Hakan Altunlu

Bio: Hakan Altunlu is an academic researcher from Muğla University. The author has contributed to research in topics: Membrane permeability & Crop yield. The author has an hindex of 8, co-authored 18 publications receiving 666 citations.

Comparative effects of various salicylic acid derivatives on key growth parameters and some enzyme activities in salinity stressed maize (Zea mays L.) plants

Abstract: Salicylic acid, 5-Sulfo Salicylic acid and Acetylsalicylic acid are Salicylic acid derivatives. They differ in their substitution on the benzene ring and may have different effects on plant membranes. The effects of the derivatives of various Salicylic Acid [Salicylic acid (SA), 5-Sulfo Salicylic Acid (SSA) and Acetylsalicylic Acid (ASA)] on antioxidant enzyme activities, mineral element uptake, growth and some stress related parameters of maize (Zea mays L. cv. DK 684) plant grown in containers under salinity stress were investigated. Salicylic acid were applied by foliar treatments at five days interval. Treatments were: 1-) control, 2-) salt treatment 125 mM NaCl, 3-)125 mM NaCl + 1 mM Salicylic Acid, 4-)125 mM NaCl + 1 mM Sulfo Salicylic Acid, 5)125 mM NaCl + 1 mM Acetylsalicylic Acid, 6-) 125 mM NaCl + 2 mM Salicylic Acid, 7-)125 mM NaCl + 2 mM Sulfo Salicylic Acid and 8-) 125 mM NaCl + 2 mM Acetylsalicylic Acid. Salt treatment reduced the plant growth, chlorophyll content, relative water content and ear of corn weight, but increased antioxidative enzymes and membrane permeability. Besides compared with the control group, nutrient uptakes of leaves and roots were inhibited by salt treatment. Tested parameters were generally positively affected by the applications of the salicylic acid derivatives compared to the salt treatment. For example, total chlorophyll, shoot dry matter, relative water content and ear of corn weight were ameliorated by 1 and 2 mM SSA, 1 mM ASA and 1 mM SSA treatments. The macro and micro element content of leaves and roots were generally increased by salicylic acid treatments compared to the salt treatment. Salicylic acid application seems to be more effective in the element uptakes than other ones. Salicylic acid treatments decreased antioxidant enzyme activities compared to the salt treatment. The data clearly shows that, the various derivatives of salicylic acid could protect maize plant from the detrimental effects of salt stress by improving physiological parameters tested such as relative water content, membrane permeability and nutrient status of plant.

Mitigation effects of non-enzymatic antioxidants in maize (Zea mays L.) plants under salinity stress

Abstract: The effects of non-enzymatic antioxidative compounds such as ascorbic acid, thiamine HCl and beta-carotene were investigated on salt stressed maize plants. The maize plants were sprayed with 100 mg L−1 of ascorbic acid, thiamine or beta-carotene solutions once a week, up to harvesting of plants. The treatment of NaCl was initiated 25 days after sowing by irrigating the plants with 125 mM NaCl solution. Plants for physiological and biochemical measurements were harvested at the cob formation stage and for yield 90 days after seedling emergence. The results showed that although salt stress reduced the shoot and root dry weights and macro-element contents of maize plants, exogenous application of non-enzymatic antioxidants improved the above-mentioned parameters of maize plants under saline conditions. Shoot and root dry weights increased significantly (P < 0.05) by the ascorbic acid treatments. Salt stress enhanced the activities of superoxide dismutase (SOD; EC: 1.15.1.1), peroxidase (POX; EC: 1.11.1.7) and polyphenol oxidase (PPO; EC: 1.10.3.1). Proline content also increased significantly in maize plants in response to NaCl stress. Although the SOD activity increased significantly with ascorbic acid treatment, the POX activity increased considerably with beta-carotene application. Of the non-enzymatic antioxidative compounds tested, ascorbic acid was more effective than the others in protecting maize plants from salinity stress. The results of the present study indicate that foliar application of non-enzymatic antioxidative compounds alleviated the detrimental effects of salinity and increased resistance to salinity in the maize plants by improving the antioxidative defense system.

Responses of the Tomato (Lycopersicon esculentum Mill.) Plant to Exposure to Different Salt Forms and Rates

Abstract: We aimed to investigate the effects of NaCl and Na2SO4 on seed and pollen germination of tomato (Lycopersicon esculentum Mill.) in vitro. In addition, the effects of NaCl, Na2SO4, and CaCl2 on yield and quality, plant growth, some physiological parameters, and the distribution of mineral composition in greenhouse grown tomato plants were investigated. Seed germination was affected by high salinity treatments (MS and 1/2 MS). Pollen germination and pollen tube length were significantly affected by salt forms and doses. Pollen germination was blocked by the above doses of 50 mM NaCl and 30 mM Na2SO4. In the greenhouse experiment, with increasing concentration of all forms of salt, stomatal density, chlorophyll content, plant growth, and yield decreased. Reductions were higher in fruit yield and stomatal density in the NaCl treatment than those in Na2SO4 and CaCl2 treatments. Membrane permeability was impaired with increases in all 3 forms of salt concentrations, but the effect of NaCl treatment on membrane permeability was more striking compared to the other salt forms. Proline accumulation increased with increasing salt concentrations. The K and N concentrations decreased with increases in all 3 types of salt concentrations. Concentration of Ca decreased with increasing NaCl and Na2SO4, but increased with CaCl2 salt concentrations. The growth and yield reduction under both NaCl and Na2SO4 stress may be due to the combined effects of lower rates of Ca, K, and N, and excess accumulation of Na, while in the CaCl2 experiment the growth reduction may be related to lower rates of K and N and the high rate of Ca.

