Application Of Zn Fertilizers Research Articles

Mitigating zinc deficiency through integration of agronomic biofortification for achieving high zinc wheat grain in northern states of India

Twenty-five field experiments on wheat as test crop were conducted across four northern states of India viz., Uttar Pradesh, Punjab, Haryana and Himachal Pradesh during 2014–15 and 2015–16 to investigate the effect of soil and foliar applications of zinc (Zn) on wheat grain yield and grain Zn concentration. Experimental design was complete randomized block design with three replicates. Wheat crop was grown under three different Zn application rates as follows: (i) Control (no Zn application), (ii) Soil Zn application, and (iii) Foliar Zn application. The soil Zn treatment consisted of 50 kg ZnSO4.7H2O ha applied to the soil before sowing of wheat. The foliar Zn treatment, a 0.5% (w/v) aqueous solution of ZnSO4.7H2O was realized two times i. e. first at anthesis or heading and the second one at early milk stage of wheat crop. Results showed that the application of Zn fertilizer in soil increased grain yield of wheat significantly over control at 23 locations during both the years. However, the effect of foliar Zn fertilizer on grain yield was quite less effective. The foliar Zn application resulted in significant increment in grain Zn concentration over control at all locations. In particular, soil Zn application markedly increased grain yield and slightly less content of grain Zn over foliar Zn application. However, foliar application of Zn at specific stages was an important agronomic practice for the farmers to enhance wheat grains with zinc to mitigate hidden hunger. In conclusion, agronomic biofortification was found to be most suitable for both optimum grain yield and grain biofortification of wheat to combat Zn deficiency.

Agronomic biofortification of wheat grains with zinc through different modes of zinc fertilization

Thirty field experiments were conducted during rabi seasons of 2014–15 and 201516 across farmers’ fields of four villages of district Faridabad, Haryana, India using wheat as test crop to evaluate the effects of soil and foliar mode of application of zinc fertilizer on grain yield and Zn concentration. The application of Zn fertilizer in soil increased grain yield of wheat significantly over control at few locations during both the years where low Zn soils existed i. e. from 3.9 to 12.6% and 3.3 to 10.5% during 2014–15 and 2015–16, respectively, over no soil Zn addition. However, foliar treatment of Zn fertilizer on grain yield was quiet less effective. The foliar Zn application resulted in significant increases in grain Zn content over control at all locations. Maximum increase in grain Zn concentration with foliar spray of Zn was 125.73 and 122.82% higher during 2014–15 and 2015–16, respectively, over control. It was found that foliar application of Zn is an important agronomic practice for the farmers to enrich wheat grains with zinc. Increasing grain yield by soil application and grain Zn concentration by foliar application of zinc fertilizer also provides additional positive impacts in terms of economic benefits and to secure nutritional quality and mitigate hidden hunger.

Soil application of zinc fertilizer could achieve high yield and high grain zinc concentration in maize

Increasing both yield and grain zinc (Zn) concentration (GZC) are the two important goals of maize production in China and elsewhere in the world. However, it is not clear whether soil application of Zn fertilizer could realize high yield and GZC. The current study aimed to examine how soil Zn application affects yield and GZC and what is the optimal DTPA-Zn for high yield and GZC requirement. A 3-year field experiment with Zn fertilizer application rates of 0, 10, 25, 50, 100, 150 kg ZnSO4•7H2O ha−1 was conducted. Soil Zn application significantly increased soil DTPA-Zn concentrations, maize yield, GZC and kernels number per spike; and decreased the length of barren ear tips. In each of these cases, the level of response was highly related to the quantity of Zn added to soil. The optimal soil DTPA-Zn concentration was 4.7 mg kg−1 required to attain high yields and was 7.6 mg kg−1 required to attain high GZC, respectively. Soil Zn fertilization can increase simultaneously both grain yield and GZC and achieved the biofortification of maize with Zn, and its realization depended on the available Zn concentrations in soil.

