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Agricultural lands are gradually being contaminated by heavy metals (HMs) obtained from urbanization and human activities. Lead (Pb) is one of the major heavy metals easily enters into food cycle and causes different health abnormalities. So elimination of this dangerous heavy metal from surface water is crucial and in this regard phyto-extraction based phytoremediation is an environmentally safe procedure. Again, this removal process can be amplified through the use of plant growth regulators exogenously. With this aim, an experiment was conducted to know the efficiency of the use of indole-3-acetic acid (IAA) on phyto-extraction of Pb by an aquatic hyper-accumulator plant Ipomoea aquatica. The plants were grown hydroponically with 200ppm Pb treated with 200ppm IAA exogenous spray or mixed with Hoagland solution (HS) or both. The control treatment was HS supplemented with Pb. From the experiment, it was observed that control treatment causes a great reduction in growth parameters as the plants suffered from Pb stress. Treatment with Control + IAA (spray+dissolve), produced tallest plants, longest roots and maximum dry weight. On the other hand, these parameters were got declined in case of Pb treated plants (control). Maximum Pb were accumulated on root, stem followed by leaf for Control + IAA (spray+dissolve). Control treatment caused less Pb accumulation on plant parts. So, maximum bioaccumulation factor (BCF) in root, shoot and leaf were 35.87, 15.33 and 9.15 respectively for Control + IAA (spray+dissolve) treatment. In case of root to shoot translocation, the maximum translocation factor (TF) value (0.5118) was found for Control + IAA (spray) than other treatments. Again for shoot to leaf, the maximum TF value (0.6051) was for HS + HM treatment (Control) and minimum TF value (0.4469) was observed for Control + IAA (spray). From the study, it is confirmed that, exogenous indole-3-acetic acid (IAA) successfully assist Pb phyto-extraction from aquatic bodies and Ipomoea aquatica is a potential heavy metal hyper-accumulating plant.

To assess the effects of organic and inorganic N fertilizers regarding wheat yield and growth a field experiment was carried out from November 2019 to March 2020 at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh. There were three replications of the experiment, which was set up using a randomized full block design. The experiment comprises four varieties viz. BARI Gom-28, BARI Gom-30, BARI Gom-31, BARI Gom-32 and five levels of N viz. Control, 90 kg N ha-1 from prilled urea (PU), 57 kg N ha-1 from prilled urea (PU) + 3 t ha-1 poultry manure (PM) as organic N source, 62 kg N ha-1 from PU + 5 t ha-1 cowdung as organic N source, 29 Kg N ha-1 from PU + 4 t ha-1 vermicompost as organic N source. The outcome of the experiment revealed that there were substantial differences in the growth and yield of wheat due to different varietal effects and application of organic and inorganic nitrogen fertilizers, although some of the attributes were not found significant. At growth, BARI Gom-32 produced the highest number of total tillers hill-1 and leaf area index, while the highest number of total tillers hill-1 and leaf area index were obtained from 57 kg N ha-1 from PU and 3 t ha-1 PM at 20, 40, 60 and 80 DAS. At harvest, the highest number of effective tillers plant-1 (2.82), filled grain spike-1 (32.06), 1000-grain weight (61.07 g), grain yield (3.94 t ha-1), straw yield (5.85 t ha-1) and harvest index (40.11%) were obtained from BARI Gom-32. While, application of 57 kg N ha-1 from PU and 3 t ha-1 PM produced the tallest plant (95.49 cm), number of total tillers plant-1 (3.96), number of effective tillers plant-1 (3.20), filled grain spike-1 (36.61), 1000-grain weight (60.18 g from T5), grain yield (4.34 t ha-1), straw yield (6.23 t ha-1) and harvest index (41.07%). Again, the maximum number of total tillers plant-1 (4.06), number of effective tillers plant-1 (3.46), filled grain spike-1 (39.13), 1000-grain weight (64.62 g), grain yield (4.38 t ha-1), straw yield (6.27 t ha-1 ) and harvest index (41.16%) were found from BARI Gom-32 in combination with 57 kg N ha-1 from prilled urea and 3 t ha-1 poultry manure. Therefore, it can be concluded that BARI Gom-32 in combination with 57 kg N ha-1 from prilled urea and 3 t ha-1 poultry manure was more potential in terms of yield and would be suggested for the cultivation of wheat.

