BARI Soybean Research Articles

Dry matter distribution, yield and seed quality of soybean (Glycine max) genotypes as affected by water stress

Water stress is a major constraint for crop productivity and culturing right cultivars may produce a considerable yield under such stressful condition. An experiment was conducted inside a vinyl house to evaluate the effect of water stress on dry matter distribution, yield, and seed quality of eight soybean genotypes, viz. G00006, BD2336, AGS383, PK472, BCS-1, NCS-1, BU Soybean-1 and BARI Soybean-6. They were grown in pots and subjected to water stress (20% of field capacity, FC) and control (80% of FC). The water stress reduced plant height, leaf number, leaf, stem, and root dry matter by 23, 45, 46, 45 and 19%, respectively, across the genotypes. Under water stress, the soybean genotypes G00006, BCS-1, NCS-1 and BARI Soybean-6 beard only 6 to 30% pod and 5 to 34% seed compared to the control condition. The results further indicated that yield of BD2336 and AGS383 were less affected by the stress than those of other genotypes. Interestingly, water stress exerted positive effect on seed germination, viability, speed of germination and vigor index in BD2336 and AGS383, respectively. Nitrogen and seed protein content were found the highest in BCS-1 under control (9.82 and 58.42% respectively) followed by AGS383. Phosphorus content in seed also reduced by the stress in the tested genotypes, except BD2336 (0.29% in control and 0.96% in water stress) and BARI Soybean-6. Potassium content in seed was reduced by the stress in the tested genotypes, except G00006 and BARI Soybean-6. Based on the findings related to water stress effects on yield and seed quality, particularly seed protein of the tested eight soybean genotypes, it was concluded that genotypes AGS383 and BD2336 might be considered for field trial under water deficit condition.

SOYBEAN GERMPLASM SHOWS VARIATION IN FARMERS PARTICIPATORY TRIAL IN THE COASTAL REGION OF BANGLADESH

The cultivation of soybean is still concentrated in the coastal region of greater Noakhali District of Bangladesh, where salinity hinders crop production. There is no suitable salt tolerant variety so far. At Bangabandhu Sheikh Mujibur Rahman Agricultural University, 170 soybean genotypes were screened and finally three,namely AGS313 (BU soybean-3), G00028 (BU soybean-4), and BD2330 were found fairly salt tolerant at 5 and 10 dSm-1 salinity. In Rabi 2022-23 season the selected three genotypes, G00056 as a high yielding promising genotype, and three varieties namely BU soybean-2, BARI soybean-6 and Binasoybean-2, i.e. altogether seven genotypes were grown in 700 decimals land, both saline and non-saline soils, of 12 farmers in different upazillasof Noakhali, Laksmipur and Bhola districts. The seeds were sown by the last week of January’ 23. Salinity of the fields at harvestwas found 5- 13 dSm-1, thoughinitially varied from 0 – 4 dSm-1. Yield contributing characters were measured appropriately. Standard error was used for showing the mean differences. Farmers’ discussion on the performance of the genotypes were held from time to time. Salinity decreasedplant height, maturityduration, number of pods plant-1, 1000-seed weight and grain yield ha-1. However, AGS313 and G00028 were affected less than other genotypes. Under non-saline and low saline conditions relatively higher yield was found in BU soybean2 (2657 kg ha-1 in Bhola, 3397 kgha-1 in Subornachar), G00056 (2341 in Laksmipur sadar, 3390 kg ha-1 in Subornachar), AGS313 (2612 in Ramgoti, 3266 kg ha-1 in Subornachar) and G00028 (2464 in Bhola sadar, 3374 kg ha-1 in Subornachar) compared to other genotypes. The lowest yield was found in BARI soybean6 (1715 kg ha-1 in Ramgoti) followed by Binaoybean-2 (1868 kg ha-1 in Laksmipur sadar). However, under saline field conditions (5- 8 dSm-1) G00028 (866 kg ha-1 in Komolnagar, 1374 kg/ha in Subornachar) and AGS313 (860 kg ha-1in Ramgoti, 1333 kg ha-1 in Subornachar) produced substantially higher yield than other genotypes/ varieties. The lowest yield was obtained from G00056 (170 kg ha-1) from Komolnagar. Based on the results of multi-location trials, and discussions with the farmers the genotypes AGS313 and G00028 were registered as BU soybean-3and BU soybean-4, respectively as relatively salt tolerant varieties from the National Seed Board.

