Melek Ekinci

Plant growth-promoting rhizobacteria improved growth, nutrient, and hormone content of cabbage (Brassica oleracea) seedlings

Metin TURAN, Melek EKİNCİ, Ertan YILDIRIM*, Adem GÜNEŞ, Kenan KARAGÖZ, Recep KOTAN, Atilla DURSUN Department of Genetics and Bioengineering, Faculty of Engineering and Architecture, Yeditepe University, Kayışdağı, İstanbul, Turkey Department of Horticulture, Faculty of Agriculture, Atatürk University, Erzurum, Turkey Department of Soil Science, Faculty of Agriculture, Erciyes University, Kayseri, Turkey Department of Plant Protection, Faculty of Agriculture, Atatürk University, Erzurum, Turkey

Effects of Boron Fertilizer on Tomato, Pepper, and Cucumber Yields and Chemical Composition

In many parts of the world, boron (B) levels are insufficient for potential production. Boron deficiency is also widespread in the Anatolia region of Turkey. Boron deficiency could impact production and quality of tomatoes (Lycopersicon esculentum L.), pepper (Capsicum annum L.), and cucumber (Cucumis sativus L.). A two-year greenhouse experiment was conducted to study yield and quality response of three vegetables to B addition (0, 1, 2, 3, and 4 kg B ha−1). The optimum economic B rates (OEBR) were 2.3, 2.6, 2.4 kg B ha−1, resulting in soil B concentrations of 0.33, 0.34 and 0.42 mg kg−1. Independent of plant species, B application decreased tissue nitrogen (N), calcium (Ca), and magnesium (Mg) but increased tissue phosphorus (P), potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations. We conclude that a B addition of 2.5 kg ha−1 is sufficient to elevate soil B levels to nondeficient levels. Similar studies with different soils and initial soil-test B levels are needed to conclude if these critical soil test values and OEBR can be applied across the region.

Antimicrobial Activities of Essential Oil and Hexane Extract of Florence Fennel [Foeniculum vulgare var. azoricum (Mill.) Thell.] Against Foodborne Microorganisms

The objective of this study was to determine the chemical compositions of the essential oil and hexane extract isolated from the inflorescence, leaf stems, and aerial parts of Florence fennel and the antimicrobial activities of the essential oil, hexane extract, and their major component, anethole, against a large variety of foodborne microorganisms. Gas chromatography and gas chromatography-mass spectrometry analysis showed that the essential oils obtained from inflorescence, leaf stems, and whole aerial parts contained (E)-anethole (59.28-71.69%), limonene (8.30-10.73%), apiole (trace to 9.23%), beta-fenchyl acetate (3.02-4.80%), and perillene (2.16-3.29%) as the main components. Likewise, the hexane extract of the plant sample exhibited a similar chemical composition, and it contained (E)-anethole (53.00%), limonene (27.16%), gamma-terpinene (4.09%), and perillene (3.78%). However, the hexane extract also contained less volatile components such as n-hexadecanoic acid (1.62%), methyl palmitate (1.17%), and linoleic acid (1.15%). The in vitro antimicrobial assays showed that the essential oil, anethole, and hexane extract were effective against most of the foodborne pathogenic, saprophytic, probiotic, and mycotoxigenic microorganisms tested. The results of the present study revealed that (E)-anethole, the main component of Florence fennel essential oil, is responsible for the antimicrobial activity and that the essential oils as well as the hexane extract can be used as a food preservative. This study is the first report showing the antimicrobial activities of essential oil and hexane extract of Florence fennel against probiotic bacteria.

Roles of glycine betaine in mitigating deleterious effect of salt stress on lettuce (Lactuca sativa L.)