Biofortification of wheat, rice and common bean by applying foliar zinc fertilizer along with pesticides in seven countries

Rice (Oryza sativa L.), wheat (Triticum aestivum L.) and common bean (Phaseolus vulgaris L.) are major staple food crops consumed worldwide. Zinc (Zn) deficiency represents a common micronutrient deficiency in human populations, especially in regions of the world where staple food crops are the main source of daily calorie intake. Foliar application of Zn fertilizer has been shown to be effective for enriching food crop grains with Zn to desirable amounts for human nutrition. For promoting adoption of this practice by growers, it is important to know whether foliar Zn fertilizers can be applied along with pesticides to wheat, rice and also common bean grown across different soil and environmental conditions. The feasibility of foliar application of zinc sulphate (ZnSO4.7H2O) to wheat, rice and common bean in combination with commonly used five fungicides and nine insecticides was investigated under field conditions at the 31 sites-years of seven countries, i.e., China, India, Pakistan, Thailand, Turkey, Brazil and Zambia. Significant increases in grain yields were observed with foliar Zn/foliar Zn + pesticide (5.2–7.7 % of wheat and 1.6–4.2 % of rice) over yields with no Zn treatment. In wheat, as average of all experiments, higher grain Zn concentrations were recorded with foliar Zn alone (41.2 mg kg−1) and foliar Zn + pesticide (38.4 mg kg−1) as compared to no Zn treatment (28.0 mg kg−1). Though the magnitude of grain Zn enrichment was lesser in rice than wheat, grain Zn concentrations in brown rice were significantly higher with foliar Zn (24.1 mg kg−1) and foliar Zn + pesticide (23.6 mg kg−1) than with no Zn (19.1 mg kg−1). In case of common bean, grain Zn concentration increased from 68 to 78 mg kg−1 with foliar Zn alone and to 77 mg kg−1 with foliar Zn applied in combination with pesticides. Thus, grain Zn enrichment with foliar Zn, without or with pesticides, was almost similar in all the tested crops. The results obtained at the 31 experimental site-years of seven countries revealed that foliar Zn fertilization can be realized in combination with commonly-applied pesticides to contribute Zn biofortification of grains in wheat, rice and common bean. This agronomic approach represents a useful practice for the farmers to alleviate Zn deficiency problem in human populations.

Agronomic Bio-fortification of Zinc in Indigenous, High Yielding and Hybrid Rice (Oryza sativaL.) Cultivars

Field experiment was conducted to assess the Zn content of rice grain and straw with and without Zn fertilizer application in a red and lateritic soil of Ranchi (Jharkhand). While, the grain yield of hybrid rice was considerably higher as compared to high yielding and indigenous rice cultivars, the response to added Zn in rice was not significant. Highest content of Zn (37.1 mg kg-1) was recorded in rice grain of indigenous rice cultivars, when Zn was applied @ 100 kg ha-1 of ZnSO4.7H2O (soil application) + 3 foliar application of 0.5% ZnSO4.7H2O. Results suggested that indigenous and high yielding rice cultivars were more suited than hybrids in red and lateritic soil for agronomic bio-fortification. Content of Zn in rice grain of indigenous cultivars was higher (32.1 mg kg-1) followed by HYV (26.7 mg kg-1) and hybrid (24.1 mg kg-1) cultivars of rice. Total Zn removal by rice crop was 0.44, 0.65 and 0.63 kg ha-1, respectively when indigenous; HYV and hybrid rice cultivars were grown without any addition of Zn. Soil as well as soil + foliar application of Zn increased the Zn uptake by rice more than two times, compared to its non-application. Apparent Zn recovery in rice was low i.e. 1.99, 1.49 and 1.08 per cent only with soil application of 100 kg ha-1 of ZnSO4.7H2O, respectively by hybrid, HYV and indigenous rice cultivars. This was considerably higher i.e. 4.32% in hybrid, 3.19% in HYV and 2.53% in indigenous rice cultivars, when Zn was added through soil (100 kg ha-1 of ZnSO4.7H2O) + foliar application of 0.5% ZnSO4.7H2O.