Effect of phosphorus fertilization on nodulation, growth, yield and quality of soybean varieties

Phosphorus is a very important nutritional element that affects soybean growth and nodule nitrogen fixation. The objective of the study was to assess the effect of phosphorus on the growth, yield and quality of different soybean varieties. In this regard, five different doses of phosphorus viz., control (no phosphorus), 50% of the recommended dose (RD) (18 kg ha-1), 100% of RD (36 kg ha-1), 150% of RD (54 kg ha-1) and 200% of RD (72 kg ha-1) were applied on eight distinct soybean varieties namely Shohag, BARI Soybean-5, BARI Soybean-6, PB-1, Binasoybean-1, Binasoybean-2, Binasoybean-3 and Binasoybean-4. The experiment was set up using a randomized complete block design with three replications, Soybean varieties showed variability in terms of plant stature, number of branches plant-1 and number of nodules plant-1. Application of 100% of RD of phosphorus gave maximum plant height, number of branches plant-1 and nodules plant-1 at 45, 60 and 75 DATs. In the case of variety, Binasoybean-1 showed the maximum number of pods plant-1, 100-seed weight, and seed yield. Application of 100% RD of phosphorus exhibited maximum number of branches plant-1, pod length, pods plant-1, seeds pod-1, seed yield, protein and oil contents. Considering the interaction effect, Binasoybean-1 responded well to the application of 100% of RD of phosphorus and gave the maximum seed yield with the highest protein content. Finally, it may be concluded that Binasoybean-1 with the application of 100% RD of phosphorus would be recommended to get desirable yield and quality of soybean.

EFFECT OF BRADYRHIZOBIUM INOCULUM AND LEVELS OF PHOSPHORUS ON THE YIELD AND QUALITY OF SOYBEAN

<p class="Default"><strong>Background:</strong> Soybean is one of the major oil seed crops in Bangladesh. Combine application of <em>Rhizobium</em> inoculation and phosphorus fertilizer could be an important factor to get maximum yield and quality of soybean. <strong>Objective: </strong>To evaluate the effect of Bradyrhizobium inoculum and levels of phosphorus on yield and quality of soybean varieties. <strong>Methodology</strong>: The experiment evaluated three factors namely, varieties, Bradyrhizobium inoculum and phosphorus levels. The three varieties were: i) Binasoybean-1 ii) Binasoybean-2 and iii) BARI Soybean-6. Bradyrhizobium inoculum levels were: i) control (no inoculum), ii) 50% of recommended dose (RD) (25 g kg<sup>-1</sup> seed) iii) 100% of RD (50 g kg<sup>-1</sup> seed). The phosphorus levels were: i) control (no phosphorus) ii) 50% of RD (18 kg ha<sup>-1</sup>), iii) 100% of RD (36 kg ha<sup>-1</sup>). The experiment was laid out in a randomized complete block design with three replications. Data were recorded on yield, yield contributing characters and quality parameters of seeds. <strong>Results:</strong> Binasoybean-1 performed superiorly in terms of all the yield and yield contributing characters. Application of 100% of RD of Bradyrhizobium inoculum and application of 100% of RD of phosphorus also showed superior performance. Considering the interaction effect, the findings of the study indicate that Binasoybean-1 responded well to the application of 100% of RD of phosphorus and 100% of RD of Bradyrhizobium and gave maximum seed yield. The highest protein content (39.21%) was found in Binasoybean-2, 50% of RD of phosphorus with no Bradyrhizobium inoculum and the highest oil content was found (19.33%) in Binasoybean-2, no phosphorus and 50% of RD of Bradyrhizobium inoculum. <strong>Implication:</strong> Binasoybean-1 with the application of 100% of RD of phosphorus and 100% of RD of Bradyrhizobium might be recommended to obtain higher yield soybean in Bangladesh. <strong>Conclusion:</strong> From this study it may be concluded that recommended dose of phosphorus and Bradyrhizobium is beneficial for a higher yield of Binasoybean-1.</p>