This study was conducted to evaluate the roles of glycine betaine (GB) in mitigating deleterious effect of salt stress on lettuce. Lettuce plants were subjected to two salinity (0 and 100 mmol l−1 NaCl) and four GB levels (0, 5, 10, 25 mmol l−1). Salinity resulted in a remarkable decrease in growth parameters, relative leaf water content and stomatal conductance. Plants subjected to salt stress exhibited an increase in membrane permeability (MP), lipid peroxidation (MDA), leaf chlorophyll reading value, H2O2 and sugar content. Exogenous foliar applications of GB reduced MP, MDA and H2O2 content in salt-stressed lettuce plants. Salt stress increased Na and generally decreased other nutrient elements. GB reduced Na accumulation, but significantly increased other element contents under salinity conditions. The study showed that gibberellic acid (GA) and salicylic acid (SA) content in salt-stressed plants were lower than those of nonstressed plants. However, salinity conditions generally increased the abscisic acid content. GB treatments elevated the concentrations of GA, SA and indole acetic acid (IAA) at especially 10 and 25 mmol l−1 GB under salt stress conditions. It could be concluded that exogenous GB applications could ameliorate the harmful effects of salt stress in lettuce.

Exogenously applied glycine betaine regulates some chemical characteristics and antioxidative defence systems in lettuce under salt stress

We investigated the effects of exogenous glycine betaine (GB) applications on antioxidant enzyme activity, dry matter, and the contents of organic acids, amino acids, total antioxidants, and total phenolics in lettuce, Lactuca sativa, under salt stress. The treatments included four concentrations of GB (0, 5, 10, and 25 mM) and two levels of salinity (0 and 100 mM of NaCl). The 25 mM GB treatment increased dry matter and the content of total phenolics in lettuce plants compared to the non-GB-treated plants under salt stress. Salinity (100 mM NaCl without GB) significantly reduced dry matter, total phenolic content, and total antioxidant content in the plants. However, the lettuce plants grown under salt stress generally had higher amino acid and organic acid contents than those grown under non-salinity conditions. GB treatments had different effect on amino acid and organic acid contents under salinity conditions. Superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities were elevated under the 100 mM NaCl and 0 mM GB treatments, whereas higher concentrations of GB decreased them under salt stress. The 25 mM GB treatment mitigated the negative effect of salt stress and increased the dry matter by 44% compared to the plants that were treated with 100 mM NaCl and 0 mM GB. The results suggested that exogenous GB treatments could ameliorate the tolerance of lettuce to salt stress by increasing the total antioxidants and total phenolics, and regulating antioxidant enzyme activity, and altering the contents of organic acids and amino acids.

Responses to the Irrigation Water Amount of Spinach Supplemented with Organic Amendment in Greenhouse Conditions

The effect of organic amendment applications on some agrophysiological properties of pot-grown spinach was investigated under drought stress. The I1, I2, I3, and I4 irrigation treatments received water amounts up to 100, 80, 60, and 40 percent of evaporation from a reduced pan, respectively. A liquid organic amendment was applied to spinach seeds as seed treatment at the ratios of 0.1 percent (H1) and 0.2 percent (H3). Furthermore, in the H2 and H4 treatments the amendment was foliar applied to spinach seedlings at the ratios of 0.1 percent and 0.2 percent in addition to the seed treatments, respectively. Organic amendment treatments positively affected root and leaf growth. The plants responded to water stress by lower growth. Leaf relative water content, membrane permeability, chlorophyll reading, and stomatal conductance values also indicated significant changes. These results support the view that organic amendment application increased growth. However, it could not provide a significant contribution for growth under water stress.

Integrated Use of Nitrogen Fertilization and Microbial Inoculation: Change in the Growth and Chemical Composition of White Cabbage

ABSTRACT Field experiments were conducted to evaluate the impact of seed and seedling inoculation by plant growth promoting rhizobacteria (PGPR) on nitrogen use efficiency, growth, yield, and chemical composition of cabbage at varying levels of nitrogen (N). Data revealed that N alone or in combination with PGPR either as seed or seedling inoculation significantly improved growth, yield, and nutrients of cabbage. PGPR inoculations were more efficient than non-inoculated controls in terms of yield and yield parameters. This study showed that seed and seedling inoculation increased yield and yield parameters as well as chlorophyll reading value and stomatal conductance versus controls. Applications of mineral fertilizers with microbial applications save 25% of mineral fertilizers yet give 33% more yield versus full doses of mineral application without microbial applications. Both seed and seedling treatments increased the nitrogen use efficiency (NUE) rates by 45, 53, 58, 45, and 40%, and 49, 59, 68, 69, 60, and 55%, respectively.