Effects of zinc fertilizer rate and application method on photosynthetic characteristics and grain yield of summer maize

Zinc deficiency is a worldwide nutritional constraint for crop production in many types of soil, particularly in cereals growing in calcareous soil. Two field trials were conducted to study the effects of zinc fertilizer doses and application method on photosynthetic characteristics and grain yield of summer maize, from June to September of 2013, in Xun County (34o40,12” N, 114o32,24”E) and Yuzhou County (33o59,19”N, 113o33,47”E). Optimal Zn fertilizer application (30 kgZnSO4·7H2O hm-2) increased chlorophyll content in leaves, improved photosynthesis, and increased grain yield of summer maize. At 15 kg ZnSO4·7H2O hm-2, grain yield was higher in Xun County and lower in Yuzhou County when the entire amount was applied as basal fertilization as opposed to being split between the basal and foliar fertilization. The opposite result (grain yield lower in Xun County than in Yuzhou County) was obtained at 30 kg ZnSO4·7H2O hm-2. These results have important implications for guiding the rational application of Zn fertilizer and improving the grain yield of summer maize in Henan province.

Improving key enzyme activities and quality of rice under various methods of zinc application

Zinc (Zn) is an important micronutrient for the physiology of plants. It is poorly available to the plants in soil solution. A pot experiment was conducted to evaluate effectiveness of various Zn application methods on key enzyme activities and protein content of two contrasting rice genotypes viz., PD16 (Zn efficient) and NDR359 (Zn inefficient). The treatments were, control (0 mg Zn kg(-1)soil), soil application (5mg Zn kg(-1) soil), foliar application (0.5% ZnSO4 + 0.25% lime at 30, 60 and 90days after transplanting), soil (5mg Zn kg(-1) soil) + foliar application of 0.5% ZnSO4 + 0.25% lime at 30, 60 and 90days after transplanting. Among all the methods tested soil+foliar application of Zn fertilizers was found most effective in increasing superoxide dismutase (SOD) and carbonic anhydrase (CA) activitiesas well as chlorophyll and protein content in both the rice varieties. NDR359, showed higher enzyme activities and more chlorophyll content in leaves than PD16, when Zn was appliedeither through foliar spray alone or in soil along with foliar application. Regarding the protein content in grains, PD16 showed higher protein content than NDR359, thus showed better translocation of Zn from leaves to grains.

Zinc fertilization of lentil for grain yield and grain zinc concentration in ten Saskatchewan soils

ABSTRACTFertilization of grain legumes with zinc (Zn) can affect both marketable yield and Zn content of the grain, which is important in addressing human nutritional deficiencies in certain regions of the world. A pot experiment was conducted to determine the response of three different market classes of lentil to Zn fertilization using ten surface soils from Saskatchewan (Canada). The distribution of Zn among labile and stable fractions chemically separated from the soil was also determined in the ten prairie soils and related to the lentil responses observed. The three market classes of lentils (large and small green, small red) were grown without Zn (control), and with 2.5 and 5 kg Zn ha−1 added as zinc sulfate to each soil prior to planting. Zinc fertilizer application significantly influenced grain yield and was soil dependent. A significant increase in grain yield over the control was observed from application of Zn on some low organic matter, high pH Brown Chernozem soils whereas a decrease in grain yield over control was observed in other soils such as a Black Chernozem of high organic matter content and low (<7) pH. Lack of positive yield response to addition of Zn were related to measured high diethylene triamine pentaacetic acid (DTPA) extractable and plant root simulator (PRS) resin membrane probe Zn, and large amounts of native Zn in exchangeable and iron/manganese (Fe/Mn) oxide bound fractions. Application of Zn fertilizer generally increased the grain concentration of Zn. For example, an increase of ∼20% in Zn concentration over control was observed when 5 kg Zn ha−1 was added to a loamy textured low organic matter Brown Chernozem soil. Overall, small green lentil was more consistent in producing a positive response to Zn fertilizer application on soils with low plant available Zn compared to large green lentil and small red lentil.