Effect of Rhizobium inoculum on the Growth, Yield and Quality of Soybean

Rhizobium inoculation can increase soybean yield, but its performance is influenced by soybean genotypes. The objective of the study was to assess the effect of Rhizobium inoculum on the growth, yield and quality of soybean varieties. In this regard, five different rates of Rhizobium inoculum were applied on eight distinct soybean varieties namely Shohag, BARI Soybean-5, BARI Soybean-6, PB-1, Binasoybean-1, Binasoybean-2, Binasoybean-3 and Binasoybean-4. The experiment was set up using a randomized complete block design with three replications. Soybean varieties showed variability in terms of plant stature, number of branches plant-1 and number of nodules plant-1 at different days after sowing. Among the varieties, Binasoybean-4 produced the tallest plant at 45 and 60 DAS and at 60 DAS variety PB-1 produced the tallest plant. At 45 DAS Binasoybean-2, at 60 DAS BARI Soybean-6 and at 75 DAS Binasoybean-4 produced the highest number of branches plant-1. In case of nodule production, Binasoybean-3 produced the highest number of nodules palnt-1 at 45, 60 and 75 DAS. Inoculation of seeds with 100% of RD of Rhizobium gave maximum plant height, number of branches plant-1 and nodules plant-1. It is noticed that Binasoybean-4 with the application of 100% of RD of Rhizobium inoculum produced the tallest plant and number of branches plant-1 at 45 DAS but at 60 DAS, though the tallest plant was found in the variety Binasoybean-4 with 100% of RD of Rhizobium inoculum but it was statistically identical to Binasoybean-3 with 100% of RD of Rhizobium inoculum. Binasoybean-4 with 100% of RD of Rhizobium inoculum also gave maximum number of branches plant-1 at 75 DAS. But Binasoybena-3 with 100% of RD of Rhizobium inoculum produced the highest number of nodules plant-1 at 60 DAS. In case of variety Binasoybean-1 performed superiorly in terms of all the yield and yield contributing characters. Application of 100% of RD of Rhizobium inoculum also showed superior performance. The highest seed yield (2.92 t ha-1) was recorded in Binasoybean-3 with the application of 100% of RD Rhizobium inoculum. The highest protein content was also documented in this treatment combination. Finally, it may conclude that Binasoybean-3 with the application of 100% of RD Rhizobium inoculum might be recommended for maximizing seed yield and to get best quality soybean.

EFFECT OF IRRIGATION FREQUENCY ON GROWTH AND YIELD OF SOYBEAN

A field experiment was conducted at the research field of HSTU, Dinajpur during November 2019 to March 2020 to find out the effect of irrigation frequency on the growth and yield of Soybean (Glycine max L.) cv. BARI Soybean-6. The experiment was carried out with a RCBD with four replications of irrigation treatments viz, I0= no irrigation (control), I1= one time at 20 days after sowing (DAS), I2= two times (20 and 40 DAS), I3= three times (20, 40, and 60 DAS). At 105 DAS the highest plant height (52.53 cm) was found from I2 treatment and the shortest plant (45.82 cm) from I0 treatment. The highest (5.91) leaf area index was obtained from the treatment of three irrigation (I3) at 90 DAS and the lowest (5.1) leaf area index from the control (I0). At the 90 DAS highest nodule number (9.208) and the lowest nodule number was (6.459) recorded from I3 and I0, respectively. The highest (90.09 g) fresh weight was obtained from the treatment I2 at 90 DAS and the lowest (65.64 g) was recorded in I0. I3 produced the highest amount of dry matter of (29.50 g) and the lowest amount of dry matter production at harvest (20.67 g) in I0 treatment. The highest seed yield was observed from I2 (1.638 t ha-1 ) which was statistically similar with I3 whereas, the lowest obtained from I0 (1.075 t ha-1 ). The highest small stover yield was obtained from I3 (1.759 t ha-1 ) which is statistically similar to I2 (1.754 t ha-1 ) whereas the lowest was observed from I0 (1.540 t ha-1 ) which was statistically similar to I1 (1.566 t ha-1 ). The highest biological yield was found from I2 (3.425 t ha-1 ) which is statistically similar to I3 and the lowest was obtained from I0 (2.56 t ha-1 ). The maximum harvest index was found from I2 (47.71 %) and the minimum was obtained from I0 (40.81 %). I2 treatment showed more significant results than the other treatment I0, I1 and I3. So, two times irrigation showed significant effect showed the highest yield of 1.638 t ha-1.

