Improvement of Early Maturing and Climate Resilient Chickpea (Cicer arietinum L.) Cultivars Suitable for Multiple Environments in Bangladesh

Ensuring food security for the rapidly increasing population and changing climatic scenarios are requisites for exploiting the genetic divergence of food crops.A study was undertaken to sort out an early maturing chickpea variety for fitting easily between rice-rice cropping systems in the Eastern Indo-Gangetic Plain of Bangladesh.The trial was comprised of eight elite lines of chickpea and executed at various localities in Bangladesh from 2014–15 to 2017–18.The result explored the chickpea genotype,BARI Chola-11 remained superior to the rest of the elite genotypes for having a short maturity period(100–106 days),and lesser days to 50%flowering(47–55 days).The same genotype was recorded to have robust vegetative and reproductive yield attributes including plant height(49–57 cm),podsplant−1(37–50),and optimum 100 seed weight(19.5–20.6 g).Owing to better yield attributes,BARI Chola-11 resulted in the maximum seed yield(1200–1500 kg ha-1)of chickpea and might be recommended for general adoption in the region for boosting nutritional security status through improved productivity under changing climate.

Yield and Pest Performance of High-Temperature Tolerant Tomato (Lycopersicon esculentum) Lines for Year-Round Tomato Production in Bangladesh

The study was conducted at Olericulture Division, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh during summer season of 2021 to see the performances of yield and yield-related components of twelve heat tolerant tomato hybrids. Significant variation was expressed for days to first harvest (101.0 - 108.0 days), while maximum number of fruits per plant was calculated in F1 2101 and F1 2201 (9.5), followed by F1 203, F1 2001, F1 2303, F1 2401 (9.0). The highest single fruit weight was estimated in F1 2501 (195.5 g), followed by F1 2101 (119.0 g), F1 2201 (113.8 g), while the range was 33.1 - 195.5 g. The range of fruit yield was 7.9 - 38.7 t/ha, while higher-yielding hybrids were viz., F1 203 (27.7 t/ha), F1 2101 (35.5 t/ha), F1 2201 (33.9 t/ha) and F1 2501 (28.7 t/ha). Maximum TSS was produced by F1 2501 (5.9%), followed by BARI Hybrid Tomato-8 (5.1%), F1 1101, F1 1903 (5.0%), with a range of 4.0% - 5.9%, while TYLCV infection and leaf sucking pest infestation varied from 0.0% - 10.0% and 3.3% - 16.7%, respectively. Thus, based on the performances of different yield and yield contributing traits, the hybrids, viz., F1 2101, F1 2201, F1 2501 may be selected to develop heat tolerant tomato hybrid varieties for the farmers of sub-tropical regions.

Advances in DNA methylation and its role in cytoplasmic male sterility in higher plants

The impact of epigenetic modifications like DNA methylation on plant phenotypes has expanded the possibilities for crop development.DNA methylation plays a part in the regulation of both the chromatin structure and gene expression,and the enzyme involved,DNA methyltransferase,executes the methylation process within the plant genome.By regulating crucial biological pathways,epigenetic changes actively contribute to the creation of the phenotype.Therefore,epigenome editing may assist in overcoming some of the drawbacks of genome editing,which can have minor off-target consequences and merely facilitate the loss of a gene’s function.These drawbacks include gene knockout,which can have such off-target effects.This review provides examples of several molecular characteristics of DNA methylation,as well as some plant physiological processes that are impacted by these epigenetic changes in the plants.We also discuss how DNA alterations might be used to improve crops and meet the demands of sustainable and environmentally-friendly farming.

Biological Control of Insect Pests of Agricultural Crops through Habitat Management Was Discussed

Biological control through habitat management leads to sustainable insect pest control. Different types of land composition such as multiple landscapes, patchiness of landscapes enhance the natural enemies which ultimately lead to control of insect pest. Plant characteristics such as flower shape, flower color and blooming period ensures excess food for natural enemies like nectar and pollen. Moreover, some agricultural practices such as tillage, crop rotation, and intercropping influence the natural enemies especially parasitoid and preda-tors. Consequently, they increase longevity and fecundity of parasitoid and predator that help to control insect pest. One of the most important recently used methods is push-pull which consists of semiochemicals called Herbi-vore-Induced Plant Volatiles (HIPVs). This compound has been used to pre-vent pest and attract natural enemies.