An effective strategy to improve grain zinc concentration of winter wheat, Aphids prevention and farmers’ income

Foliar zinc (Zn) application represents an effective way to improve grain Zn concentration of cereal crops. Spraying Zn together insecticides would be an important advantage for the growers to minimize costs. However, there is very little information about combined foliar application of Zn fertilizers together with insecticides. A field experiment was conducted to investigate how spraying Zn fertilizer in form of ZnSO4 together with commonly applied insecticides (e.g., Acetamiprid and Imidacloprid) affects the grain Zn concentration of wheat grown in the Northern China Plain. The main treatment included three levels: only insecticide applied (recorded as T1); foliar Zn fertilizer applied one day after insecticide application (recorded as T2); foliar Zn fertilizer applied together with insecticide (recorded as T3). The results showed that there was no antagonistic effect between insecticide and Zn when they were sprayed together. Compared with insecticide application only, foliar application of Zn fertilizer with insecticide increased grain yield by 3.7–4.9%, and grain Zn density by 48.2–61.6%. Grain yield and grain Zn concentration were not affected no matter Zn fertilizers were applied simultaneously with insecticide or one day after. The toxic effect of insecticide on insects was not affected when it was mixed with Zn fertilizer in the laboratory condition. Compared with application of Zn fertilizer and insecticide at different times, simultaneous combination can reduce the cost by 120 USDha−1 and increase farmers’ net income by 6.3%. Therefore the results show clearly that ZnSO4 can be mixed and sprayed together with insecticide without causing any adverse effect. This is a very useful and cost-effective approach for growers contributing both to improving grain yield and grain Zn concentration and controlling aphids as well.

Agronomic fortification of rice and wheat grains with zinc for nutritional security

Zinc (Zn) deficiency is the most widespread micronutrient deficiency in crop plants and humans. Low intake of Zn through diet appears to be the major reason for the widespread prevalence of Zn deficiencies in human populations. Application of Zn fertilizer in soil having low Zn increased the grain yield in wheat up to 6.4-50.1%. However, soil Zn application increased the grain yield of rice only up to 7.2-14.8%. Soil having sufficient Zn had no or little effect on grain yield with soil Zn application. The application of foliar Zn with or without propiconazole resulted in significant increases in grain Zn irrespective of soil Zn status. Application of foliar Zn along with propiconazole at earing and milk stages proved beneficial in increasing grain Zn content in both rice and wheat. Hence agronomic biofortification is possible and could be considerably economical if used along with a fungicide depending upon appearance of a disease.

Effects of soil zinc availability, nitrogen fertilizer rate and zinc fertilizer application method on zinc biofortification of rice

SUMMARYRice (Oryza sativa L.) is one of the most important cereal crops in the world and a potentially important source of zinc (Zn) in the diet. The improvement of Zn content of rice is a global challenge with implications for both rice production and human health. The objective of the present study was to identify the effects of nitrogen (N) fertilizer rates and Zn application methods on Zn content of rice by evaluating rice production on native soils with different Zn availabilities in 2010/11. The results indicated that Zn application increased rice grain yield and Zn content in grains compared with the control; however, this effect was also affected by the native soil Zn availability, N fertilizer rate and Zn fertilizer application method. The native soil Zn status was the dominant factor influencing grain yield and grain Zn content in response to Zn fertilizer application. Grain Zn content ranged from 19·74 to 26·93 mg/kg under the different Zn statuses. The results also indicated that Zn application method has a significant influence on grain yield. Application of Zn fertilizer to the soil was more effective than the foliar spray on rice grain yield; however, the foliar spray resulted in a greater increase in grain Zn content when compared with soil application. Grain Zn content was affected by application method and displayed the following general trend: soil application + foliar spray &gt; foliar spray &gt; soil application. The experiments investigating the effect of N fertilizer rate combined with Zn application method showed a clear increase in both grain yield and Zn content as the N fertilizer level increased from 200 to 300 kg/ha. In addition, the results also indicated that N content and accumulation increased in all plant tissues, which suggests that Zn application might influence the uptake and translocation of N in rice plants. These results suggest that soil application in addition to a foliar spray of Zn should be considered as an important strategy to increase grain yield and grain Zn content of rice grown in soils with low background levels of Zn-associated diethylene triamine pentaacetate acid. Moreover, this process could be further strengthened by a high N application rate. In conclusion, these results demonstrate the potential of optimizing nutrient management using Zn fertilizer to obtain higher grain yields and higher grain Zn content in fields with low native Zn status.