Morpho-Physiological Responses of Soybean Varieties to Salinity Stress

Soybean (Glycine max L. Merr) has a tremendous value in agriculture as a good source of high-quality plant protein and vegetable oils in one hand and nitrogen fixing ability on the other, now a day largely growing in coastal salt marshes areas of Bangladesh. The aim of this study was to evaluate morphological and physiological responses of soybean varieties (Shohag, BARI Soybean-6, BARI Soybean-5 and Binasoybean-4) to pot grown plants in different concentrations of salinity level i.e., control (0.3), 4, 8 and 12 dS m−1 during 2020-21. Irrespective of the variety, with the increase of salinity levels physiological parameters as well as seed yield were greatly affected. Salinity stress decreased total chlorophyll (Chl a+b) and total dry matter (TDM) was reduced due to salinity stress, which ultimately reduced seed yield irrespective of the variety. Sodium (Na+), calcium (Ca2+), potassium (K+) ion content and the potassium sodium ratios (K+: Na+) in leaf tissue were significantly affected by salinity levels. Under salinity stress, BARI Soybean- 6 showed a higher K+: Na+ ratio in leaf, which indicates higher tolerance to salinity compared to others. However, H2O2 and MDA contents was comparatively lower in the respective variety. This variety also showed higher TDM production, filled pods plant-1 and seed yield plant-1 in all salinity levels compared to other varieties. Results revealed that, soybean var. BARI Soybean-6showedmore tolerance against salinity stress compared to other varieties.
 Bangladesh Agron. J. 2022, 25(1): 15-22

Response of Yield and Quality of Soybean (cv. BARI Soybean-6) to Phosphorus and Sulphur Fertilization under Old Brahmaputra Floodplain Soil of Bangladesh

Background: Soybean is a potential oil seed crop in Bangladesh due to its heavy consumption throughout the country. The lower yield of soybean in Bangladesh compared to the world context might be due to non-judicious fertilization especially phosphorus (P) and sulphur (S). Hence, the study was undertaken to find out the influence of P and S on yield and quality of soybean. Methods: An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Bangladesh. The study comprised four levels of phosphorus viz. 0, 20, 40 and 60 kg P ha-1 and four levels of sulphur 0, 15, 30 and 45 kg S ha-1. The experiment was laid out in a factorial randomized completed block design with three replications. Result: The highest number of branches plant-1, pods plant-1, 100-seed weight, seed yield, harvest index, protein and oil content were found in 60 kg P along with 30 kg S ha-1 while the lowest seed yield, protein and oil content were found in control. Therefore, application of 60 kg P with 30 kg S appeared as the promising practice for obtaining higher seed yield and better quality of BARI Soybean-6.

Effect of different weeding regimes on growth, nodulation, and yield performance of Soybean cv. Barisoybean-6

The experiment was conducted at Agricultural field laboratory in Noakhali Science and Technology University during the period from mid-January 2019 to 1st week of May 2019, to find out the growth, nodulation, and yield performance of soybean cv. BARI soybean 6 under different weeding regimes. The experiment consists of four treatments viz. T0 (No weeding), T1 (Weed free), T2 (Two hand weeding at 15 DAS and 30 DAS) and T3 (Three hand weeding at 15 DAS, 30 DAS and 45 DAS). The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Characters like plant height, number of pod plant-1, number of effective pod plant-1, number of non-effective pod plant-1, number of seed pod-1 and yield varied significantly among the different weeding regimes. The highest seed yield (1.275- ton ha-1) was recorded at T1 (weed free) and the lowest seed yield (0.903-ton ha-1) was observed at T0 (No weeding) condition. The economic analysis of the treatments showed that farmers will be better off by adopting two weeding regimes and weeding at 15 DAS and 30 DAS is therefore recommended for high income.
 Res. Agric., Livest. Fish.8(2): 193-199, August 2021

