Selim Eker

Differential response of rye, triticale, bread and durum wheats to zinc deficiency in calcareous soils

Field and greenhouse experiments were carried out to study the response of rye (Secale cereale L. cv. Aslim), triticale (× Triticosecale Wittmark. cv. Presto), two bread wheats (Triticum aestivum L, cvs. Bezostaja-1 and Atay-85) and two durum wheats (Triticum durum L. cvs. Kunduru-1149 and C-1252) to zinc (Zn) deficiency and Zn fertilization in severely Zn-deficient calcareus soils (DTPA-Zn=0.09 mg kg-1 soil). The first visible symptom of Zn deficiency was a reduction in shoot elongation followed by the appearance of whitish-brown necrotic patches on the leaf blades. These symptoms were either absent or only slight in rye and triticale, but occurred more rapidly and severely in wheats, particularly in durum wheats. The same was true for the decrease in shoot dry matter production and grain yield. For example, in field experiments at the milk stage, decreases in shoot dry matter production due to Zn deficiency were absent in rye, and were on average 5% in triticale, 34% in bread wheats and 70%, in durum wheats. Zinc fertilization had no effect on grain yield in rye but enhanced grain yield of the other cereals. Zinc efficiency of cereals, expressed as the ratio of yield (shoot dry matter or grain) produced under Zn deficiency compared to Zn fertilization were, on average, 99% for rye, 74% for triticale, 59% for bread wheats and 25% for durum wheats.These distinct differences among and within the cereal species in susceptibility to Zn deficiency were closely related to the total amount (content) of Zn per shoot, but not with the Zn concentrations in shoot dry matter. For example, the most Zn-efficient rye and the Zn-inefficient durum wheat cultivar C-1252 did not differ in shoot Zn concentration under Zn deficiency, but the total amount of Zn per whole shoot was approximately 6-fold higher in rye than the durum wheat. When Zn was applied, rye and triticale accumulated markedly more Zn both per whole shoot and per unit shoot dry matter in comparison to wheats.The results demonstrate an exceptionally high Zn efficiency of rye and show that among the cereals studied Zn efficiency declines in the order rye>triticale>bread wheat>durum wheat. The differences in expression of Zn efficiency are possibly related to a greater capacity of efficient genotypes to acquire Zn from the soil compared to inefficient genotypes.

Dry matter production and distribution of zinc in bread and durum wheat genotypes differing in zinc efficiency

Six bread wheat (Triticum aestivum cvs. Kiraç-66, Gerek-79, Aroona, ES 91-12, ES-14 and Kirkpinar) and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-1149, Kiziltan-91 and Durati) genotypes were grown under controlled environmental conditions in nutrient solution for 20 days to study the effect of varied supply of Zn (0 to 1 µM) on Zn deficiency symptoms in shoots, root and shoot dry matter production, and distribution of Zn in roots and shoots.Visual Zn deficiency symptoms, such as whitish-brown lesions on leaves, appeared rapidly and severly in durum wheats, particularly in Kiziltan-91 and Durati. Among the durum wheats, BDMM-19 was less affected by Zn deficiency, and among the bread wheats Kiraç-66, ES 91-12, Aroona and Gerek-79 were less affected than ES-14 and Kirkpinar.Under Zn deficiency, shoot dry matter production was decreased in all genotypes, but more distinctly in durum wheat genotypes. Despite severe decreases in shoot growth, root growth of all genotypes was either not affected or even increased by Zn deficiency. Correspondingly, shoot/root dry weight ratios were lower in Zn-deficient than in Zn-sufficient plants, especially in durum wheat genotypes.The distinct differences among the genotypes in sensitivity to Zn deficiency were closely related with the Zn content (Zn accumulation) per shoot but not with the Zn concentration in the shoot dry matter. On average, genotypes with lesser deficiency symptoms contained about 42% more Zn per shoot than genotypes with severe deficiency symptoms. In contrast to shoots, the Zn content in roots did not differ between genotypes. Shoot/root ratios of total Zn content were therefore greater for genotypes with lesser deficiency symptoms than for genotypes with severe deficiency symptoms (i.e. all durum wheat genotypes).The results suggest that the enhanced capacity of genotypes for Zn uptake and translocation from roots to shoot meristems under deficient Zn supply might be the most important factor contributing to Zn efficiency in wheat genotypes. The results also demonstrate that under severe Zn deficiency, Zn concentration in the shoot dry matter is not a suitable parameter for distinguishing wheat genotypes in their sensitivity to Zn deficiency.