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University (BAU), Mymensingh during the period from July to December 2019 to study the effect of cultivar and seedling age on the performance of short duration transplant Aman rice. The experiment comprised four Aman rice cultivars, viz., BRRI dhan49, BRRI dhan56, BRRI dhan66 and BRRI dhan71, and four seedling ages viz. 20, 25, 30 and 35-day old seedlings. The experiment was laid out in a randomized complete block design with three replications. Results of the study showed that growth, yield and yield contributing characters were significantly influenced by cultivars, seedlings age and their interactions. At growth stage, BRRI dhan49 with 20-day old seedlings produced the tallest plant (57.67 cm and 67.33 cm, respectively), the highest number of total tillers hill-1 (15.00 and 13.67, respectively) and total dry matter (8.03 g m-2 and 11.50 g m-2, respectively) at 30 and 50 DAT. At harvest, the highest number of total and effective tillers hill-1 (12.82 and 12.00), longest panicle (24.50 cm), highest number of grains panicle-1 (128.80), heaviest 1000-grain weight (23.17 g), highest grain yield (5.35 t ha-1) and highest harvest index (51.69 %) were obtained from the cultivar BRRI dhan66. While, thirty-day old seedlings produced the highest number of total and effective tillers hill-1 (13.46 and 12.70), longest panicle (24.67 cm), highest number of grains panicle-1 (136.90), highest grain (5.62 t ha-1) and straw yields (5.81 t ha-1) and harvest index (51.67 %). In case of interactions, BRRI dhan66 with 30-day old seedlings produced the highest number of total and effective tillers hill-1 (14.67 and 13.97), longest panicle (26.00 cm), highest number of grains panicle-1 (146.7), highest grain yield (6.31 t ha-1) and highest harvest index (52.72 %). So, result of the present study reveals that BRRI dhan66 with 30-days old seedlings was found to be the best for obtaining maximum grain yield.

The present study was undertaken to observe the effect of combined application of organic manures and inorganic fertilizers on growth, yield and yield contributing characters of black gram. The experiment was laid out in a randomized complete block design (RCBD) with three replications. The experiment comprises eight treatments viz. Control (no application of manures and fertilizer), Recommended doses of fertilizer (RDF), Cowdung @ 5 t ha-1 + 50% of RDF, Poultry manure @ 5 t ha-1 + 50% of RDF, Vermicompost @ 5 t ha-1 + 50% of RDF, Cowdung @ 5 t ha-1 + Poultry manure @ 5 t ha-1 + 50% of RDF, Cowdung @ 5 t ha-1 + Vermicompost @ 5 t ha-1 + 50% of RDF and Poultry manure @ 5 t ha-1 + Vermicompost @ 5 t ha-1 + 50% of RDF. Combined application of organic manures and inorganic fertilizers exerted significance influence on growth, yield and yield contributing characters of black gram. At growth, the tallest plant (38.74 cm), the highest number of leaves plant-1 (15.55), leaf dry weight plant-1 (6.99 g) and stem dry weight plant-1 (3.01 g) of black gram at 50 days after sowing (DAS) were obtained from poultry manure @ 5 t ha-1 and vermicompost @ 5 t ha-1 along with 50% of RDF. While, at 50 DAS, the highest number of nodules plant-1 (55.22) was recorded from cowdung @ 5 t ha-1 along with 50% of RDF and the highest number of SPAD value plant-1 (42.03) was found in poultry manure @ 5 t ha-1 along with 50% of RDF. Again, at maturity, the highest number of seeds pod-1 (5.86), yield plant-1 (7.77 g), grain yield m-2 (130.70 g) and total dry weight plant-1 (17.21 g) were obtained from poultry manure @ 5 t ha-1 and vermicompost @ 5 t ha-1 along with 50% of RDF. Therefore, it can be concluded that poultry manure @ 5 t ha-1 and vermicompost @ 5 t ha-1 along with 50% of RDF combination might be a promising practice for black gram cultivation.

