Background: Salinity is a stressful environmental factor that limits the productivity of crop plants, and roots form the major interface between plants and various abiotic stresses. Rice is a salt-sensitive crop and its polyploid shows advantages in terms of stress resistance. The objective of this study was to investigate the effects of genome duplication on rice root resistance to salt stress. Results: Both diploid rice (HN2026-2x and Nipponbare-2x) and their corresponding tetraploid rice (HN2026-4x and Nipponbare-4x) were cultured in half-strength Murashige and Skoog medium with 150 mM NaCl for 3 and 5 days. Accumulations of proline, soluble sugar, malondialdehyde (MDA), Na⁺ content, H⁺ (proton) flux at root tips, and the microstructure and ultrastructure in rice roots were examined. We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice. In addition, a protective gap appeared between the cortex and pericycle cells in tetraploid rice. Next, ultrastructural analysis showed that genome duplication improved membrane, organelle, and nuclei stability. Furthermore, Na⁺ in tetraploid rice roots significantly decreased while root tip H⁺ efflux in tetraploid rice significantly increased. Conclusions: Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na⁺ entrance into the roots.

Soybean genotypes show diverse physiological responses to drought, but specific physiological traits that can be used to evaluate drought tolerance have not been identified. In the present study we investigated physiological traits of soybean genotypes under progressive soil drying and rewetting, using a treatment mimicking field conditions. After a preliminary study with eight soybean genotypes, two drought-tolerant genotypes and one susceptible genotype were grown in the greenhouse and subjected to water restriction. Leaf expansion rate, gas exchange, water relation parameters, total chlorophyll (Chl), proline contents of leaves, and root xylem pH were monitored in a time course, and plant growth and root traits were measured at the end of the stress cycle. Drought-tolerant genotypes maintained higher leaf expansion rate, net photosynthetic rate (Pn), Chl content, instantaneous water use efficiency (WUEi), % relative water content (RWC), water potential (ψw), and turgor potential (ψp) during progressive soil drying and subsequent rewetting than the susceptible genotypes. By contrast, stomatal conductance (gs) and transpiration rate (Tr) of tolerant genotypes declined faster owing to dehydration and recovered more sharply after rehydration than the same parameters in susceptible ones. Water stress caused a significant increase in leaf proline level and root xylem sap pH of both genotypes but tolerant genotypes recovered to pre-stress levels more quickly after rehydration. Tolerant genotypes also produced longer roots with higher dry mass than susceptible genotypes. We conclude that rapid perception and adjustment in response to soil drying and rewetting as well as the maintenance of relatively high Pn, %RWC, and root growth constitute the mechanisms by which drought-tolerant soybean genotypes cope with water stress

The impact of chemical farming and the negative consequences on the environment and human health in Bangladesh are on the rise. Organic farming is gaining attention and increasing globally because it is eco-friendly, safe and has benefits for human health. A field study was conducted at the horticulture farm of Bangladesh Agricultural University (BAU), Mymensingh, to evaluate the growth and yield performance of cabbage cv. Atlas—70 using organic and inorganic fertilizers in various plant spacing arrangements. Two factor experiments were conducted on plant spacings of 60 cm × 40 cm (S₁), 60 cm × 50 cm (S₂) and 60 cm × 60 cm (S₃) and fertilizers vermicompost (T₁), biogen (T₂), integrated plant nutrient system (IPNS) Organic (⅔) + inorganic (⅓) (T₃) and inorganic (T₄). IPNS (T₃) application increased the marketable yield (54.77 t·ha⁻¹) of cabbage. The highest marketable yield (48.75 t·ha⁻¹) was obtained with a plant spacing of 60 cm × 40 cm (S₁). No significant variation was found in plant spacings S₁ and S₂. The treatment combination of S₂T₃ recorded the highest plant height (37.81 cm), plant spread (47.75 cm), cabbage head (21.80 cm), stem length (12.31 cm), thickness of the cabbage head (12.53 cm) and marketable yield (65.0 t·ha⁻¹). The results suggest that IPNS (T₃) combining organic and inorganic fertilizer applications with a 60 cm × 50 cm spacing (S₂T₃) increases the yield performance of cabbage.

The purpose of this study was to investigate the physiological responses of drought-tolerant and drought-susceptible soybean genotypes to exogenous abscisic acid (ABA) application during progressive soil drying at seedling stages. Five-day old soybean seedlings were transplanted into PVC tubes filled with soil mixture. Seedlings were watered daily with similar water volumes until second trifoliate leaves emerged, and thereafter soil drying with or without exogenous ABA application was imposed. Half of the seedlings of each genotype were left for regular watering as control plants. Soil water status declined significantly over seven days of withholding water supply for both genotypes. Leaf expansion rate, stomatal conductance (gs), leaf water potential (ψw), and relative water content of leaves (%RWC) declined significantly under soil drying as well as soil drying with ABA application, compared to their values for well-watered soybean genotypes. However, a drought-tolerant genotype (C12) responded more rapidly than a drought-susceptible genotype (C08) after imposition of soil drying and soil drying with exogenous ABA. In addition, application of exogenous ABA to water-restricted soybeans resulted in higher %RWC and ψw in the drought-tolerant than in the drought-susceptible genotype. Compared to the drought-susceptible genotype, the drought-tolerant genotype was more responsive to exogenous ABA application, resulting in a higher root-to-shoot ratio

Salinity is a major constraint in crop production in saline prone areas of Bangladesh. Therefore, a study was carried out in order to investigate the effect of different levels of NaCl salinity stress on seed germination and seedling growth of tomato. This study was consisted with five varieties of tomato (BARI Tomato-2, BARI Tomato-3, BARI Tomato-4, BARI Tomato-14, and BARI Tomato-15) and four levels of NaCl salt solution (0, 50, 100 and 150 mM). Seeds were placed in petridish for germination and the seedlings were allowed to grow for ten days. Results showed that percent seed germination decreased with increasing salt concentration in the germinating media. The highest seed germination (68.25%) was recorded in untreated control (0 mM) condition and the lowest in 150 mM salt solution ((5.92%). In combination of variety and salt concentration, BARI Tomato-2 gave the highest germination (88.33%) under 0 mM salinity condition and the lowest (2.92%) in BARI Tomato-3 with 150 mM salt solution. However, percent germination, germination coefficient, radicle and plumule length, seedling vigor index, fresh weight of plumule and radicle, mean germination time, germination index decreased with increasing salt concentration as compared to untreated control condition. The findings indicated that BARI Tomato- 2, BARI Tomato-4 and BARI Tomato-15 were relatively tolerant to salt stress than BARI Tomato-3 and BARI Tomato-14. J Bangladesh Agril Univ 17(4): 490–499, 2019