B. Torun

Zinc deficiency as a critical problem in wheat production in Central Anatolia

In a soil and plant survey, and in field and greenhouse experiments the nutritional status of wheat plants was evaluated for Zn, Fe, Mn and Cu in Central Anatolia, a semi-arid region and the major wheat growing area of Turkey.All 76 soils sampled in Central Anatolia were highly alkaline with an average pH of 7. 9. More than 90% of soils contained less than 0.5 mg kg-1 DTPA-extractable Zn, which is widely considered to be the critical deficiency concentration of Zn for plants grown on calcareous soils. About 25% of soils contained less than 2.5 mg kg-1 DTPA-extractable Fe which is considered to be the critical deficiency concentration of Fe for plants. The concentrations of DTPA-extractable Mn and Cu were in the sufficiency range. Also the Zn concentrations in leaves were very low. More than 80% of the 136 leaf samples contained less than 10 mg Zn kg−1. By contrast, concentrations of Fe, Mn and Cu in leaves were in the sufficient range.In the field experiments at six locations, application of 23 kg Zn ha-1 increased grain yield in all locations. Relative increases in grain yield resulting from Zn application ranged between 5% to 554% with a mean of 43%. Significant increases in grain yield (more than 31%) as a result of Zn application were found for the locations where soils contained less than 0.15 mg kg-1 DTPA-extractable Zn.In pot experirnents with two bread (Triticum aestivum, cvs. Gerek-79 and Kirac-66) and two durum wheats (Triticum durum, cvs. Kiziltan-91 and Kunduru-1149), an application of 10 mg Zn kg-1 soil enhanced shoot dry matter production by about 3.5-fold in soils containing 0.11 mg kg-1 and 0.15 mg kg-1 DTPA-extractable Zn. Results from both field observations and greenhouse experiments showed that durum wheats were more susceptible to Zn deficiency than the bread wheats. On Zn deficient soils, durum wheats as compared to bread wheats developed deficiency symptoms in shoots earlier and to a greater extent, and had lower Zn concentration in shoot tissue and lower Zn content per shoot than the bread wheats.The results presented in this paper demonstrate that (i) Zn deficiency is a critical nutritional problem in Central Anatolia substantially limiting wheat production, (ii) durum wheats possess higher sensitivity to Zn deficient conditions than bread wheats, and (iii) wheat plants grown in calcareous soils containing less than 0.2 mg kg-1 DTPA-extractable Zn significantly respond to soil Zn applications. The results also indicate that low levels of Zn in soils and plant materials (i.e. grains) could be a major contributing factor for widespread occurrence of Zn deficiency in children in Turkey, whose diets are dominated by cereal-based foods.

Effect of different zinc application methods on grain yield and zinc concentration in wheat cultivars grown on zinc‐deficient calcareous soils

Abstract The effect of six different zinc (Zn) application methods on grain yield and concentrations of Zn in whole shoots and grain was studied in wheat cultivars (Triticum aestivum, L. cvs. Gerek‐79, Dagdas‐94 and Bezostaja‐1 and Triticum durum, Desf. cv. Kunduru‐1149) grown on severely Zn‐deficient calcareous soils (DTPA‐extractable Zn: 0.12 mg‐kg‐1 soil) of Central Anatolia which is the major wheat growing area of Turkey. Zinc application methods tested were: a) control (no Zn application), b) soil, c) seed, d) leaf, e) soil+leaf, and f) seed+leaf applications. Irrespective of the method, application of Zn significantly increased grain yield in all cultivars. Compared to the control, increases in grain yield were about 260% with soil, soil+leaf, and seed+leaf, 204% with seed and 124% with leaf application of Zn. In a similar manner, biomass production (dry weight of above‐ground parts) was increased by Zn treatments. The highest increase (109%) was obtained with the soil application and the lowest inc...

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.

Effect of seed zinc content on grain yield and zinc concentration of wheat grown in zinc-deficient calcareous soils

Abstract Field experiments were carried out to study the effect of different seed‐zinc (Zn) content on grain yield and grain Zn concentration in a bread wheat cultivar Atay 85 grown in a severely Zn‐deficient soil under rainfed and irrigated conditions for two years. Three groups of seeds with Zn contents of 355, 800, and 1,465 ng Zn seed‐1 were obtained through different number of foliar applications of ZnSO4.7H2O in the previous crop year. Experiments were carried out with 23 kg Zn ha‐1 (as ZnSO4.7H2O) and without Zn fertilization to the soil. Grain yield from seeds with 800 and 1,465 ng Zn seed‐1 content was significantly higher than that from low seed‐Zn, especially under rainfed conditions. In the first year, under rainfed and Zn‐deficient conditions, yield of plants grown from the highest seed‐Zn content was 116% higher than the yield of plants grown from the low seed‐Zn content. However, in the first year soil‐Zn application combined with low‐Zn seed resulted in a yield increase of 466% compared to...