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during July 2017 to December 2017 to study the combined effect of vermicompost with inorganic fertilizers on the growth attributes of aromatic fine rice varieties. The experiment comprised three varieties viz. BRRI dhan34, Binadhan-13 and Kalizira, and five nutrient managements viz. Control (no application of manures and fertilizer), Recommended dose of inorganic fertilizers ( i.e. 150, 95, 70, 60, 12 kg ha-1 of Urea, TSP, MOP, Gypsum and Zinc Sulphate, respectively), vermicompost @ 3 t ha-1, 25% less than recommended dose of inorganic fertilizer + vermicompost @ 1.5 t ha-1, 50 % less than recommended dose of inorganic fertilizer + vermicompost @ 3 t ha-1. The experiment was laid out in a randomized complete block design with three replications. Growth characters of aromatic fine rice were significantly influenced by variety, nutrient management and interaction of variety and nutrient management. In case of variety, the highest number of total tillers hill-1 leaf area index, total dry matter production and chlrophyll content were obtained from Binadhan-13 at all sampling dates. While, Kalizira produced the lowest number of total tillers hill-1, total dry matter, leaf area index and chlorophyll content except plant height at all sampling dates. In case of nutrient management, the tallest plant, the highest number of total tillers hill-1, total dry matter production, leaf area index and chlrophyll content were obtained from 50 % less than recommended dose of inorganic fertilizer + vermicompost @ 3 t ha-1 at all sampling dates. But the shortest plant, the lowest number of total tillers hill-1, leaf area index, total dry matter production, crop growth rate and chlorophyll content were found in control (no manures and fertilizers) at all sampling dates. In case of interaction of variety and nutrient management, the highest number of total tillers hill-1, leaf area index, total dry matter production and chlorophyll content were found in Binadhan-13 along with 50 % less than recommended dose of inorganic fertilizer + vermicompost @ 3 t ha-1 at all sampling dates. So, it can be concluded that Binadhan-13 along with 50% less than the recommended dose of inorganic fertilizers + vermicompost @ 3 t ha-1 combination might be a promising practice for aromatic fine rice cultivation.

K+/Na+ homeostasis is important for land plants, particularly under salt stress. In this study, the structure and ion transport properties of the high-affinity K+ transporter (HKT) of the liverwort Marchantia polymorpha were investigated. Only one HKT gene, MpHKT1, was identified in the genome of M. polymorpha. Phylogenetic analysis of HKT proteins revealed that non-seed plants possess HKTs grouped into a clade independent of the other two clades including HKTs of angiosperms. A distinct long hydrophilic domain was found in the C-terminus of MpHKT1. Complementary DNA (cDNA) of truncated MpHKT1 (t-MpHKT1) encoding the MpHKT_Δ596-812 protein was used to examine the functions of the C-terminal domain. Both MpHKT1 transporters fused with enhanced green fluorescent protein at the N-terminus were localized to the plasma membrane when expressed in rice protoplasts. Two-electrode voltage clamp experiments using Xenopus laevis oocytes indicated that MpHKT1 mediated the transport of monovalent alkali cations with higher selectivity for Na+ and K+, but truncation of the C-terminal domain significantly reduced the transport activity with a decrease in the Na+ permeability. Overexpression of MpHKT1 or t-MpHKT1 in M. polymorpha conferred accumulation of higher Na+ levels and showed higher Na+ uptake rates, compared to those of wild-type plants; however, phenotypes with t-MpHKT1 were consistently weaker than those with MpHKT1. Together, these findings suggest that the hydrophilic C-terminal domain plays a unique role in the regulation of transport activity and ion selectivity of MpHKT1.

Abiotic stresses are the dominant constraints to successful crop production in the modern era. Over the past few decades, researchers have devised various techniques to ease the effects of abiotic stresses on crop plants. Biochar is a vital eco-friendly biostimulant that mostly increases crop production and alleviates the adverse effects of different abiotic stresses. It improves crop yield as a fertiliser and soil quality as a soil conditioner. Biochar amendment in the soil is gaining popularity these days. This is because it improves the physio-biochemical and biological properties of soil. Biochar enhances abiotic stress tolerance as well as growth and yield of plants by modulating ionic homeostasis, photosynthetic apparatus, antioxidant machineries, reducing heavy metal accumulations and oxidative damages. However, the stress-relieving roles of biochar have not been thoroughly assembled. This review summarises current reports of biochar application and discusses the potential roles of biochar amendment in soil for crop growth and production under stress and non-stress conditions. This review also covers the possible mechanisms for how abiotic stress mitigation is accomplished in plants and the limitations and prospects of biochar application in agriculture.