Composting Constraints and Prospects in Bangladesh: A Review

Composting is a suitable environment-friendly technique to modify organic waste to organic fertilizers and works as soil conditioners by regulating different biological processes. The main objective of a sustainable agricultural production system can be achieved by using quality compost and thereby improving soil health and increased crop yield. This desktop research summarizes the role of composting for sustainable agricultural development with their prospective role, opportunities, and challenges in the context of Bangladesh. Some attention is also given to the composting process and compost industries in Bangladesh. Benefits and constraints regarding the use of compost for achieving sustainable agricultural production systems are also discussed.

Simulating Nitrogen and Irrigation Effects on Wheat Production in Bangladesh under Changing Climate

Climate change impacts are visible in Bangladesh which requires adoption of judicious crop management practices for sustainable agriculture. Crop simulation models are effective in this regard and can be used for optimizing water and nitrogen inputs for maximization of wheat yields. Two field studies were conducted at Bangladesh Agricultural Research Institute (BARI) for evaluating the effect of increased temperature on wheat production under variable water and N rates, through the use of DSSAT v4.6 model. Thirty years historic weather data and BARI Gom-26 wheat-cultivar coefficients, as generated through use of GLUE of DSSAT model, were used for evaluating the impact of temperature rise with variable rates of irrigation water and nitrogen. The effects of four levels of nitrogen (0, 40, 80 and 120 kg ha-1) and four irrigation levels [0 (no irrigation), 1, 2 and 3] on wheat yield were evaluated under 0°C, 1°C, 2°C and 3°C rise in temperature. Simulation results indicated that wheat yield increased with increase in nitrogen application rate, but decreased with the temperature rise. Crop growing duration was reduced by about five days for each degree rise in temperature, irrespective of levels of irrigation water and nitrogen-rates. In general, there was yield reduction of 8.13, 16.77 and 24.97 % with increased temperature of 1°C, 2°C and 3°C, respectively, when compared with no temperature rise treatment. For interaction of temperature rise-N dose, the magnitude of yield decline under temperature rise was higher with increased dose of N. Agronomic N use efficiency at different N rates and temperature rise level were calculated. N use efficiency decreases with the increase in temperature rise and the highest (29.95 kg grain kg-1 N) was obtained from 40 kg N ha-1 treated plot with 0°C temperature rise i.e. existing atmospheric temperature. Simulation results indicated increase in wheat yield with higher levels of irrigation water, and interaction of irrigation level with temperature rise was significant. Irrigation use efficiency decreases with the increase in temperature rise. From the present study, it was seen that the interaction of temperature rise with varying levels of N and irrigation water was significant, and there is a need to design the appropriate inputs’ management, as the adaptation strategy, to sustain the wheat yield under climate change situation.

Calibration and Validation of Decision Support System for Agro-Technology Transfer Model for Simulating Growth and Yield of Maize in Bangladesh

Maize is an emerging important crop in Bangladesh because of its high yield potential and economic profitability compared to rice and wheat crops. There is a need to understand the growth and yield behavior of this crop in varying production environments of Bangladesh. Crop model such as Decision Support System For Agro-technology Transfer (DSSAT) version 4.6 (DSSAT hereafter) can be utilized cost effectively to study the performances of maize under different production environments. It needs to calibrate and validate DSSAT model for commonly cultivated maize cultivars in Bangladesh and subsequently take the model to various applications, including inputs and agronomic management options and climate change that impacts analyses. So, the present study was undertaken to firstly calibrate DSSAT model for popular four hybrid maize cultivars (BARI Hybrid Maize-7, BARI Hybrid Maize-9, Pioneer 30B07 and NK-40). Subsequently, it proceeded with the validation with independent field data sets for evaluating their growth performances. The genetic coefficients for these cultivars were evaluated by using Genotype coefficient calculator (GENCALC) and Generalized likelihood uncertainty estimation (GLUE) module of DSSAT on the basis of first season experiment. The performance of the model was satisfactory and within the significant limits. After calibration, the model was tested for its performance through validation procedure by using second season data. The model performed satisfactorily through phenology, biomass, leaf area index (LAI) and grain yield. Phenology, as estimated through days to flower initiation and maturity, was in good agreement, although simulated results were slightly over predicted compared to observed values but within the statistical significance limit...when compared with observed values at specific growth stages of the crop. The final yield values (10.12 to 10.59 t·ha-1) were in close agreement with the observed values (10.16 to 10.94 t·ha-1), as the percentage error was within tolerable limit (0.39% to 6.81%). The model has been successfully calibrated and validated for Gazipur environment and now can be used for climate change impact studies for similar environments in Bangladesh.