Morphological and physiological differences in the response of cereals to zinc deficiency

Greenhouse and growth chamber experiments were carried out using seven bread wheat (Triticum aestivum), three durum wheat (T durum), two rye (Secale cereale), three barley (Hordeum vulgare), two triticale (x Triticosecale Wittmack) and one oat (Avena sativa) cultivars to study response to zinc (Zn) deficiency and Zn fertilisation in nutrient solution and in a severely Zn deficient calcareous soil. Visual Zn deficiency symptoms, such as whitish-brown necrotic patches on leaf blades, developed rapidly and severely in the durum wheat and oat cultivars. Bread wheat showed great genotypic differences in sensitivity to Zn deficiency. In triticale and rye, visual deficiency symptoms were either absent or appeared only slightly, while barley showed a moderate sensitivity. When grown in soil, average decreases in shoot dry matter production due to Zn deficiency were 15% for rye, 25% for triticale, 34% for barley, 42% for bread wheat, 63% for oat and 65% for durum wheat. Differential Zn efficiency among and within cereal species was better related to the total amount of Zn per shoot, but not to the Zn concentration in the shoot dry matter. However, in leaves of Zn efficient rye and bread wheat cultivars, the activity of Zn-containing Superoxide dismutase was greater than in Zn inefficient bread and durum wheat cultivars, suggesting higher amounts of physiologically active Zn in leaf tissue of efficient genotypes. When grown in nutrient solution, there was a poor relationship between Zn efficiency and release rate of Zn-chelating phytosiderophores from roots, but uptake of labelled Zn (65Zn) and its translocation to the shoot was higher in the Zn efficient rye and bread wheat cultivars than in inefficient bread and durum wheat cultivars. The results demonstrate that susceptibility of cereals to Zn deficiency decline in the order durum wheat > oat > bread wheat > barley > triticale > rye. The results also show that expression of high Zn efficiency in cereals was causally related to enhanced capability of genotypes to take up Zn from soils and use it efficiently in tissues.

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.

Screening for zinc efficiency among wheat relatives and their utilisation for alien gene transfer

Genetic diversity for micronutrient efficiency among the most highly adapted and advanced hexaploid and tetraploid wheat cultivars in the world is limited compared with alien species of wheat or rye. Therefore, screening for zinc efficiency was conducted in greenhouse experiments under controlled conditions, and in field trials. Different varieties of hexaploid wheat, hexaploid oats and diploid rye, together with hexaploid and octoploid triticales, wheat-Agropyron, wheat-Aegilops and several wheat-alien chromosome addition series were studied. Considerable differences in zinc efficiency were found between wheat and its relatives. Individual chromosomes of Secale, Agropyron and Haynaldia were found to carry major genes for this character. The transfer of alien chromosome segments was effective, demonstrated using several wheat-rye translocation lines. Alien genetic information was clearly expressed in the wheat genetic background. Further experimental introgressions by chromosome manipulation and marker-aided selection may efficiently contribute to wheat improvement in marginal soils.

Effect of Zinc Humate on Growth of Soybean and Wheat in Zinc‐Deficient Calcareous Soil

Abstract Humic acids have many benefits for plant growth and development, and these effects may be maximized if these materials are combined with micronutrient applications. In the present study, pot experiments were conducted to evaluate the effects of zinc (Zn) humate and ZnSO4 on growth of wheat and soybean in a severely Zn‐deficient calcareous soil (DTPA‐Zn: 0.10 mg kg−1 soil). Plants were grown for 24 (wheat) and 28 days (soybean) with 0 or 5 mg kg−1 of Zn as either ZnSO4 or Zn humate. Zinc humate used in the experiments was obtained from Humintech GmbH, Germany, and contained 5% of Zn. When Zn was not supplied, plants rapidly developed visible symptoms of Zn deficiency (e.g., chlorosis and brown patches on young leaves in soybean and necrotic patches on middle‐aged leaves in wheat). Adding Zn humate eliminated Zn‐deficiency symptoms and enhanced dry matter production by 50% in soybean and 120% in wheat. Zinc‐humate and ZnSO4 were similarly effective in increasing dry matter production in wheat; but Zn humate increased soybean dry matter more than ZnSO4. When Zn was not supplied, Zn concentrations were 6 mg kg−1 for wheat and 8 mg kg−1 for soybean. Application of Zn humate and ZnSO4 increased shoot Zn concentration of plants to 36 and 34 mg kg−1 in wheat and to 13 and 18 mg kg−1 in soybean, respectively. The results indicate that soybean and wheat plants can efficiently utilize Zn chelated to humic acid in calcareous soils, and this utilization is comparable to the utilization of Zn from ZnSO4. Under Zn‐deficient soil conditions, plant growth and yield can be maximized by the combined positive effects of Zn and humic acids.

Differences in Shoot Boron Concentrations, Leaf Symptoms, and Yield of Turkish Barley Cultivars Grown on Boron‐Toxic Soil in Field

Abstract Using 10 barley Turkish cultivars (Hordeum vulgare L.) field experiments were carried out on soils containing normal and very high soluble boron (B) concentration to study genotypic variation in tolerance to B toxicity in soil and the relationships between the shoot or leaf concentrations of B, severity of B‐toxicity symptoms and yield. As judged by differences in degree of severity of B‐toxicity symptoms on leaves and in reduction of shoot dry weight or grain yield there was a substantial genotypic variation in tolerance to B toxicity in soil. Among the barley cultivars examined Hamidiye and Bülbül were the most sensitive, and Anadolu and Tarm‐92 the most tolerant. The differences in tolerance to B toxicity showed a very close relationship to the severity of B‐toxicity symptoms, but not at all to shoot or leaf concentrations of B. Despite the distinct differences in sensitivity to B toxicity, B‐tolerant, and B‐sensitive cultivars had very similar tissue concentrations of B, and even the most B‐sensitive cultivar, Hamidiye contained the lowest B concentration in flag leaves. Shoot dry weight of the cultivars at the tillering stage corresponded well to the grain yields. These results suggested that the symptom scoring for B toxicity symptoms and shoot dry weight at early stage of growth can be considered as reliable criteria for screening cultivars for tolerance to B toxicity in soils. In view of the results obtained in the present study one may speculate that internal mechanisms play a decisive role in expression of differential tolerance to B toxicity in field‐grown barley cultivars.