Agriculture farmers face abundant risk for crop cultivation at rural area of Bangladesh. About 85% of population in coastal region of Bangladesh, Dumki upazila, related to agriculture for livelihood directly or indirectly. To mitigate the problem facing by the farmers, there are available a lots of climate smart technologies. However, different demographic, socio-economic, production, management and post-harvest determinants influences the adoption of these modern technologies. This study focuses on the identification of farmer’s socio-economic condition, their knowledge, attitude, and perception on improvement of existing livelihood based on selected personal and demographic variables. Both primary and secondary data has been collected from different sources to fulfill the objectives. The results of this study indicated that the farmer’s age, education level and farming experiences significantly influence the adoption of modern technologies. Farmer’s knowledge, perception and attitude differ on different demographic condition like, age, sex, education, farm size, farming year. Results also showed that lacking of quality seeds, lacking/high price of labor and other inputs for crop production hastens the adoption of modern technologies. This study provides some recommendation which might impacts on betterment of farmers’ occupational condition by establishing proper policy and legislation both in local and national level. Asian J. Med. Biol. Res. 2021, 7 (4), 348-358

Twenty-two rice lines were used to evaluate salt tolerance at the Laboratory of Biotechnology Division of Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh. Four SSR markers viz. AP3206f, RM1287, RM7075, and RM10793 were used to screen the germplasm for salt tolerance. SSR analysis revealed that the number of alleles per locus ranged from 3 to 5 with an average of 4.25 alleles per locus. Polymorphism Information Content (PIC) values ranged from 0.4762 (RM7075) to 0.7524 (AP3206f) with an average of 0.61 per locus. The highest genetic diversity (0.7810) was observed in loci AP3206f, and the lowest genetic diversity (0.5620) was observed in loci RM7075 with a mean diversity of 0.6663. The genotypes with genetic similarity clustered together in the dendrogram based on UPGMA method and we observed seven major clusters where cluster I contained most of the genotypes. Cluster I, II, III, IV, V, VI, and VII contained 6, 1, 2, 4, 4, 4 and 1 genotypes, respectively. These results revealed that marker AP3206f would be best in screening 22 rice genotypes followed by RM1287, RM7075, and RM10793 according to PIC values. These findings can have the potential role for further improvement of salinity tolerance rice genotypes through marker-assisted breeding. Asian J. Med. Biol. Res. 2021, 7 (2), 214-221

5-aminolevulinic acid (ALA) modulates various defense systems in plants and confers abiotic stress tolerance. Enhancement of crop production is a challenge due to numerous abiotic stresses such as, salinity, drought, temperature, heavy metals, and UV. Plants often face one or more abiotic stresses in their life cycle because of the challenging growing environment which results in reduction of growth and yield. Diverse studies have been conducted to discern suitable mitigation strategies to enhance crop production by minimizing abiotic stress. Exogenous application of different plant growth regulators is a well-renowned approach to ameliorate adverse effects of abiotic stresses on crop plants. Among the numerous plant growth regulators, 5-aminolevulinic acid (ALA) is a novel plant growth regulator, also well-known to alleviate the injurious effects of abiotic stresses in plants. ALA enhances abiotic stress tolerance as well as growth and yield by regulating photosynthetic and antioxidant machineries and nutrient uptake in plants. However, the regulatory roles of ALA in plants under different stresses have not been studied and assembled systematically. Also, ALA-mediated abiotic stress tolerance mechanisms have not been fully elucidated yet. Therefore, this review discusses the role of ALA in crop growth enhancement as well as its ameliorative role in abiotic stress mitigation and also discusses the ALA-mediated abiotic stress tolerance mechanisms and its limitation and future promises for sustainable crop production.