On-Farm Adaptation of Some Oilseed Crops Under Acidic Soil of Sylhet Region in Bangladesh

Screening of improve varieties for new areas is necessary to address the soil and environment for improving crop production systems. In this context, six separate field trials were conducted at farmer’s field in Sylhet areas for the two consecutive crop seasons during 2017-18 and 2018-19, respectively to evaluate the performance of improved varieties of crops with the existing cultivars. Each experiment was laid out in randomized complete block design with six dispersed replications. The unit plot size was varied with experiments. The result showed that improved varieties of oilseed crops mustard var. BARI Sarisha-16, soybean var. BARI Soybean-6, groundnut var. BARI Chinabadam-9, sesame var. BARI Til-4 and sunflower var. BARI Surjomukhi-2 performed better under the soil and climatic conditions of Sylhet region. This result reveled that these varieties of oilseed crops could be suitable for higher productivity and economic return.
 Bangladesh Agron. J. 2020, 23(2): 87-95

Growth, Flower Dropping, Pod Set and Yield Response of Soybean Varieties as Affected by Suplemental Fertilizer Spray at Flowering

A field experiment was conducted during the period from January to May 2014 to study the response of growth, flower dropping, pod setting and yield of two soybean varieties to foliar fertilization of urea at early stage of flowering. Soybean varieties, BARI Soybean-5 and BARI Soybean-6, were feeded with four supplemental foliar spray treatments of fertilizer, viz. M1: Control i.e., no additional nutrient spray; M2: 20% of recommended urea spray at flowering; M3: 20% dose of the recommended MoP; and M4: 20% dose of the recommended DAP at early flowering stage. The experiment was laid out in a split-plot design with three replications. There was no significant effect of variety, fertilization spray or their interaction observed on growth parameters. However, flower and pod dropping was affected with higher flower dropping (55.2%) in BARI Soybean-5 and maximum pod dropping (16.44%) with DAP spray treatment. Higher yield attributes’ values such as seeds pod-1 (2.42), seed yield (1.18 t ha-1), stover yield (1.02 t ha-1), and biological yield (2.21 t ha-1) were obtained with foliar DAP spray treatment. The interaction of BARI Soybean-5 and foliar DAP spray showed the highest seed yield (1.48 t ha-1), stover yield (1.26 t ha-1) and biological yield (2.75 t ha-1).
 Bangladesh Agron. J. 2020, 23(2): 111-117

Fertilizer Management for Maximizing Soybean (Glycine max L.) Production in Saline Agro- Ecosystem of Barguna

An experiment was conducted at saline agro-ecosystem of Burir Char Union, Barguna District during January to June 2018, with a view to find out the fertilizer management for maximizing soybean (Glycine max L.) production in saline agro-ecosystem was laid out in randomized complete block design consisted of three varieties of soybean and four levels of fertilizer doses with three replications. Three varieties of soybean viz. BARI Soybean-5, BARI Soybean-6 and Binasoybean-3 and four fertilizer levels viz. T1 = 25-30-45-10-1.0-1.0 kgha-1 N-P-K-S-Zn-B (Soil test based fertilizer); T2 = 30-40-60-12-2.0-1.0 kgha-1 N-P-K-S-Zn-B (Fertilizer recommendation guide, 2012); T3 = 40-20-15-0-0-0 kgha-1 N-P-K-S-Zn-B (Farmers practices); T4 = Control native fertility were considered which placed in a factorial randomized block design. The variety had significant influence on plant height, branches plant-1, number of filled pods plant-1, number of unfilled pods plant-1, seed yield plant-1, seed yield (t ha-1), stover yield (t ha-1). BARI Soybean-6 performed better than the other two varieties. The fertilizer doses had significant influence on plant height, branches plant-1, number of filled pods plant-1, number of unfilled pods plant-1, seed yield plant-1, 100-seed weight, seed yield (t ha-1), stover yield (t ha-1). Fertilizer doses 25-30-45-10-1.0-1.0 kgha-1 N-P-K-S-Zn-B (Soil test based fertilizer) gave the maximum yield. The interaction between variety and fertilizer doses V2T1 (BARI Soybean-6 and 25-30-45-10-1.0-1.0 kgha-1 N-P-K-S-Zn-B) produced the maximum yield SO, the variety BARI Soybean-6 with fertilizer dose 25-30-45-10-1.0-1.0 kgha-1 N-P-K-S-Zn-B could be suitable combination for higher yield of soybean in saline agro ecosystem of Barguna.
 Bangladesh Agron. J. 2019, 22(1): 89-93