Exploring the Role of Zinc in Maize (Zea Mays L.) through Soil and Foliar Application

Maize (Zea mays L.) is considered as high nutrient demanding crop and needs balanced nutrition. It is also regarded sensitive to zinc deficiency. Zinc is mostly deficient in soils and application of zinc fertilizer is required to explore its full potential. Crop species and even cultivars within species vary in their Zn requirement. A field experiment was conducted during spring 2011 at Agronomic Research Area, University of Agriculture, Faisalabad, Pakistan to evaluate the comparative efficacy of Zn uptake and grain yield in three maize hybrids (Pioneer-32 F 10, Monsanto-6525 and Hycorn-8288) through the application of Zn in the form of ZnSO4. The ZnSO4 treatments comprised; soil application at the time of sowing @ 12 kg ha-1, foliar application at vegetative stage (9 leaf stage) @ 1% ZnSO4 solution and foliar application at reproductive stage (anthesis) @ 1% ZnSO4 solution and one treatment was kept as a control. The experimental results showed substantial difference in yield and yield contributing parameters such as plant population at harvest, number of grains per cob, biological yield, grain yield and harvest index. Statistically maximum grain yield (8.76t ha-1) was obtained with foliar spray of ZnSO4 at 9-leaf stage (Zn2) in case of Monsanto-6525. Foliar spray of ZnSO4 increased 38% and soil application gave 23.7% more grain yield than control treatment. Foliar spray of ZnSO4 at 9-leaf stage in Monsanto-6525 hybrid produced higher grain yield and net field benefit. Thus foliar application of Zn fertilizers has a positive effect on economic and biological yield of maize crop.

Zinc fractionation of tropical paddy soils and their relationships with selected soil properties

Knowledge of zinc (Zn) distribution among various fractions will help to predict the potential of the soil to supply sufficient Zn for crop production. The present study was done to investigate Zn fractions, Zn availability factor (AF) and their relationship with soil properties of Zn-deficient tropical paddy soils. The samples of two soil orders (six soil series) were sequentially extracted with chemical extractants in two different growth stages of rice (maximum tillering and flowering stages). The proportion of Zn fractions extracted at the maximum tillering stage followed the order, water soluble plus exchangeable (WE) < crystalline sesquioxide (Cry) < manganese oxide (MN) < organically bound (Org) < amorphous sesquioxide (Amor) < residual Zn (Res), whereas the order at the flowering stage was as follows: WE < Mn < Cry < Org < Amor < Res. Cation exchange capacity (CEC), clay content and organic carbon (OC) were the most important factors controlling the distribution of Zn in soils. The AF was low in Tok Young (1.79%), high in Telemong (17%) and medium in the rest of soil series (around 8%). A stepwise multiple linear regression and principal component analyses showed that OC, clay content and CEC were the main variables that explained the predictability of Zn fractions. The result of the length of submerging showed that the WE, Org and Cry concentrations decreased, while Amor, MN, and the sum of all Zn fractions increased with increase in the flooding period. The extractability and solid-phase fractionation of Zn in two different times of soil sampling showed the importance of timing of Zn fertilizer application and flooding or pre-flooding in Zn availability.