Effect of Elevated Air Temperature and Carbon Dioxide Levels on Dry Season Irrigated Rice Productivity in Bangladesh

Agricultural productivity is affected by air temperature and CO2 concentration. The relationships among grain yields of dry season irrigated rice (Boro) varieties (BRRI dhan28, BRRI dhan29 and BRRI dhan58) with increased temperatures and CO2 concentrations were investigated for futuristic crop management in six regions of Bangladesh using CERES-Rice model (DSSATv4.6). Maximum and minimum temperature increase rates considered were 0°C, +1°C, +2°C, +3°C and +4°C and CO2 concentrations were ambient (380), 421, 538, 670 and 936 ppm. At ambient temperature and CO2 concentration, attainable grain yields varied from 6506 to 8076 kg·ha-1 depending on rice varieties. In general, grain yield reduction would be the highest (13% - 23%) if temperature rises by 4°C and growth duration reduction would be 23 - 33 days. Grain yield reductions with 1°C, 2°C and 3°C rise in temperature are likely to be compensated by increased CO2 levels of 421, 538 and 670 ppm, respectively. In future, the highest reduction in grain yield and growth duration would be in cooler region and the least in warmer saline region of the country. Appropriate adaptive techniques like shifting in planting dates, water and nitrogen fertilizer management would be needed to overcome climate change impacts on rice production.

Effect of Different Mulch Paper on Growth and Yield of Different High Value Vegetables in Bangladesh

The study was undertaken to identify the suitable mulch paper for different high-value vegetables during the winter season of November 2019 to March 2020 at the Olericulture research field of Bangladesh Agricultural Research Institute, Gazipur, Bangladesh. The study was a randomized complete block design with 3 replications. Four vegetable varieties viz., tomato, brinjal, capsicum and broccoli and 3 mulch treatments viz., T1 = Silver over black mulch;T2 = Black mulch;T3 = No mulch were included in this study. Different vegetables responded differently with the changes of mulches irrespective of different characters. it was clear that fruit number, average fruit weight, fruit length, fruit diameter were strongly related to soil moisture content. The effect of different plastic mulches on fruit weight per plant and yield (t/ha) was significant. Mulching produced higher fruit yield per plant and fruit yield per hectare than for the control, indicating that the mulch had a positive effect in generating increased fruit yield. Silver over black plastic mulch produced the highest fruit yield viz., 98.05 t/ha (tomato), 54.11 t/ha (brinjal), 34.33 t/ha (capsicum), 26.09 t/ha (broccoli) followed by black and no mulches, while the control plot produced the lowest fruit yield.

Socio-Ecological Vulnerabilities and Major Cereal Crops Production in Bangladesh

Bangladesh enjoys food self-sufficiency or deficiency depending on crop damages by drought, floods, cyclones, storm/tidal surges and other natural hazards. Data on climate extremes were collected from literatures. Landsat images were analyzed for water availability. Arithmetic, geometric and weighted means were calculated for community vulnerability delineation using IDRISI3.2. About 12.64% populations live in disaster prone areas and their sensitivity to exposed hazards depends on financial capabilities. Crop area damages by natural hazards were the highest in Dhaka division followed by Rajshahi division during 2009-2014. The highest economic loss ($613 million) was found in Barisal division followed by Dhaka ($198.7 million) division. Flooding was the most damaging climate extreme followed by drought and hailstorm. Rice crops are frequently exposed to climate extremes and caused economic loss of $228 million during 2009-2014. Economic losses were <$110 to 1,000 ha-1 because of wheat/maize areas damaged by natural hazards. The most vulnerable areas are situated in the south-west and north-west part of the country. The most affected areas (35.4% of the country) had economic losses of $940-1,170 ha-1. About 2-4.7 million households (HH) were affected by different natural hazards in different regions of the country. Flood affected HHs were predominant in northern and north-east regions of the country. Common adaptations to natural hazard exposures are crop switching and migration. The other adaptation options could be improvement of post disaster recovery efficiency through financial support, supplying seeds and other inputs based on seasonal suitability.