Mitigation of Salinity Stress in Soybean Using Organic Amendments

A pot experiment was carried out in semi-controlled condition at the Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur from November 2015 to March 2016 to assess the effect of organic amendments to mitigate salinity stress in Soybean var. BARI soybean 5. Two types of organic amendments i) water hyacinth compost and ii) rice husk biochar were mixed in soil @ 5 and 10 t ha-1 of both. Saline solution was prepared by adding tap water in seawater to make 5 and 10 dS m-1 salinity respectively. Plants were irrigated with the salt solution from 14th day after sowing (DAS) to maturity and the control plants were irrigated with tap water. Data on different parameters like plant height, leaf, stem, root dry matter and yield contributing parameters were recorded at harvest. Experimental results revealed that salinity decreased plant height, dry weight of leaf, stem and root as well as yield of soybean plant-1. Application of water hyacinth compost and rice husk biochar had positive effects on mitigating the negative effects of salinity stress on all those parameters studied. However, rice husk biochar at the rate of 5 t ha-1 showed best result to mitigate salinity stress at low salinity (5 dSmdS m-1 condition.
 Bangladesh Agron. J. 2018, 21(1): 39-50

Influence of Inorganic and Organic Fertilizers on Growth and Yield of Soybean

The experiment was executed at the Agronomy researchfield of Sher-e-Bangla Agricultural University, Dhaka-1207, during the period from November, 2015 to March, 2016 to study the effects of fertilizer management of different combinations of inorganic and organic fertilizers on growth, yield attributes and yield of soybean (var. BARI Soybean 6). The treatment combinations wereT0= Control, T1= fertilization at recommended fertilizer dose (RFD - urea 50 kg ha-1, TSP 150 kg ha-1, MoP 100 kgha-1, gypsum 80 kg ha-1 and boron 500 kg ha-1), T2= Bio-fertilizer + 50% RFD, T3= Biofertilizer + 75% RFD, T4= Mixed fertilizer + 50% RFD, T5= Mixed fertilizer + 75% RFD, T6= Vermi-compost + 50% RFD, T7= Vermicompost + 75% RFD, T8= Poultry litter + 50% RFD and T9= Poultry litter + 75% RFD. Results indicated that application of fertilizer at recommended dose, vermi-compost + 75% RFD and poultry litter + 75% RFD produced higher grain yield 2053, 2073 and 2166 kg ha-1, respectively over control. It was also observed thatconsidering the sustainable yield and environment friendly,poultry litter + 75% RFD (T9) and vermi-compost + 75% RFD (T7) couldbe promising for soybean cultivation.
 Bangladesh Agron. J. 2018, 21(1): 77-81

Chlorophyll content, water relation traits and mineral ions accumulation in soybean as influenced by organic amendments under salinity stress

The pot experiment was conducted to assess the effect of organic amendments to improve leaf chlorophyll and water content as well as mineral ions accumulation in BARI soybean 5 under saline condition. Two types of organic amendments i. water hyacinth compost ii. rice husk biochar were mixed in soil at 5 tha-1 and 10 tha-1 of both. Irrigation was done with 50 and 100 mM saline solution from 14th days after sowing (DAS) to maturity, where control plants were irrigated with tap water. Data on chlorophyll content, exudation rate, relative water content (RWC), water retention capacity (WRC) in leaf were measured at flowering stage as well as Na, K, Ca, Mg and Na: K ratio in leaf and stem were also recorded at harvest. Results revealed that salinity decreased chlorophyll content, exudation rate, relative water content, water retention capacity and K, Ca, Mg content in leaf and stem of soybean plant. Water hyacinth compost and rice husk biochar had positive effects to mitigate negative effects of salinity on soybean plant. However, rice husk biochar at 5 tha-1 showed best result to mitigate salinity stress on soybean at low salinity (50 mM) condition.