Yield and Zinc, Copper, Manganese and Iron Concentration in Maize (Zea mays L.) Grown on Vertisol as Influenced by Zinc Application from Various Zinc Fertilizers

Zinc (Zn) deficiency in soils and field crops is widespread across the world, including India, resulting in severe reduction in yield. Hence, soil application of Zn fertilizers is recommended for ameliorating Zn deficiency in soil and for obtaining higher crop yield and better crop quality. Zinc sulfate is commonly used Zn fertilizer in India because of its solubility and less cost. However, good quality and adequate quantity of zinc sulfate is not available in the market round the year for farmers' use. Field experiments were therefore conducted during rainy season of 2010 and 2011 at research farm of Indian Institute of Soil Science, Bhopal, India to assess the influence of Zn application through zinc sulfate monohydrate (33% Zn), zinc polyphosphate (21% Zn) and Zn ethylenediaminetetraacetate (EDTA) (12% Zn) on yield and micronutrient concentration and uptake by maize (Zea mays L.). In both the years, grain and vegetative tissue (stover) yield of maize increased significantly with successive application of Zn up to 1 kg ha−1 added through zinc sulfate monohydrate and zinc polyphosphate. Addition of 2.5 kg Zn ha−1 did not increase yield further but resulted in highest stover Zn concentration. Zinc, copper (Cu), manganese (Mn), and iron (Fe) concentration in maize grain varied from 22.2 to 27.6, 1.6 to 2.5, 3.5 to 4.7 and 19.9 to 24.5 mg kg−1 respectively in both the years. Maize stover had 25.9 to 36.2, 7.9 to 9.8, 36.7 to 44.9 and 174 to 212 mg kg−1 Zn, Cu, Mn, and Fe, respectively. Zinc application did not influence Cu, Mn and Fe concentration in both grain and stover of maize. Transfer coefficients (TCs) of micronutrients varied from 0.72 to 0.95, 0.18 to 0.30, 0.08 to 0.13 and 0.10 to 0.15 for Zn, Cu, Mn, and Fe respectively. Total Zn uptake significantly increased with Zn application from 0.5 to 2.5 kg ha−1 supplied through zinc sulfate monohydrate and zinc polyphosphate. Recovery efficiency of Zn declined with increased Zn rates.

Effects of Iron and Zinc Fertilizers on the Accumulation of Fe And Zn Ions in Potato Tubers

The aim of this study was the evaluation of the methods to increase the yield of potato and the accumulation of iron (Fe) and zinc (Zn) in response to iron and zinc fertilizers. In these studies, ‘Marfona’ potato (Solanum tuberosum) cultivar was used in a statistical factorial design experiment with three factors: methods of fertilizer application (2 levels of spray and one level by irrigation), kind of fertilizers (iron and zinc) and levels of fertilizer, (0, 1, 2, and 3 mg L−1). Results showed that iron and zinc fertilizers increased the tubers weight and the tubers number weight−1 ratio (P < 0.01). Also, results showed that the effects of Fe and Zn fertilizers application in irrigation water was more significant (P < 0.01) than by spray application. In addition, application of Fe and Zn fertilizers resulted in higher concentrations of these ions in the harvested tubers improving their nutritional values.

Different Forms of Soil Zinc - their Relationship with Selected Soil Properties and Contribution towards Plant Availability and Uptake in Maize Growing Soils of Erode District, Tamil Nadu