A field experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, from November 2015 to March 2016 to evaluate the effect of nitrogen (N) fertilizer on the yield and quality of wheat cv. BARI gom30. The experiment comprised four levels of Nitrogen (N) viz., 0, 50, 100, 150 kg/ha. The experiment was laid out in a randomized complete block design with three replications. The experimental result showed that there were significant differences in grain yield and straw yield due to the application of Nitrogen (N), although some of the yield attributes were not found significant. The highest plant height (96.23 cm), number of total tillers/plant (4.58), number of effective tillers/plant (4.00), spike length (10.16 cm), number of fertile spikelets/spike (48.92), number of grains/panicle (20.11), 1000-grain weight (49.78 g), grain yield (5.25 t/ha) and straw yield (6.30 t/ha) were obtained from 100 kg N/ha. The lowest plant height (84.00cm), number of effective tillers/plant (2.33), grain yield (4.25 t/ha) and straw yield (5.42 t/ha) were observed with the application of 0 kg N/ha. The highest number of sterile spikelets/spike (3.17) was found under control and highest harvest index (46.50%) was obtained from 150 kg N/ha. The overall results of the present study demonstrated that wheat may be grown successfully for obtaining maximum yield with the application of 100 kg N/ha.

The purpose of this experiment is to study the combined effect of frequency of weeding and integrated nutrient management on the growth and yield of transplant aman rice (cv. BRRI dhan49). The experiment consisted of five weeding regimes and four integrated nutrient managements. The experiment was laid out in a randomized complete block design with three replications. The highest grain yield (5.80 t ha-1) was obtained from the interaction between weed free and 25% BRRI RD + 75% N from CD which was followed by the applications of pre-emergence herbicide + one hand weeding at 35 DAT and 25% BRRI RD + 75% N from CD treatment. The lowest grain (3.65 t ha-1) was found from the interaction between no weeding and BRRI recommended chemical fertilizers.The degree of statistical relationship between grain yield and number of effective tillers/hill, grain yield and straw yield of BRRI dhan49 exhibited positive relationship. From the results of the study it can be concluded that the application of 25% BRRI RD + 75% N from CD in weed free condition might be used for obtaining the best performance of BRRI dhan49.

Plants are often exposed to abiotic stresses such as drought, salinity, heat, cold, and heavy metals that induce complex responses, which result in reduced growth as well as crop yield. Phytohormones are well known for their regulatory role in plant growth and development, and they serve as important chemical messengers, allowing plants to function during exposure to various stresses. Seed priming is a physiological technique involving seed hydration and drying to improve metabolic processes prior to germination, thereby increasing the percentage and rate of germination and improving seedling growth and crop yield under normal and various biotic and abiotic stresses. Seed priming allows plants to obtain an enhanced capacity for rapidly and effectively combating different stresses. Thus, seed priming with phytohormones has emerged as an important tool for mitigating the effects of abiotic stress. Therefore, this review discusses the potential role of priming with phytohormones to mitigate the harmful effects of abiotic stresses, possible mechanisms for how mitigation is accomplished, and roles of priming on the enhancement of crop production.

Several recent studies have shown that citric acid/citrate (CA) can confer abiotic stress tolerance to plants. Exogenous CA application leads to improved growth and yield in crop plants under various abiotic stress conditions. Improved physiological outcomes are associated with higher photosynthetic rates, reduced reactive oxygen species, and better osmoregulation. Application of CA also induces antioxidant defense systems, promotes increased chlorophyll content, and affects secondary metabolism to limit plant growth restrictions under stress. In particular, CA has a major impact on relieving heavy metal stress by promoting precipitation, chelation, and sequestration of metal ions. This review summarizes the mechanisms that mediate CA-regulated changes in plants, primarily CA’s involvement in the control of physiological and molecular processes in plants under abiotic stress conditions. We also review genetic engineering strategies for CA-mediated abiotic stress tolerance. Finally, we propose a model to explain how CA’s position in complex metabolic networks involving the biosynthesis of phytohormones, amino acids, signaling molecules, and other secondary metabolites could explain some of its abiotic stress-ameliorating properties. This review summarizes our current understanding of CA-mediated abiotic stress tolerance and highlights areas where additional research is needed.