Morphological, Pathological, Biochemical and Molecular Characterization of <i>Ralstonia solanacearum</i>Isolates in Bangladesh

One thirty samples (fifty-five potato tubers, twenty-seven potato stems, three chili stems, twenty-eight soil samples, five weed samples, three banana leaves, and nine water samples) were examined and one hundred six (106) Bangladeshi isolates of Ralstonia solanacearum were isolated and identified. Isolation was made on selective media (Tetrazolium chloride media) and R. solanacearum was identified based on morphological, pathological and biochemical properties and polymerase chain reaction (PCR) by using the species-specific primers. Studies showed that 81.54% (106) samples were positive on tetrazolium chloride solid medium. Among them 90 isolates were virulent and rest of them were avirulent. Fifty isolates were selected for chemical characterization based on hypersensitivity test. R. solanacearum is gram negative, aerobic facultative bacteria on the basis of chemical characterization. Fifty tested isolates expressed as race 3 while in biovar test forty-eight showed as biovar III and the rest two showed as biovar I. In nine tested isolates from the three districts a species-specific band of 280 bp was amplified in PCR that confirmed the identity of R. solanacerum.

Yield and Yield Contributing Performance of 75 Tomato Germplasm in Bangladesh

The study was conducted with 75 tomato germplasm/lines at the farm of Olericulture Division, Horticulture Research Centre (HRC), Bangladesh Agricultural Research Institute, Gazipur, Bangladesh during the winter season of 2020-21 to evaluate the WorldVeg tomato germplasm. The days to first harvest were varied from 106 to 116 days while twelve lines were harvested within 106 - 108 days. The number of fruits per plant varied from 11.7 to 71.3, while the range of single fruit weight was 16.4 - 186.6 g. Fruit yield per hectare was 15.7 - 150.4 t/ha where the highest fruit yield per hectare was obtained from the lines AVTO 1702 (150.40 t/ha), followed by AVTO 1409 (126.54 t/ha), AVTO 1010 (120.60 t/ha), AVTO 1712 (111.33 t/ha), AVTO 1711 (107.23 t/ha). The range of fruit length was observed 2.07 to 6.8 cm, while the fruit diameter was 1.9 to 7.4 cm. The range of pericarp thickness was 0.14 to 0.8 cm, while the range of number of locule was 2.0 to 8.2. The range of TSS level was 2.0% - 8.2%, while the shelf life of the tomato lines was recorded 5.2 to 10.3 days. Considering earliness, quantitative and qualitative characters, eleven WorldVeg Center tomato lines AVTO 1010, AVTO 1315, AVTO 1409, AVTO 1711, AVTO 1712, AVTO 1713, AVTO 1717, AVTO 1907, AVTO 1911, AVTO 1915 and AVTO 1921 were found promising. So, these eleven lines can be selected for further confirmation.

Isolation and Characterization of Beneficial Microorganisms in Organic, Semi-Organic and Conventional Fertilizer Treated Agricultural Field Soil and Comparison of Bacterial Richness

The effect of different farming systems on microbial communities in agricultural environment was investigated in the present study. Depending on the present farming trend, the microbial distribution in agricultural soils treated with organic, semi-organic and conventional fertilizers was analyzed. A total of 20 soil samples were collected from different types of agricultural fields of Bangladesh Agricultural Research Institute (BARI, Gazipur). Microorganisms playing beneficial roles in soil such as nitrogen fixation (e.g. Rhizobium sp., Azotobacter sp.), phosphate solubilization (e.g. Bacillus sp., Pseudomonas sp., Phosphobacteria) and auxin production (e.g. Pseudomonas sp., Serratia sp. and Bacillus sp.) were evaluated from each of the samples. The results revealed that agricultural fields treated with chemical fertilizers showed lower microbial count than that of organic fertilizer treated agricultural fields’ soil samples. In addition, organic fertilizers amended field soils have higher phytohormone (Auxin) activities, phosphate solubilization bacteria and other bacterial richness compared to chemical fertilizer applied field soil.

