean. Such as the light saturation point of plants decreased, the light compensation point increased, and the maximum net photosynthetic rate reduced significantly (e.g., fumigation with SO2,4-40 µl/l-4 h, Anmax reduced 29.5% to control) compared with the control plants’. (2)After all kinds processing time, low concentration of fumigation (4µl/l) caused larger stomatal conductance than control. However, the other treatments caused smaller gs than control. (3)gs revealed significant positive correlation with transpiration rate(E), each treatment and control shows r ≥0.9,P2. (5)Concentration of chlorophyll was no insignificant differences with the control at different treatments. After fumigation, the range of chlorophyll a / b was 1.39~1.61 and there was no big difference from control (chlorophyll a / b is 1.49), except the treatment of 20µl/l-1h, which had a significant decline in chlorophyll b (chlorophyll a / b is 1.71).Results: (1) SO2 concentration had greater impact on soybean than time of fumigation, and the impact of high concentration in short time on soybean was obviously significant. (2) SO2 fumigation in short time and low concentration can promote stomata open, however SO2 also can damage the photosynthetic activity of chlorophyll. After a long time of fumigation, photosynthetic rate decreased rapidly, even if gs increased.

Accelerating yield potential in soybean: potential targets for biotechnological improvement

Soybean (Glycine max Merr.) is the world's most widely grown legume and provides an important source of protein and oil. Global soybean production and yield per hectare increased steadily over the past century with improved agronomy and development of cultivars suited to a wide range of latitudes. In order to meet the needs of a growing world population without unsustainable expansion of the land area devoted to this crop, yield must increase at a faster rate than at present. Here, the historical basis for the yield gains realized in the past 90 years are examined together with potential metabolic targets for achieving further improvements in yield potential. These targets include improving photosynthetic efficiency, optimizing delivery and utilization of carbon, more efficient nitrogen fixation and altering flower initiation and abortion. Optimization of investment in photosynthetic enzymes, bypassing photorespiratory metabolism, engineering the electron transport chain and engineering a faster recovery from the photoprotected state are different strategies to improve photosynthesis in soybean. These potential improvements in photosynthetic carbon gain will need to be matched by increased carbon and nitrogen transport to developing soybean pods and seeds in order to maximize the benefit. Better understanding of control of carbon and nitrogen transport along with improved knowledge of the regulation of flower initiation and abortion will be needed to optimize sink capacity in soybean. Although few single targets are likely to deliver a quantum leap in yields, biotechnological advances in molecular breeding techniques that allow for alteration of the soybean genome and transcriptome promise significant yield gains.

Effects on both the roots and shoots of soybean during dark chilling determine the nature and extent of photosynthesis inhibition

The relative contribution of low soil and air temperatures towards the overall inhibition of photosynthesis in soybean is still unclear. The mechanisms involved in the dark chilling-induced inhibition of photosynthesis were explored further in a chilling tolerant (Highveld Top) and sensitive (PAN809) soybean genotype in experiments where low soil temperatures were present (whole plant chilling, WPC) or absent (shoot-localised chilling, SC). Initially (after three nights of chilling) both the WPC and SC treatments induced the same symptoms in PAN809. These symptoms could thus be ascribed to chilling stress effects on the shoots. Typical symptoms included reduced CO 2 assimilation capacity, inhibition of photosystem II function and lower chloroplast fructose-1,6-bisphosphatase (cFBPase) and sucrose-phosphate-synthase (SPS) activity. When the nodulated root systems of PAN809 were also exposed to low temperatures (WPC treatment), additional constraints gradually developed, which were not observed in Highveld Top. Novel evidence is provided showing that the response in PAN809 is influenced by whether whole-plant or shoot-localised dark chilling occurs and that cFBPase is specifically targeted resulting in severe inhibition of CO 2 assimilation capacity.

Enhancement of germination, growth, and photosynthesis in soybean by pre‐treatment of seeds with magnetic field

Experiments were conducted to study the effect of static magnetic fields on the seeds of soybean (Glycine max (L.) Merr. var: JS-335) by exposing the seeds to different magnetic field strengths from 0 to 300 mT in steps of 50 mT for 30, 60, and 90 min. Treatment with magnetic fields improved germination-related parameters like water uptake, speed of germination, seedling length, fresh weight, dry weight and vigor indices of soybean seeds under laboratory conditions. Improvement over untreated control was 5-42% for speed of germination, 4-73% for seedling length, 9-53% for fresh weight, 5-16% for dry weight, and 3-88% and 4-27% for vigor indices I and II, respectively. Treatment of 200 mT (60 min) and 150 mT (60 min), which were more effective than others in increasing most of the seedling parameters, were further explored for their effect on plant growth, leaf photosynthetic efficiency, and leaf protein content under field conditions. Among different growth parameters, leaf area, and leaf fresh weight showed maximum enhancement (more than twofold) in 1-month-old plants. Polyphasic chlorophyll a fluorescence (OJIP) transients from magnetically treated plants gave a higher fluorescence yield at the J-I-P phase. The total soluble protein map (SDS-polyacrylamide gel) of leaves showed increased intensities of the bands corresponding to a larger subunit (53 KDa) and smaller subunit (14 KDa) of Rubisco in the treated plants. We report here the beneficial effect of pre-sowing magnetic treatment for improving germination parameters and biomass accumulation in soybean.

Effects of Non-stomatal Components on Photosynthesis in Soybean under Salt Stress

Effects of Non-stomatal Components on Photosynthesis in Soybean under Salt Stress