Effect of drought stress on water relation traits of four soybean genotypes

An experiment was conducted in a venyl house at the environmental stress site of Bangabandhu Sheikh Mujibur Rahman Agricultural University during September to December 2012 to know the internal water status under drought stress in soybean genotypes, viz. Shohag, BARI Soybean-6, BD2331 (relatively stress tolerant) and BGM2026 (susceptible). Drought (water) stress reduced the leaf water potential in all the genotypes though was more negative in tolerant genotypes than in susceptible ones. The lowest leaf water potential was obtained from BARI Soybean-6 (-1.58 MPa) and the highest in BGM2026 (-1.2 MPa). Relative water content (RWC) decreased remarkably in all the genotypes and reduction was more in susceptible than tolerant genotypes. At 8.00 am, RWC of stressed plants decreased by 9.58, 9.02, 8.90 and 13.90% in the genotype Shohag,, BARI Soybean-6, BD2331 and BGM2026 at vegetative stage, respectively. Drought stress decreased the exudation rate in all the genotypes of soybean and it was 24, 27, 22 and 12 mg h-1 in the genotype Shohag, BARI Soybean-6, BD2331 and BGM2026 at vegetative stage, respectively. Leaf temperatures in drought stressed plant were higher than in well-watered plants. Shohag, BARI Soybean-6, BD2331 and BGM2026 showed 4.7, 4.5 5.2 and 11.07% increase in leaf temperature due to water stress. At drought stressed treatment reduction in leaf water potential, relative water content, exudation rate and water retention capacity were noticed at the three growth stages in all the genotypes with a concurrent increase in leaf temperature. Genotypes BARI Soybean-6, Shohag and BD2331 showed considerably less reduction in relative water content, exudation rate and water retention capacity, high reduction in leaf water potential and less increase in leaf temperature during drought were considered as drought tolerant. However genotype BGM2026 showed considerably high reduction in relative water content, exudation rate and water retention capacity, low reduction in leaf water potential and high increase in leaf temperature was considered as drought susceptible.SAARC J. Agri., 15(2): 163-175 (2017)

Effect of salt and water stress on gas exchange, dry matter production and K+/NA+ ions selectivity in soybean

The experiment was conducted in a vinylhouse at the Banghabandhu Sheikh Mujibur Rahman Agricultural University, Bangladesh during January to May, 2012 to evaluate the effect of salt and water stress on gas exchange characters, dry matter production and K+/Na+ ions selectivity in three selected soybean genotypes, namely Galarsum, BD 2331 and BARI Soybean-6. The genotypes were exposed to six treatments viz. (i) control (tap water), (ii) water shortage (irrigation with 70% depletion of available soil water when leaf began to wilt at 10:00 am), (iii) 50 mM NaCl irrigation, (iv) 50 mM NaCl irrigation + water shortage, (v) 75 mM NaCl irrigation, and (vi) 75 mM NaCl irrigation + water shortage conditions. The results revealed that 75 mM NaCl salt + water stress treatment drastically reduced stomatal conductance, photosynthesis and transpiration rate irrespective of soybean genotypes. However, the genotype Galarsum showed minimum transpiritional water loss (1.45 mmol H2O m-2 s-1) and maximum photosynthesis (20.45 μmol CO2 m-2 s-1) as compared to BD 2331 and BARI Soybean-6 under 75 mM NaCl salt + water stress condition. Combined salt and water stress caused greater inhibition of shoot growth than either of the two in soybean. The shoot dry weights were decreased to 24.58, 23.00 and 21.57% of the control in Galarsum, BD 2331 and BARI Soybean-6, respectively at 75 mM NaCl salt + water stress. The genotype Galarsum accumulated higher amount of K+ (1.19%) and lower amount of Na+ ( 0.11%) in leaf tissue under 75 mM NaCl salt + water stress. Results indicated that the genotype Galarsum was more capable to cope with the high levels of salt under water stress condition than the other two genotypes.Bangladesh J. Agril. Res. 42(3): 487-501, September 2017

