Expression and Ion Transport Activity of Rice OsHKT1;1 Variants

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

Identification and Characterization of Rice OsHKT1;3 Variants

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.</p

Effect of citric acid (CA) priming and exogenous application on germination and early seedling growth of okra (Abelmoschus esculentus L.) plants under salinity stress condition

Salinity is a significant barrier to the healthy germination of seeds, the development of seedlings and ultimately the yield of crops. Salinity tolerance can be effectively induced through seed priming and exogenous application of various treatment agents. The vegetable crop okra is a healthy and well-liked one worldwide. Literature shows that salt stress negatively disturbs the growth of okra plants. In the present research, we investigated the effects of citric acid (CA) as priming and exogenous agents to alleviate the salinity-inhibited germination and early growth of okra plants. The seeds were pretreated with CA (1 mM and 2 mM) and soaked in distilled water (control) for 60 min. Germinated seeds were grown in hydroponic solution and subjected to salt stress (50 mM and 100 mM NaCl) with three independent replications and same concentrations of CA (1 mM and 2 mM) were exogenously sprayed. Our results showed that, seed priming with 1 mM CA significantly produced the highest percentage of germination (GP), germination index (GI), germination energy (GE), seed vigor index (SVI), radicle length and weight, hypocotyl length and weight, and number of lateral roots while decreased mean germination time of okra seeds while compared to the control treatment. Additionally, the findings demonstrated that salt stress dramatically reduced root and shoot length, plant height, root and shoot fresh weight and dry weight, and relative water content (RWC). Under salt stress, the addition of 1 mM and 2 mM CA significantly increased the RWC, root and shoot length, root and shoot fresh and dry weight, and plant height. These results provide information that CA priming improves germination parameters and exogenous treatments can improve the salt tolerance, and seedling characteristics of okra. Therefore, our results suggest that 1 mM CA can be utilized as a seed priming and exogenous application agent reducing the impacts of salt stress and promoting early seedling development of okra

Seed Priming with Phytohormones: An Effective Approach for the Mitigation of Abiotic Stress

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

Assessing the influence of integrated nutrient management on growth performance of aromatic fine rice

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&nbsp;&nbsp; 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

Growth and yield performance of hybrid rice varieties under varying zinc levels

Zinc deficiency in soil is currently a widespread problem in Bangladesh that significantly reduces the yield of a variety of crops, including rice. Despite the fact that many farmers started applying zinc fertilizer, many are unaware of the right amount and application technique. For this reason, to determine the impact of variety and zinc treatment on the performance of hybrid rice, a field experiment was carried out between November 2019 and May 2020 at the Sher-e-Bangla Agricultural University's experimental field in Sher-e-Bangla Nagar, Dhaka-1207. The experiment consisted of two factors as variety (3 types) viz., V1 – BRRI hybrid dhan2, V2 – BRRI hybrid dhan3 and V3 – BRRI hybrid dhan5 and, Zinc management (4 levels) viz., Zn0 – 0 kg ha-1 (control), Zn1 – 2 kg ha-1, Zn2 – 4 kg ha-1 and Zn3 – 6 kg ha-1. The experiment was laid out in a Randomized Complete Block Design (Factorial) with three replications. Data on different growth and yield parameter of rice were recorded and significant variation was found for different treatments. Regarding varietal performance, the maximum panicle number hill-1 (17.10), panicle length (28.03 cm), grain number panicle-1 (109.45), 1000-grain weight (26.50 g), grain yield ha-1 (6.94 t), straw yield ha-1 (8.58 t), biological yield ha-1 (15.51 t) and harvest index (44.62%) were found from the variety BRRI hybrid dhan5. Considering Zn effect, the maximum panicle number hill-1 (16.33), panicle length (27.14 cm), grain number panicle-1 (108.11), 1000-grain weight (25.38 g), grain yield ha-1 (6.81 t), straw yield ha-1 (8.34 t), biological yield ha-1 (15.15 t) and harvest index (44.88%) were found from 6 kg Zn ha-1. In the case of treatment combination of variety and zinc, the maximum panicle number hill-1 (20.17), panicle length (29.45 cm), number of grains panicle-1 (117.74), 1000-seed weight (27.43 g), grain yield (7.80 t ha-1), straw yield (9.20 t ha-1), biological yield (17.00 t ha-1) and harvest index (45.78%) were found from BRRI hybrid dhan5 along with 6 kg Zn ha-1. Therefore, the hybrid rice variety BRRI hybrid dhan5 with a Zn application of 6 kg ha-1 yielded considerably more grain than the other treatment combinations under evaluation

Growth and yield of short duration Aman rice (Oryza sativa) cultivars as influenced by age of seedlings

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

Arsenic detoxification by phytoremediation

Heavy metals pollution is amongst the commonest form of environmental pollution. These metals have accumulated over time from the smelting and mining activities of man, from poor waste disposal practices and from modernization. Recently the impact of heavy metal pollution of the environment is stirring up serious concerns since the discovery that some edible plants accumulate these metals to a level, toxic to both themselves and to the animals that consumes them. Common features of heavily polluted soil include barrenness, desertification, erosion, and this usually result in developmental stagnation in areas with such pollution. More researches have recently been stepped up in the field of remediating soils polluted with heavy metals. Traditional method includes excavation of the top soil, capping of the soil, stabilization of the polluting heavy metals, soil washing. In recent time, emphases have been drawn to the use of plants that has high metal accumulating and tolerating capacity to remediate metal-contaminated soil. This mini-review highlights the different conventional and recent practices in the control of heavy metal pollution

Assessing the influence of integrated nutrient management on growth and yield of Black gram (Vigna mungo L.)

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

A Survey of Barley PIP Aquaporin Ionic Conductance Reveals Ca2+-Sensitive HvPIP2;8 Na+ and K+ Conductance

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