Determination of Organochlorine and Synthetic Pyrethroid Pesticide Residues in Water Samples Collected from Different Locations of Bangladesh

The present study was aimed to validate an analytical method for the quantification of 19 organochlorine and 2 synthetic pyrethroid pesticide residues in water samples using modified quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction and Gas Chromatography coupled with Electron Capture Detector (ECD). The selected pesticide residues were determined by in-house validated method. The analytical method was validated by evaluating the accuracy, precision, linearity, limit of detection (LOD) and limit of quantification (LOQ). The average recoveries of the selected pesticides ranged from 78% to 117% with RSDr ≤ 12% in two fortification levels of 0.02 and 0.1 mg/L. The linearity was ≥0.995 for all of the selected pesticides. The LOD ranged from 0.003 to 0.006 mg/L and the LOQ was 0.02 mg/L for all the selected analytes. This method was applied satisfactorily for the residue analysis of 108 water samples collected from nine districts of Bangladesh. Among the analyzed samples, only 4 had cypermethrin residues (0.026 mg/L, 0.034 mg/L, 0.045 mg/L and 0.05 mg/L). The level of detected cypermethrin residues were above the WHO recommended guide line values of water quality.

Potato tonoplast sugar transporter 1 controls tuber sugar accumulation during postharvest cold storage

Cold-induced sweetening(CIS),the undesirable sugar accumulation in cold-stored potato(Solanum tuberosum L.)tubers,is a severe postharvest issue in the potato processing industry.Although the process of sucrose hydrolysis by vacuolar invertase during potato CIS is well understood,there is limited knowledge about the transportation of sucrose from the cytosol to the vacuole during postharvest cold storage.Here,we report that among the three potato tonoplast sugar transporters(TSTs),StTST1 exhibits the highest expression in tubers during postharvest cold storage.Subcellular localization analysis demonstrates that StTST1 is a tonoplast-localized protein.StTST1 knockdown decreases reducing sugar accumulation in tubers during low-temperature storage.Compared to wild-type,potato chips produced from StTST1-silenced tubers displayed significantly lower acrylamide levels and lighter color after cold storage.Transcriptome analysis manifests that suppression of StTST1 promotes starch synthesis and inhibits starch degradation in cold-stored tubers.We further establish that the increased sucrose content in the StTST1-silenced tubers might cause a decrease in the ABA content,thereby inhibiting the ABA-signaling pathway.We demonstrate that the down-regulation ofβ-amylase StBAM1 in StTST1-silenced tubers might be directly controlled by ABA-responsive element-binding proteins(AREBs).Altogether,we have shown that StTST1 plays a critical role in sugar accumulation and starchmetabolism regulation during postharvest cold storage.Thus,our findings provide a newstrategy to improve the frying quality of cold-stored tubers and reduce the acrylamide content in potato chips.

Molecular characterization of sweet potato(Ipomoea batatas[L.]Lam)germplasms for desirable traits by using simple sequence repeats markers

Every breeding program that aims to create new and improved cultivars with desired traits mostly relies on information related to genetic diversity.Therefore,molecular characterization of germplasms is important to obtain target cultivars with desirable traits.Sweet potato[Ipomoea batatas(L.)Lam]is widely considered the world’s most important crop,with great diversity in morphological and phenotypic traits.The genetic diversity of 20 sweet potato germplasms originating from Bangladesh,CIP,Philippines,Taiwan,and Malaysia were compared,which was accomplished by genetic diversity analysis by exploring 20 microsatellite DNA markers for germplasm characterization and utilization.This information was effective in differentiating or clustering the sweet potato genotypes.A total of 64 alleles were generated using the 20 primers throughout the 20 germplasm samples,with locus IBS97 having the highest number of alleles(5),whereas locus IbU33 had the fewest alleles(2).The alleles varied in size from 105(IbU31)to 213 base pairs(IBS34).The Polymorphism Information Content(PIC)values for the loci IbL46 and IBS97 varied from 0.445 to 0.730.IBS97 has the highest number of effective alleles(3.704),compared to an average of 2.520.The average Shannon’s diversity index(H)was 1.003,ranging from 0.673 in IbU3 to 1.432 in IBS97.The value of gene flow(Nm)varied between 0.000 and 0.005,with an average of 0.003,whereas genetic differentiation(FST-values)ranged between 0.901 and 1.000.The sweet potato germplasm included in this study had a broad genetic base.SP1 vs.SP9 and SP12 vs.SP18 germplasm pairings had the greatest genetic distance(GD=0.965),while SP1 vs.SP2 germplasm couples had the least genetic diversity(GD=0.093).Twenty genotypes were classified into two groups in the UPGMA dendrogram,with 16 genotypes classified as group“A”and the remaining four genotypes,SP10,SP18,SP19,and SP20,classified as group“B.”According to cluster analysis,the anticipated heterozygosity(gene diversity)of Nei(1973)was 0.591 on average.In summary,SSR markers successfully evaluated the genetic relationships among the sweet potato accessions used and generated a high level of polymorphism.The results of the present study will be useful for the management of germplasm,improvement of the current breeding strategies,and the release of new cultivars as varieties.