PHYTIC ACID AND PHOSPHORUS CONCENTRATIONS IN SEEDS OF WHEAT CULTIVARS GROWN WITH AND WITHOUT ZINC FERTILIZATION

Seeds of twenty wheat cultivars grown with (+Zn = 23 kg Zn ha−1) and without zinc (Zn) fertilization in a Zn-deficient calcareous soil in Central Anatolia were analyzed for the levels of Zn, phosphorus (P), phytic acid, and phytase activity. Additionally, seeds of four wheat cultivars grown on 55 different locations in Turkey were also analyzed for Zn, P, and phytic acid. In the field experiment with 20 wheat cultivars, seed Zn concentrations showed a range between 7 to 11 mg kg−1 under Zn-deficient and 14 to 23 mg kg−1 under Zn-added conditions. Zinc fertilization reduced seed concentrations of P and phytic acid of all cultivars. On average, the reductions caused by Zn fertilization were from 3.9 to 3.5 mg g−1 for P and from 10.7 to 9.1 mg g−1 for phytic acid. Irrespective of Zn fertilization, seed phytic acid concentrations showed a large genotypic variation, i.e., from 7 to 12 mg g−1 with Zn fertilization and 8 to 13 mg g−1 at nil Zn treatment. As a result of decreases in phytic acid and increases in Zn concentrations by Zn fertilization, phytic acid to Zn molar ratios in seeds of cultivars markedly decreased. On average for all cultivars, phytic acid to Zn molar ratios decreased from 126 to 56 with Zn fertilization. Seed phytase activity of cultivars was not consistently influenced by varied Zn supply. However, on average for 20 cultivars, Zn fertilization tended to decrease phytase activity. In seeds of four wheat cultivars collected from 55 locations, the concentrations of Zn, P, and phytic acid ranged from 8 to 34 mg kg−1, 2.1 to 4.9 mg g−1, and 5.8 to 14.3 mg kg−1, respectively. Results obtained in the present study indicate that seed Zn concentrations of wheat cultivars grown in different locations of Turkey, especially under Zn-deficient conditions, are very low. Considering very high phytic acid : Zn molar ratios it can be suggested that bioavailability of Zn would be very low for humans. *Dedicated to the memory of the late Professor Dr. Ferhan Hatipoglu.

Concentration of zinc and activity of copper/zinc-superoxide dismutase in leaves of rye and wheat cultivars differing in sensitivity to zinc deficiency

Summary Two bread wheat ( Triticum aestivum L. cvs. Bezostaja-1 and BDME-10), two durum wheat ( Triticum durum L. cvs. Kunduru-1149 and Kiziltan-91) and one rye ( Secale cereale L. cv. Ashm) cultivars differing in sensitivity to zinc (Zn) deficiency were grown under controlled environmental conditions for 21 days in a Zn deficient soil to compare severity of Zn deficiency symptoms with the concentration of total Zn and activities of total superoxide dismutase (SOD), copper (Cu) and Zn containing SOD (Cu/Zn-SOD) and manganese (Mn) containing SOD (Mn-SOD) in leaves. Visual Zn deficiency symptoms such as development of whitish-brown necrotic patches on leaf blades appeared rapidly and were severe in bread wheat cultivar BDME-10 and particularly in both durum wheat cultivars, while Bezostaja-1 was much less affected by Zn deficiency. In the case of rye, the leaf symptoms were either absent or only slightly developed. The effect of Zn deficiency on shoot dry matter production was very similar to the effect on leaf symptoms. Decreases in shoot dry matter production as a result of Zn deficiency were about 16 % in Ashm (rye) and Bezostaja-1, 36 % in BDME-10 and 47% in durum wheats. Despite of such marked differences in sensitivity to Zn deficiency, concentrations of Zn in leaf dry matter were not different between the cultivars under Zn deficiency. However, activities of Cu/Zn-SOD and, in part, total SOD, but not Mn-SOD were very closely related with the sensitivity of cultivars to Zn deficiency. Under Zn deficiency, rye showing a high resistance to Zn deficiency had the greatest activity of Cu/Zn-SOD. Among the wheat cultivars, Bezostaja-1 with less sensivity to Zn deficiency showed higher activity of Cu/Zn-SOD than other wheat cultivars. The results suggested that Zn efficient cereal genotypes possess higher amounts of physiologically active Zn in leaves and that activity of Cu/Zn-SOD is a better indicator of Zn nutritional status of plants than Zn concentration alone. An efficient utilization of Zn at the cellular level seems to be a major factor determining expression of Zn efficiency in cereals growing under deficient supply of Zn.