Changes in gas exchange capacity and selected physiological properties of squash seedlings (Cucurbita pepo L.) under well-watered and drought stress conditions

ABSTRACT Water use efficiency (WUE) is considered as an important component of adaptation to drought stress. This study was conducted to determine the effect of drought stress on gas exchange parameters and selected physiological properties, and also its relations with WUE in summer squash seedlings (Cucurbita pepo L.). Plants were grown in pots under different irrigation levels (D0: 100%, D1: 67% and D2: 33% of the water required to reach the field capacity) in controlled greenhouse. The results show that drought treatments significantly decreased the leaf chlorophyll reading values (LCRV), leaf relative water content (LRWC), stomatal conductance (gs), photosynthetic rate (PN), transpiration rate (Tr), fresh weight (FW) and dry weight (DW) of squash seedlings by 7, 42, 69, 62, 62 63 and 82%, respectively, in D2 treatment compared to D0. However, electrolyte leakage (EL) values increased 72% with severe drought treatments (D2). The highest WUE was obtained by D0 treatment as 0.26 g mm−1. The relationship between PN and WUE is the strongest one among all leaf gas exchange parameters. Together with Tr, the linear relation with WUE was considerably higher compared to other measured parameters.

Nitrik Oksit Uygulamalarının Bitkilerde Abiyotik Stres Şartlarına Toleransı Arttırmadaki Etkileri

Gunumuzde bitkisel uretimini sinirlandiran cevresel stres faktorleri nedeniyle, yetistiricilikte bitkinin normal urun potansiyeline ulasmasini saglayacak uygun alanlarin bulunmasi oldukca zorlasmistir. Tarimsal uretimin azalmasinda cok buyuk oranda abiyotik stres, daha dusuk oranlarda ise diger stres faktorleri etkilidir. Abiyotik stres faktorleri olarak, kuraklik, tuzluluk, yuksek ve dusuk sicaklik, sel, radyasyon, agir metaller, oksidatif stres, ruzgâr, besin maddesi eksikligi gibi faktorler sayilabilir ve bu stres kaynaklari bitki gelisimini, kaliteyi ve verimliligi olumsuz yonde etkilemektedir. Gaz halindeki farkli bilesikler arasinda, nitrik oksitin (NO) bitkilere disaridan uygulanmasi son yillarda daha fazla onem kazanmistir. NO tohum cimlenmesi ve fide buyumesinin iyilestirilmesi gibi bitkilerde duzenleyici rollerinin yani sira, metal toksisitesi, sicaklik, kuraklik ve tuzluluk gibi farkli abiyotik streslere karsi da koruyucu bir rol oynamaktadir. Bu makalede bitkilerin kuraklik, tuzluluk, yuksek ve dusuk sicaklik ile agir metaller gibi abiyotik stres kosullarinda NO uygulamalarinin etkileri tartisilmistir.

Nitrogen fertilization and plant growth promoting rhizobacteria treatments affected amino acid content of cabbage

This study was designed to determine the influence of a nitrogen fixing plant growth promoting rhizobacteria (PGPR) inoculation (seed coating and seedling dipping) and 6 doses of nitrogen (0, 40, 80, 120, 160, 200 kg ha−1) application on amino acid contents of cabbage. Coating and seedling dipping applications caused a significant increase in values histidine, glycine, thionin, arginine and alanine of cabbage. Highest glutamate, serine, asparagines and glutamine contents were obtained from 160-200 kg ha−1 nitrogen dose applied plants. As a result, the use of bacteria treatments provides means of improving amino acid contents in cabbage.