Salicylic Acid Application Mitigates Oxidative Damage and Improves the Growth Performance of Barley under Drought Stress

Drought is a severe environmental constraint,causing a significant reduction in crop productivity across the world.Salicylic acid(SA)is an important plant growth regulator that helps plants cope with the adverse effects induced by various abiotic stresses.The current study investigated the potential effects of SA on drought tolerance efficacy in two barley(Hordeum vulgare)genotypes,namely BARI barley 5 and BARI barley 7.Ten-day-old barley seedlings were exposed to drought stress by maintaining 7.5%soil moisture content in the absence or presence of 0.5,1.0 and 1.5 mM SA.Drought exposure led to severe damage to both genotypes,as indicated by phenotypic aberrations and reduction of dry biomass.On the other hand,the application of SA to drought-stressed plants protected both barley genotypes from the adverse effects of drought,which was reflected in the improvement of phenotypes and biomass production.SA supplementation improved relative water content and proline levels in drought-stressed barley genotypes,indicating the osmotic adjustment functions of SA under water-deficit conditions.Drought stress induced the accumulation of reactive oxygen species(ROS),such as hydrogen peroxide(H2O2)and superoxide(O_(2)•^(−)),and the lipid peroxidation product malondialdehyde(MDA)in the leaves of barley plants.Exogenous supply of SA reduced oxidative damage by restricting the accumulation of ROS through the stimulation of the activities of key antioxidant enzymes,including superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),ascorbate peroxidase(APX)and glutathione peroxidase(GPX).Among the three-applied concentrations of SA,0.5 mM SA exhibited better mitigating effects against drought stress considering the phenotypic performance and biochemical data.Furthermore,BARI barley 5 showed better performance under drought stress than BARI barley 7 in the presence of SA application.Collectively,our results suggest that SA played a crucial role in improving water status and antioxidant defense strategy to protect barley plants from the deleterious effects of water deficiency.

Nutritional Composition and Bioactive Compounds of Bael (Aegle marmelos) and Development of Functional Food Products

Aegle marmelos, widely known as bael, belongs to the Rutaceae family. It is one of the most inexpensive and appealing fruits, considered to be an essential source of natural antioxidants and bioactive components. The major purpose of the research study was to investigate the nutritional composition and bioactive constituents of bael pulp, as well as to develop new value-added products that maintain the maximum quantity of nutrients. The developed food products were subjected to evaluate sensory attributes according to a nine-point hedonic scale. It was found that the moisture, protein, fat, crude fiber, and total ash content of bael fruit pulp were 61.20%, 2.48%, 0.47%, 3.04%, and 1.29%, respectively. When compared to the catechin standard, the antioxidant activity of such extract indicated good antioxidant capacity, with an IC50 value of 75.68 μg/ml for methanol extract. Vitamin C content was about 10.21 mg/100g. Besides, total flavonoid and phenolic contents were found as 140 mg of Quercetin Equivalent (QE)/g and 106.65 mg of Gallic Acid Equivalent (GAE)/g, respectively. Results of sensory attributes revealed that there was a significant difference (P ba and bael bar. The overall acceptability of bael murabba (6.7) and bael bar (7.1) is acceptable in quality, but their specific characteristics were found slightly different by the test panelists. These products might be applicable for the treatment of several diseases like atherosclerosis, diabetes, constipation, irritable bowel syndrome, peptic ulcer, tumor, and osteoporosis.