Effect of drought stress on bio-chemical change and cell membrane stability of soybean genotypes

An experiment was conducted in a venylhouse at the environmental stress site of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during September to December 2012 to study the effect of drought stress on proline content, soluble sugar content, chlorophyll content and cell membrane stability of soybean genotypes. Four studied genotypes viz., Shohag, BARI Soybean-6 and BD2331 (relatively stress tolerant) and BGM2026 (susceptible) were tested against two water regimes such as water stress and non-stress. Results indicated that due to drought stress there was an increase in proline content and soluble sugar content and decrease in chlorophyll a content, chlorophyll b content, total chlorophyll content, chlorophyll a/b ratio and cell membrane stability. Proline and soluble sugar showed more content in tolerant genotype than in susceptible ones. Chlorophyll reduction was most significant and cell membrane stability was found minimal in susceptible genotypes. From the result, genotype BGM2026 which recorded the lowest proline, soluble sugar content and highest chlorophyll reduction and cell membrane injury was considered as drought susceptible. The variety/genotype of soybean such as BARI Soybean-6, Shohag and BD2331 were more drought stress tolerant and better mechanisms of drought tolerance.Bangladesh J. Agril. Res. 42(3): 475-485, September 2017

Screening of soybean (Glycine max L.) genotypes under water stress condition

Fifty soybean genotypes were screened for their water stress tolerance in a vinylhouse of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during January to May, 2011. The objective of this study was to screen for drought tolerant soybean genotype(s) for improving yield of soybean under rainfed condition in Bangladesh. Water stress was imposed throughout the growing period by withholding irrigation until appearance of wilting symptom. Water stress caused an overall reduction in seed yield of soybean. However, reduction in seed yield due to water stress varied among the soybean genotypes. Variations were measured by tolerance indices, ranking and cluster analysis. Considering stress tolerance indices, ranking and cluster analysis, the genotypes BARI Soybean 5, BARI Soybean 6, Shohag and BD2331 were found as tolerant to water stress.Bangladesh J. Agril. Res. 41(3): 441-450, September 2016

Midday Drop of Relative Leaf Water Content to Drought Tolerance in Soybean

An experiment was conducted in a Venylhouse of Bangabandhu Sheikh Mujibur Rahman Agricultural University during September to December 2012 to determine the effect of midday drop of relative water content (RWC) on drought tolerance of soybean genotypes. Four soybean genotypes viz. Shohag, BARI Soybean-6, BD2331 and BGM2026 were used in the study. Plants were grown in pots under stress and control condition. A marked difference in RWC between morning and midday was observed both in stressed and control plants. BARI Soybean-6 showed higher RWC than rest of the genotypes and BGM2026 showed the lowest at all growth stages. The reduced RWC of BARI Soybean-6 under water stress at vegetative, flowering and pod developing stages were 11.35, 13.52 and 15.04% at 1.00 PM as compared to control, respectively. The reduced RWC of BGM2026 at vegetative, flowering and pod developing stages were 18.99, 20.64 and 23.05% at 1.00 PM, respectively. In stressed plants, midday drop of relative water content was minimal in BARI Soybean-6 (8.97%) and maximum in BGM2026 (17.89%) at 1.00 PM. Under water stress condition BARI Soybean-6 gave the highest seed yield (5.23 g plant-1) and BGM2026 the lowest (3.21 g plant-1) which might be attributed to the drastic reduction in 100-seed weight of RWC in the variety BGM2026 due to the significant reduction in RWC in this variety. Considering the midday drop of RWC and seed yield, it may be concluded that BGM2026 is susceptible and BARI Soybean-6 is drought tolerant among the genotypes.Bangladesh Agron. J. 2015, 18(2): 31-38