Information on soil zinc (Zn) distribution is essential for understanding its chemical reactions and bioavailability. A study was conducted on the distribution of different forms of soil Zn and response of maize to native soil Zn content at four locations (L1, L2, L3 and L4) having very low, low, medium and high soil available Zn status. The results revealed that various chemical pools of Zn under incubation condition treated with graded levels of Zn fertilizer application (0, 1.25, 2.50, 5.0, 7.5, 10.0 Zn as ZnSO4 kg ha-1) showed significant variation in almost all the locations and similar trends were noticed for all the soil studied, where the highest amount of added Zn (10 kg Zn ha-1) always produced greater Zn release than the lower doses. Among the fractions, the higher release of water soluble plus exchangeable zinc (WSEX-Zn), organically bound zinc (OM- Zn) and crystalline bound zinc (CFeOX-Zn) were observed at 15 days after incubation(DAI) and gradually declined at the end of the experiment upto 30DAI whereas other forms such as manganese oxide bound zinc (MNOX- Zn), amorphous sesquioxide bound zinc (AFeOX- Zn), residual zinc (RES- Zn) and TOTAL- Zn showed a prolonged release upto 30 DAI. Also from the study it is evident that the content of different fractions varied between the soils of all locations, the order of preponderance of different zinc fractions viz. WS and EX < OM < AFe-OX < CFe-OX) < MN-OX < RES and it remained same for all the locations. More than 95 % of the total Zn content occurred in the relatively inactive and mineral-bound residual form (RES), whereas only a small fraction occurred in WS and EX, OM, AFe-OX, and CFe-OX fractions. The pot culture experiment conducted with similar set of treatments with maize crop responded well to Zn fertilizer application and the location with very low Zn status with 7.50 kg Zn ha-1 showed higher value for the dry matter production (76.4 g plant- 1) and Zn - uptake (3.34 mg plant-1). Correlation data indicated that those fractions are in a state of dynamic equilibrium among different fractions and were influenced by pH, EC, CEC, organic carbon, DTPA- Zn and also revealed that almost all the fractions contributed to the plant availability. In all the cases it is noted that the release of various forms of Zn and response of maize crop to Zn fertilizer application always higher for the soil having very low Zn followed by low, medium and high Zn status.

Wheat plants invest more in mycorrhizae and receive more benefits from them under adverse than favorable soil conditions

Soil chemistry and biota heavily influence crop plant growth and mineral nutrition. The stress-severity and optimal resource allocation hypotheses predict mutualistic symbiotic benefits to increase with the degree of metabolic imbalance and environmental stress. Using two cross-factorial pot experiments with the same biologically active calcareous soil, one time highly saline and nutrient-deficient, and the other time partially desalinated and amended with mineral soil fertilizer, we explored whether these general predictions hold true for zinc (Zn) nutrition of bread wheat in mycorrhizal symbiosis. Increased arbuscular mycorrhizal (AM) fungal root colonization positively correlated with plant Zn nutrition, but only when plants were impaired in growth due to salinity and nutrient-deficiency; this was particularly so in a cultivar-responsive to application of mineral Zn fertilizer. Evidence for direct involvement of AM fungi were positive correlations between Zn uptake from soil and frequency of fungal symbiotic nutrient exchange organelles, as well as the quantitative abundance of AM fungi of the genera Funneliformis and Rhizophagus, but not Claroideoglomus. Combined partial soil desalination and fertilization swapped the dominance ranking from Claroideoglomus spp. to Funneliformis spp. Positive growth, nitrogen, and Zn uptake responses to mycorrhization were contingent on moderate soil fertilization with ZnSO4. In agreement with the predictions of the stress-severity and optimal resource allocation hypotheses, plants limited in growth due to chemically adverse soil conditions invested relatively more into AM fungi, as evident from heavier root colonization, and took up relatively more Zn and nitrogen in response to mycorrhization, than better growing and less mycorrhized plants. It thus appears that crop plant cultivar-dependent mycorrhization and Zn fertilizer-responsiveness may reinforce each other, provided that there is bioavailable Zn in soil and plant growth is impaired by suboptimal chemical soil conditions.