5-aminolevulinic acid (ALA) modulates various defense systems in plants and confers abiotic stress tolerance. Enhancement of crop production is a challenge due to numerous abiotic stresses such as, salinity, drought, temperature, heavy metals, and UV. Plants often face one or more abiotic stresses in their life cycle because of the challenging growing environment which results in reduction of growth and yield. Diverse studies have been conducted to discern suitable mitigation strategies to enhance crop production by minimizing abiotic stress. Exogenous application of different plant growth regulators is a well-renowned approach to ameliorate adverse effects of abiotic stresses on crop plants. Among the numerous plant growth regulators, 5-aminolevulinic acid (ALA) is a novel plant growth regulator, also well-known to alleviate the injurious effects of abiotic stresses in plants. ALA enhances abiotic stress tolerance as well as growth and yield by regulating photosynthetic and antioxidant machineries and nutrient uptake in plants. However, the regulatory roles of ALA in plants under different stresses have not been studied and assembled systematically. Also, ALA-mediated abiotic stress tolerance mechanisms have not been fully elucidated yet. Therefore, this review discusses the role of ALA in crop growth enhancement as well as its ameliorative role in abiotic stress mitigation and also discusses the ALA-mediated abiotic stress tolerance mechanisms and its limitation and future promises for sustainable crop production.

Some plasma membrane intrinsic protein (PIP) aquaporins can facilitate ion transport. Here we report that one of the 12 barley PIPs (PIP1 and PIP2) tested, HvPIP2;8, facilitated cation transport when expressed in Xenopus laevis oocytes. HvPIP2;8-associated ion currents were detected with Na+ and K+, but not Cs+, Rb+, or Li+, and was inhibited by Ba2+, Ca2+, and Cd2+ and to a lesser extent Mg2+, which also interacted with Ca2+. Currents were reduced in the presence of K+, Cs+, Rb+, or Li+ relative to Na+ alone. Five HvPIP1 isoforms co-expressed with HvPIP2;8 inhibited the ion conductance relative to HvPIP2;8 alone but HvPIP1;3 and HvPIP1;4 with HvPIP2;8 maintained the ion conductance at a lower level. HvPIP2;8 water permeability was similar to that of a C-terminal phosphorylation mimic mutant HvPIP2;8 S285D, but HvPIP2;8 S285D showed a negative linear correlation between water permeability and ion conductance that was modified by a kinase inhibitor treatment. HvPIP2;8 transcript abundance increased in barley shoot tissues following salt treatments in a salt-tolerant cultivar Haruna-Nijo, but not in salt-sensitive I743. There is potential for HvPIP2;8 to be involved in barley salt-stress responses, and HvPIP2;8 could facilitate both water and Na+/K+ transport activity, depending on the phosphorylation status.

A total of 10 NERICA lines (7 mutants along with 3 parents) of advanced generations were used for morphological and molecular characterization. The experiments were conducted in both Aus and Aman season, 2014 under different field conditions at the field of Biotechnology division, BINA, BAU Campus, Mymensingh-2202 following Randomized Complete Block Design (RCBD) with three replications. The genotypes differed significantly for all the traits. The seasonal differences on all the traits except 100-seed weight were also highly significant. The season’s × genotypes interactions were highly significant. The mean value of days to maturity was the lowest in Aman season than Aus season and the mean yield of rice lines was the highest in Aman season than Aus season. The phenotypic co-efficient of variations (PCV) were higher than genotypic co-efficient of variations (GCV) for all the traits studied indicating that they all interacted with the environment to some extent. All the traits studied expressed moderate to high heritability estimates ranging from 53.70 to 99.54%. High heritability along with high genetic advance was noticed for the traits, number of filled grain panicle -1 , number of unfilled grain panicle -1 and plant height. Significant positive correlations were recorded for yield plot -1 with effective tillers hill -1 and panicle length and significant negative correlations were recorded for yield plot -1 with days to maturity and unfilled grains panicle -1 . Plant height, total tillers hill -1 , effective tillers hill -1 , panicle length, filled grains panicle -1 and 100-seed weight showed direct positive effect on yield plot -1 at both genotypic and phenotypic level. Therefore, these characters would be reliable criteria for improving yield. Asian J. Med. Biol. Res. June 2018, 4(2): 207-221

