In the current study, we used four soybean varieties PK-1029, PK-472, NRC-7, and Hardee to examine the effect of exclusion of solar UV radiation on photosynthetic efficiency and to test possible variety-dependent sensitivity to ambient UV (280-400 nm). Plants that were grown under UV exclusion filters had higher chlorophyll a and b, efficiencies of PSII and more active reaction centers indicated that PSII were substantially affected by solar UV radiation. The significant increase in net photosynthesis was linked to increased stomatal conductance and lower intercellular concentration of CO2 in UV-excluded plants. The exclusion of solar UV increased seed mass per plant in all soybean varieties as compared to the control; this indicates that ambient UV exclusions boost photosynthetic efficiency and improve soybean yield. The overall cumulative stress response index of four varieties implies that Hardee and PK-472 were more sensitive whereas NRC-7 and PK-1029 were resistant to ambient UV radiations.

• Keywords
• OJIP transient, PSII efficiency, UV exclusion, chlorophyll fluorescence, photosynthesis, soybean,
• Publication type
• Journal Article MeSH

The study aims to understand the effect of UV exclusion and arbuscular mycorrhizal fungi (AMF) inoculation on the photosynthetic parameters of soybean. The study was conducted in nursery bags and plants were grown under iron mesh covered with UV cut-off filters. The plants grown under the exclusion of UV with AMF inoculation (I) showed higher photosynthetic pigments, carbonic anhydrase activity, reduced internal CO2 concentration, enhanced transpiration rate, and stomatal conductance as well as improved photosynthetic rate over uninoculated plants. Moreover, -UVB+I and -UVAB+I plants exhibited an increased performance index, the activity of the water-splitting complex on the donor side of PSII, and the concentration of active PSII reaction centers per excited cross-section. Overall, UV-excluded and AMF-inoculated plants showed the highest quantum yield of PSII and rate of photosynthesis. Our study will pave the way for future investigation to identify the possible role of UV exclusion and AMF in improving the photosynthetic performance for better yield of soybean.

• Keywords
• UV exclusion, arbuscular mycorrhizal fungi, photosynthesis, photosystem II,
• Publication type
• Journal Article MeSH

In this study, the role of the signalling molecule nitric oxide (NO) in magnetopriming-mediated induction of salinity tolerance in soybean seeds is established. The cross-talk of NO with germination-related hormones gibberellic acid (GA), abscisic acid (ABA) and auxin (IAA) for their ability to reduce the Na+/K+ ratio in the seeds germinating under salinity is highlighted. Salt tolerance index was significantly high for seedlings emerging from magnetoprimed seeds and sodium nitroprusside (SNP, NO-donor) treatment. The NO and superoxide (O2•-) levels were also increased in both of these treatments under non-saline and saline conditions. NO generation through nitrate reductase (NR) and nitric oxide synthase-like (NOS-like) pathways indicated the major contribution of NO from the NR-catalysed reaction. The relative expression of genes involved in the NO biosynthetic pathways reiterated the indulgence of NR in NO in magnetoprimed seeds, as a 3.86-fold increase in expression was observed over unprimed seeds under salinity. A 23.26-fold increase in relative expression of NR genes by the NO donor (SNP) was observed under salinity, while the NR inhibitor (sodium tungstate, ST) caused maximum reduction in expression of NR genes as compared to other inhibitors [L-NAME (N(G)-nitro-L-arginine methyl ester; inhibitor of nitric oxide synthase-like enzyme) and DPI (diphenylene iodonium; NADPH oxidase inhibitor)]. The ratio of ABA/GA and IAA/GA decreased in magnetoprimed and NO donor-treated seeds, suggesting homeostasis amongst hormones during germination under salinity. The magnetoprimed seeds showed low Na+/K+ ratio in all treatments irrespective of NO inhibitors. Altogether, our results indicate that a balance of ABA, GA and IAA is maintained by the signalling molecule NO in magnetoprimed seeds which lowers the Na+/K+ ratio to offset the adverse effects of salinity in soybean seeds.

• Keywords
• germination, growth hormones, magnetopriming, nitric oxide, salt stress, tolerance,
• MeSH
• Nitric Oxide Donors pharmacology   MeSH
• Glycine max * MeSH
• Hormones metabolism   MeSH
• Abscisic Acid metabolism   pharmacology   MeSH
• Nitric Oxide metabolism   MeSH
• Plant Growth Regulators * metabolism   pharmacology   MeSH
• Seeds metabolism   MeSH
• Salt Stress MeSH
• Nitric Oxide Synthase metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Nitric Oxide Donors MeSH
• Hormones MeSH
• Abscisic Acid MeSH
• Nitric Oxide MeSH
• Plant Growth Regulators * MeSH
• Nitric Oxide Synthase MeSH

Magnetopriming has emerged as a promising seed-priming method, improving seed vigor, plant performance and productivity under both normal and stressed conditions. Various recent reports have demonstrated that improved photosynthesis can lead to higher biomass accumulation and overall crop yield. The major focus of the present review is magnetopriming-based, improved growth parameters, which ultimately favor increased photosynthetic performance. The plants originating from magnetoprimed seeds showed increased plant height, leaf area, fresh weight, thick midrib and minor veins. Similarly, chlorophyll and carotenoid contents, efficiency of PSII, quantum yield of electron transport, stomatal conductance, and activities of carbonic anhydrase (CA), Rubisco and PEP-carboxylase enzymes are enhanced with magnetopriming of the seeds. In addition, a higher fluorescence yield at the J-I-P phase in polyphasic chlorophyll a fluorescence (OJIP) transient curves was observed in plants originating from magnetoprimed seeds. Here, we have presented an overview of available studies supporting the magnetopriming-based improvement of various parameters determining the photosynthetic performance of crop plants, which consequently increases crop yield. Additionally, we suggest the need for more in-depth molecular analysis in the future to shed light upon hidden regulatory mechanisms involved in magnetopriming-based, improved photosynthetic performance.

• Keywords
• PSII efficiency, biomass, leaf growth, magnetopriming, photosynthetic enzymes, photosynthetic performance,
• MeSH
• Chlorophyll chemistry   metabolism   MeSH
• Fluorescence MeSH
• Photosynthesis * MeSH
• Plant Leaves metabolism   MeSH
• Magnetic Fields * MeSH
• Plant Proteins metabolism   MeSH
• Plants metabolism   MeSH
• Seeds growth & development   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Chlorophyll MeSH
• Plant Proteins MeSH