Winter Oilseed Rape Productivity and Nutritional Quality Responses to Zinc Fertilization

Soil Zn is always potentially deficient in Yangtze River Basin (YRB) of China, due to widespread alkaline soils, high soil P, and large Zn removal of high‐yielding oilseed rape (Brassica napus L.) and rice (Oryza sativa L.) cultivars. However, Zn fertilizer response of winter oilseed rape in YRB is not clear. Therefore, on‐farm experiments were conducted at six locations to investigate the effects of experimental sites and Zn rates (0 and 6.8 kg Zn ha−1) on plant growth, seed yield and quality, and Zn uptake of oilseed rape (Huashuang no. 5 cultivar). Across all the sites, Zn application increased seed yield by 5.0 to 16.0%, oil yield by 6.2 to 19.5%, and protein yield by 2.3 to 17.7%. Application of Zn fertilizer increased the concentrations of total oil, oleic acid, and linoleic acid in rapeseed, but reduced stearic acid concentration. No differences were observed on protein and linolenic acid concentrations between Zn rates. Total Zn uptake in plants increased by 13.5 to 62.3% with Zn fertilizer applied, while Zn harvest index reduced by 3.4 to 18.5%. Oilseed rape performance varied among sites. The extensive significant Zn × site interactions indicated that Zn response was dependent on the environments we studied. Thus, Zn fertilizer management will probably need to be adjusted at different sites. Our results suggested to apply Zn fertilizer to improve oilseed rape productivity, nutritional quality, and Zn uptake. This study also increased the understanding of the positive effects of Zn on rapeseed oil content and fatty acids composition.

Effects of Zinc Sulphate and Monocalcium Phosphate Fertilizers on Extractable Zn and Fe under Different Soil Moisture Conditions

ABSTRACT- To evaluate effects of different soil moisture conditions namely, phosphorus (P) and zinc (Zn) application, on extractable Zn and Fe, two experiments were conducted in laboratory conditions based on a completely randomized design with a factorial arrangement of treatments with two replications. The first experiment was performed with the following factors; incubation time at four levels (1, 10, 30 and 60 days), soil moisture at two levels (0.6 FC and FC), P fertilizer at two levels (0 and 60 mg P per kg of soil) and Zn fertilizer at two levels (0, and 20 mg Zn per kg of soil). The second experiment was conducted with two Zn levels (0 and 20 mg Zn per kg of soil), two P levels (0 and 60 mg P per kg of soil) and three wetting-drying cycles (1, 10 and 20 cycles). The results showed that the extractable Zn and Fe decreased by time. The application of Zn fertilizer under FC conditions resulted in higher amounts of extractable Zn in all incubation times. The application of P reduced the extractable Zn and Fe in most incubation times and moisture conditions. By increasing the number of wetting-drying cycles and the duration of incubation time, the extractable Zn decreased significantly. There were no significant differences between constant moisture and wetting-drying cycles on the extractable Zn, except for the application of 60 mg P and 20 mg Zn per kg of soil under 0.6 FC conditions.

Agronomic Aspects of Zinc Biofortification in Rice (Oryza sativa L.)

Globally, 2.7 billion people suffer from Zn deficiency (ZnD) and 1/3 of the world population living in the poor countries is at the high risk of this deficiency. A staggering number of ZnD deaths occur in South Asia alone. Though the causes of malnutrition are many and complex, one such cause is the dysfunctional food system which is dependent on agriculture. Rice is a staple food for 1/2–2/3 of the world’s population and is mainly (90 %) grown in south, southeast and east-Asia. Nearly 50 % of the Indian soil contains inadequate Zn levels and this ZnD in rice–wheat system affects 50 % of rice, particularly, grown under lowland conditions. In order to address the ZnD issue in rice, various agronomic approaches of Zn biofortification can be tested, i.e., selection of cultivars, rate and time of Zn fertilizer application, crop rotation and use of soil microorganisms. Agronomic Zn biofortification is a promising and cost effective method to increase Zn concentration in rice grains. Thus it can save the life of millions of people in Asia, particularly in India. The present article is a modest attempt to analyze the viability of agronomic biofortification in rice grains as a short term and profitable tool to promote Zn concentration that would consequently cure several health hazards commonly visible among humans in the developing countries.