Background The universities of Bangladesh are closed for more than seventeen months due to the covid-19 pandemic. This prolonged detachment has psychological consequences among the students. This study assessed the anxiety level and its determinants among the undergraduate students of Bangladesh, along with constraints faced by them during e-learning. Methods A web-based cross-sectional survey among 206 undergraduate students was conducted using a well-structured questionnaire. Their anxiety level was estimated using Zung's self-rating anxiety scale (SAS) and determinates were identified by employing a Tobit model. The problem confrontation index (PCI) was used to rank the constraints. Results About 82.5% of the undergraduate students in Bangladesh are experiencing mild to extreme anxiety, while 14.08% are experiencing extreme anxiety. Students' gender, father's year of schooling, family size, residential area, academic year, current accommodation, and access to high-speed internet affect their level of anxiety. Learning alone at home, lacking access to learning resources and inaccessibility to other e-learning platforms are the top three constraints students faced during e-learning. Limitations Self-reported data, socio-demographic variables and online survey. Conclusion Covid-19 has been causing anxiety among the students. This study recommends providing better internet services for facilitating e-learning along with access to different e-learning platforms.

In rice, the high-affinity K+ transporter, OsHKT1;3, functions as a Na+-selective transporter. mRNA variants of OsHKT1;3 have been reported previously, but their functions remain unknown. In this study, five OsHKT1;3 variants (V1-V5) were identified from japonica rice (Nipponbare) in addition to OsHKT1;3_FL. Absolute quantification qPCR analyses revealed that the transcript level of OsHKT1;3_FL was significantly higher than other variants in both the roots and shoots. Expression levels of OsHKT1;3_FL, and some variants, increased after 24 h of salt stress. Two electrode voltage clamp experiments in a heterologous expression system using Xenopus laevis oocytes revealed that oocytes expressing OsHKT1;3_FL and all of its variants exhibited smaller Na+ currents. The presented data, together with previous data, provide insights to understanding how OsHKT family members are involved in the mechanisms of ion homeostasis and salt tolerance in rice.

OsHKT1;1 in rice, belongs to the high-affinity K+ Transporter family, has been found to be involved in salt tolerance. OsHKT1;1 in japonica rice (Nipponbare) produces mRNA variants, but their functions remain elusive. In salt tolerant rice, Pokkali, eight OsHKT1;1 variants (V1-V8) were identified in addition to the full-length OsHKT1;1 (FL) cDNA. Absolute quantification by qPCR revealed that accumulation of OsHKT1;1-FL mRNA is minor in contrast to that of OsHKT1;1-V1, -V2, -V4, and -V7 mRNAs, all of which are predominant in shoots, while only V1 and V7 mRNAs are predominant in roots. Two electrode voltage clamp (TEVC) experiments using Xenopus laevis oocytes revealed that oocytes-expressing OsHKT1;1-FL from Pokkali exhibited inward-rectified currents in the presence of 96 mM Na+ as reported previously. Further TEVC analyses indicated that six of eight OsHKT1;1 variants elicited currents in a Na+ or a K+ bath solution. OsHKT1;1-V6 exhibited a similar inward rectification to the FL protein. Contrastingly, however, the rests mediated bidirectional currents in both Na+ and K+ bath solutions. These data suggest possibilities that novel mechanisms regulating the transport activity of OsHKT1;1 might exist, and that OsHKT1;1 variants might also carry out distinct physiological roles either independently or in combination with OsHKT1;1-FL.

Some plasma membrane intrinsic protein (PIP) aquaporins can facilitate ion transport. Here we report that one of the 12 barley PIPs (PIP1 and PIP2) tested, HvPIP2;8, facilitated cation transport when expressed in Xenopus laevis oocytes. HvPIP2;8-associated ion currents were detected with Na+ and K+, but not Cs+, Rb+, or Li+, and was inhibited by Ba2+, Ca2+, and Cd2+ and to a lesser extent Mg2+, which also interacted with Ca2+. Currents were reduced in the presence of K+, Cs+, Rb+, or Li+ relative to Na+ alone. Five HvPIP1 isoforms co-expressed with HvPIP2;8 inhibited the ion conductance relative to HvPIP2;8 alone but HvPIP1;3 and HvPIP1;4 with HvPIP2;8 maintained the ion conductance at a lower level. HvPIP2;8 water permeability was similar to that of a C-terminal phosphorylation mimic mutant HvPIP2;8 S285D, but HvPIP2;8 S285D showed a negative linear correlation between water permeability and ion conductance that was modified by a kinase inhibitor treatment. HvPIP2;8 transcript abundance increased in barley shoot tissues following salt treatments in a salt-tolerant cultivar Haruna-Nijo, but not in salt-sensitive I743. There is potential for HvPIP2;8 to be involved in barley salt-stress responses, and HvPIP2;8 could facilitate both water and Na+/K+ transport activity, depending on the phosphorylation status.