Effect of salinity stress on plants and its tolerance strategies: a review.

Abstract: The environmental stress is a major area of scientific concern because it constraints plant as well as crop productivity. This situation has been further worsened by anthropogenic activities. Therefore, there is a much scientific saddle on researchers to enhance crop productivity under environmental stress in order to cope with the increasing food demands. The abiotic stresses such as salinity, drought, cold, and heat negatively influence the survival, biomass production and yield of staple food crops. According to an estimate of FAO, over 6 % of the world’s land is affected by salinity. Thus, salinity stress appears to be a major constraint to plant and crop productivity. Here, we review our understanding of salinity impact on various aspects of plant metabolism and its tolerance strategies in plants.

Soil Salinity: Effect on Vegetable Crop Growth. Management Practices to Prevent and Mitigate Soil Salinization

Abstract: Salinity is a major problem affecting crop production all over the world: 20% of cultivated land in the world, and 33% of irrigated land, are salt-affected and degraded. This process can be accentuated by climate change, excessive use of groundwater (mainly if close to the sea), increasing use of low-quality water in irrigation, and massive introduction of irrigation associated with intensive farming. Excessive soil salinity reduces the productivity of many agricultural crops, including most vegetables, which are particularly sensitive throughout the ontogeny of the plant. The salinity threshold (ECt) of the majority of vegetable crops is low (ranging from 1 to 2.5 dS m−1 in saturated soil extracts) and vegetable salt tolerance decreases when saline water is used for irrigation. The objective of this review is to discuss the effects of salinity on vegetable growth and how management practices (irrigation, drainage, and fertilization) can prevent soil and water salinization and mitigate the adverse effects of salinity.

Some Prospective Strategies for Improving Crop Salt Tolerance

Abstract: Soil salinity is a major environmental constraint to crop productivity worldwide. The “biological” approach to this problem focuses on the management, exploitation, or development of plants able to thrive on salt‐affected soils. This chapter reviews strategies by which plants can be enabled to grow on saline soils. The first strategy is to prime seeds before planting by treating them with inorganic or organic chemicals and/or with high or low temperatures. The second strategy involves exogenous application of organic chemicals, such as glycine betaine, proline, or plant growth regulators, or inorganic chemicals to plants under salinity stress. Considerable improvements in growth and yield have been reported in a number of crops using these approaches. The third strategy is to employ selection and breeding. Major efforts have been made to develop salt‐tolerant lines or cultivars of crops using conventional plant breeding. However, the complexity of the tolerance mechanisms, lack of selection criteria, and variation in responses of plants at different developmental stages have resulted in only limited success. The emphases for developing salt‐tolerant lines/cultivars are now on marker‐assisted breeding and genetic transformation. The development of salt‐tolerant transgenic plants is still at an early stage but may become increasingly more effective as better knowledge of the complex mechanisms involved in plant salt tolerance is acquired. Furthermore, the rapid expansion in knowledge on genomics and proteomics will undoubtedly accelerate the transgenic and molecular breeding approaches However, to date, there are few conclusive reports indicating successful performance of transgenic cultivars under natural stressful environments.

Ascorbate Peroxidase and Catalase Activities and Their Genetic Regulation in Plants Subjected to Drought and Salinity Stresses

Abstract: Hydrogen peroxide (H2O2), an important relatively stable non-radical reactive oxygen species (ROS) is produced by normal aerobic metabolism in plants. At low concentrations, H2O2 acts as a signal molecule involved in the regulation of specific biological/physiological processes (photosynthetic functions, cell cycle, growth and development, plant responses to biotic and abiotic stresses). Oxidative stress and eventual cell death in plants can be caused by excess H2O2 accumulation. Since stress factors provoke enhanced production of H2O2 in plants, severe damage to biomolecules can be possible due to elevated and non-metabolized cellular H2O2. Plants are endowed with H2O2-metabolizing enzymes such as catalases (CAT), ascorbate peroxidases (APX), some peroxiredoxins, glutathione/thioredoxin peroxidases, and glutathione sulfo-transferases. However, the most notably distinguished enzymes are CAT and APX since the former mainly occurs in peroxisomes and does not require a reductant for catalyzing a dismutation reaction. In particular, APX has a higher affinity for H2O2 and reduces it to H2O in chloroplasts, cytosol, mitochondria and peroxisomes, as well as in the apoplastic space, utilizing ascorbate as specific electron donor. Based on recent reports, this review highlights the role of H2O2 in plants experiencing water deficit and salinity and synthesizes major outcomes of studies on CAT and APX activity and genetic regulation in drought- and salt-stressed plants.

Sodium transport in plants: a critical review

Abstract: Sodium (Na) toxicity is one of the most formidable challenges for crop production world-wide. Nevertheless, despite decades of intensive research, the pathways of Na(+) entry into the roots of plants under high salinity are still not definitively known. Here, we review critically the current paradigms in this field. In particular, we explore the evidence supporting the role of nonselective cation channels, potassium transporters, and transporters from the HKT family in primary sodium influx into plant roots, and their possible roles elsewhere. We furthermore discuss the evidence for the roles of transporters from the NHX and SOS families in intracellular Na(+) partitioning and removal from the cytosol of root cells. We also review the literature on the physiology of Na(+) fluxes and cytosolic Na(+) concentrations in roots and invite critical interpretation of seminal published data in these areas. The main focus of the review is Na(+) transport in glycophytes, but reference is made to literature on halophytes where it is essential to the analysis.