EFFECTS OF ZINC FERTILIZATION ON GRAIN YIELD AND SHOOT CONCENTRATIONS OF ZINC, BORON, AND PHOSPHORUS OF 25 WHEAT CULTIVARS GROWN ON A ZINC-DEFICIENT AND BORON-TOXIC SOIL

Field experiments were carried out to study the grain yield, shoot concentrations of zinc (Zn), boron (B) and phosphorus (P), and tolerance to Zn deficiency of 21 bread wheat (Triticum aestivum) and four durum wheat (Triticum durum) cultivars grown in a B-toxic and Zn-deficient calcareous soil in Central Anatolia with (+Zn = 23 kg Zn ha−1) and without Zn fertilization in 1993–1994 and 1994–1995 cropping seasons. Tolerance to Zn deficiency (Zn efficiency ratio) was measured by considering the ratio of grain yield under Zn deficiency to that with Zn fertilization. Zinc fertilization significantly increased grain yield of all cultivars in both years. On average, increases in grain yield of 25 wheat cultivars by Zn fertilization were 37% in the first and 40% in the second year. When results of the 2 cropping seasons were averaged, Zn efficiency ratios of the cultivars ranged from 40% to 84%, with an average of 62%. Despite large genotypic variation in Zn efficiency, shoot Zn concentrations under Zn-deficient conditions did not differ among Zn-efficient and Zn-inefficient cultivars. There were large differences in B concentration in shoots of cultivars under both Zn deficiency and Zn fertilization. However, on average for 25 wheat cultivars, Zn fertilization did not influence B concentration. In contrast to B, Zn fertilization consistently decreased shoot concentration of P in all cultivars. The results presented show that wheat cultivars growing in Zn-deficient and B-toxic soil conditions vary considerably in their grain yield, and these differences were not related to the shoot concentrations of Zn and B. Nevertheless, for many cultivars there was a close relationship between tolerance to Zn deficiency and tolerance to B toxicity. This relationship was discussed in terms of high Zn efficiency-enhanced tissue tolerance to B toxicity.

Effects of zinc fertilization and irrigation on grain yield and zinc concentration of various cereals grown in zinc‐deficient calcareous soils

Abstract Effects of varied irrigation and zinc (Zn) fertilization (0, 7, 14, 21 kg Zn ha‐1 as ZnSO47.H2O) on grain yield and concentration and content of Zn were studied in two bread wheat (Triticum aestivum), two durum wheat (Triticum durum), two barley (Hordeum vulgare), two triticale (xTriticosecale Wittmark), one rye (Secale cereale), and one oat (Avena sativa) cultivars grown in a Zn‐deficient soil (DTPA‐extractable Zn: 0.09 mg kg‐1) under rainfed and irrigated field conditions. Only minor or no yield reduction occurred in rye as a result of Zn deficiency. The highest reduction in plant growth and grain yield due to Zn deficiency was observed in durum wheats, followed by oat, barley, bread wheat and triticale. These decreases in yield due to Zn deficiency became more pronounced under rainfed conditions. Although highly significant differences in grain yield were found between treatments with and without Zn, no significant difference was obtained between the Zn doses applied (7–21 kg ha‐1), indicating...

Phytosiderophore release does not relate well with zinc efficiency in different bread wheat genotypes

Abstract Using six bread wheat genotypes (Triticum aesttvum L. cvs. Dagdas‐94, Gerek‐79, BDME‐10, SBVD 1–21, SBVD 2–22 and Partizanka Niska) and one durum wheat genotype (Triticum durum L. cv. Kunduru‐1149) experiments were carried out to study the relationship between the rate of phytosiderophore release and susceptibility of genotypes to zinc (Zn) deficiency during 15 days of growth in nutrient solution with (1 μM Zn) and without Zn supply. Among the genotypes, Dagdas‐94 and Gerek‐79 are Zn efficient, while the others are highly susceptible to Zn deficiency, when grown on severely Zn deficient calcareous soils in Turkey. Similar to the field observations, visual Zn deficiency symptoms, such as whitish‐brown lesions on leaf blades occurred first and severely in durum wheat Kunduru‐1149 and bread wheats Partizanka Niska, BDME‐10, SBVD 1–21 and SBVD 2–22. Visual Zn deficiency symptoms were less severe in the bread wheats Gerek‐79 and particularly Dagdas‐94. These genotypic differences in susceptibility to ...