We characterized an Na+ transporter SvHKT1;1 from a halophytic turf grass, Sporobolus virginicus. SvHKT1;1 mediated inward and outward Na+ transport in Xenopus laevis oocytes and did not complement K+ transporter-defective mutant yeast. SvHKT1;1 did not complement athkt1;1 mutant Arabidopsis, suggesting its distinguishable function from other typical HKT1 transporters. The transcript was abundant in the shoots compared with the roots in S. virginicus and was upregulated by severe salt stress (500 mM NaCl), but not by lower stress. SvHKT1;1-expressing Arabidopsis lines showed higher shoot Na+ concentrations and lower salt tolerance than wild type (WT) plants under nonstress and salt stress conditions and showed higher Na+ uptake rate in roots at the early stage of salt treatment. These results suggested that constitutive expression of SvHKT1;1 enhanced Na+ uptake in root epidermal cells, followed by increased Na+ transport to shoots, which led to reduced salt tolerance. However, Na+ concentrations in phloem sap of the SvHKT1;1 lines were higher than those in WT plants under salt stress. Based on this result, together with the induction of the SvHKT1;1 transcription under high salinity stress, it was suggested that SvHKT1;1 plays a role in preventing excess shoot Na+ accumulation in S. virginicus.

OsHKT1;1 in rice, belongs to the high-affinity K+ Transporter family, has been found to be involved in salt tolerance. OsHKT1;1 in japonica rice (Nipponbare) produces mRNA variants, but their functions remain elusive. In salt tolerant rice, Pokkali, eight OsHKT1;1 variants (V1-V8) were identified in addition to the full-length OsHKT1;1 (FL) cDNA. Absolute quantification by qPCR revealed that accumulation of OsHKT1;1-FL mRNA is minor in contrast to that of OsHKT1;1-V1, -V2, -V4, and -V7 mRNAs, all of which are predominant in shoots, while only V1 and V7 mRNAs are predominant in roots. Two electrode voltage clamp (TEVC) experiments using Xenopus laevis oocytes revealed that oocytes-expressing OsHKT1;1-FL from Pokkali exhibited inward-rectified currents in the presence of 96 mM Na+ as reported previously. Further TEVC analyses indicated that six of eight OsHKT1;1 variants elicited currents in a Na+ or a K+ bath solution. OsHKT1;1-V6 exhibited a similar inward rectification to the FL protein. Contrastingly, however, the rests mediated bidirectional currents in both Na+ and K+ bath solutions. These data suggest possibilities that novel mechanisms regulating the transport activity of OsHKT1;1 might exist, and that OsHKT1;1 variants might also carry out distinct physiological roles either independently or in combination with OsHKT1;1-FL.

Large cultivable area lies in the costal saline zone of Bangladesh where rice cultivation is largely affected by the salinity. This problem can be effectively addressed by identifying salt-tolerant landraces using modern biotechnological method. Assessment of genetic diversity of rice (Oryza sativa L.) is an important tool for rice breeding and an essential component in germplasm characterization and conservation. The objective of this study was to assess the genetic diversity among 7 landraces along with 3 released variety of Rice using SSR marker. A total of 31 reproducible polymorphic alleles were identified from the loci with an average of 5.167 alleles per locus (ranges from 4-7). The polymorphism information content (PIC) value is a reflection of allelic diversity and frequency among the varieties. PIC value of each marker was evaluated on the basis of the number of alleles and it varied greatly for all the SSR loci tested. PIC values enumerated from the data obtained from allelic variation from 0.595 (RM8094) to 0.797 (AP3206) with an average of 0.697. The average genetic diversity over all SSR loci for the 10 genotypes was 0.740, ranging from 0.660 to 0.820. Positive correlations were found between gene diversity, PIC value and number of allele. These findings can have the potential role for further improvement of salinity tolerance rice genotypes through marker-assisted breeding. [Fundam Appl Agric 2018; 3(2.000): 460-466]