Glyphosate inhibition of ferric reductase activity in iron deficient sunflower roots

Iron (Fe) deficiency is increasingly being observed in cropping systems with frequent glyphosate applications. A likely reason for this is that glyphosate interferes with root uptake of Fe by inhibiting ferric reductase in roots required for Fe acquisition by dicot and nongrass species. This study investigated the role of drift rates of glyphosate (0.32, 0.95 or 1.89 mm glyphosate corresponding to 1, 3 and 6% of the recommended herbicidal dose, respectively) on ferric reductase activity of sunflower (Helianthus annuus) roots grown under Fe deficiency conditions. Application of 1.89 mm glyphosate resulted in almost 50% inhibition of ferric reductase within 6 h and complete inhibition 24 h after the treatment. Even at lower rates of glyphosate (e.g. 0.32 mm and 0.95 mm), ferric reductase was inhibited. Soluble sugar concentration and the NAD(P)H oxidizing capacity of apical roots were not decreased by the glyphosate applications. To our knowledge, this is the first study reporting the effects of glyphosate on ferric reductase activity. The nature of the inhibitory effect of glyphosate on ferric reductase could not be identified. Impaired ferric reductase could be a major reason for the increasingly observed Fe deficiency in cropping systems associated with widespread glyphosate usage.

Expression of high zinc efficiency of Aegilops tauschii and Triticum monococcum in synthetic hexaploid wheats

The effect of varied zinc (Zn) supply on shoot and root dry matter production, severity of Zn deficiency symptoms and Zn tissue concentrations was studied in two Triticum turgidum (BBAA) genotypes and three synthetic hexaploid wheat genotypes by growing plants in a Zn-deficient calcareous soil under greenhouse conditions with (+Zn=5 mg kg-1 soil) and without (−Zn) Zn supply. Two synthetic wheats (BBAADD) were derived from two different Aegilops tauschii (DD) accessions using same Triticum turgidum (BBAA), while one synthetic wheat (BBAAAA) was derived from Triticum turgidum (BBAA) and Triticum monococcum (AA). Visible symptoms of Zn deficiency, such as occurrence of necrotic patches on leaves and reduction in shoot elongation developed more rapidly and severely in tetraploid wheats than in synthetic hexaploid wheats. Correspondingly, decreases in shoot and root dry matter production due to Zn deficiency were higher in tetraploid wheats than in synthetic hexaploid wheats. Transfer of the DD genome from Aegilops tauschii or the AA genome from Triticum monococcum to tetraploid wheat greatly improved root and particularly shoot growth under Zn-deficient, but not under Zn-sufficient conditions. Better growth and lesser Zn deficiency symptoms in synthetic hexaploid wheats than in tetraploid wheats were not accompanied by increases in Zn concentration per unit dry weight, but related more to the total amount of Zn per shoot, especially in the case of synthetic wheats derived from Aegilops tauschii. This result indicates higher Zn uptake capacity of synthetic wheats. The results demonstrated that the genes for high Zn efficiency from Aegilops tauschii (DD) and Triticum monococcum (AA) are expressed in the synthetic hexaploid wheats. These wheat relatives can be used as valuable sources of genes for improvement of Zn efficiency in wheat.

Diversity of Macro- and Micronutrients in the Seeds of Lentil Landraces

Increasing the amount of bioavailable mineral elements in plant foods would help to improve the nutritional status of populations in developing countries. Legume seeds have the potential to provide many essential nutrients. It is important to have information on genetic variations among different lentil populations so that plant breeding programs can use new varieties in cross-breeding programs. The main objective of this study was to characterize the micro- and macronutrient concentrations of lentil landraces seeds collected from South-Eastern Turkey. We found impressive variation in the micro- and macroelement concentrations in 39 lentil landraces and 7 cultivars. We investigated the relationships of traits by correlation analysis and principal component analysis (PCA). The concentrations of several minerals, particularly Zn, were positively correlated with other minerals, suggesting that similar pathways or transporters control the uptake and transport of these minerals. Some genotypes had high mineral and protein content and potential to improve the nutritional value of cultivated lentil. Cross-breeding of numerous lentil landraces from Turkey with currently cultivated varieties could improve the levels of micro- and macronutrients of lentil and may contribute to the worldwide lentil quality breeding program.