Effect of Zn application on its uptake,distribution and concentration of Fe and Cu in finger millet [Eleusine coracana (L.) Gaertn.]

Zinc (Zn) malnutrition can be alleviated by increasing the dietary Zn intake through Zn biofortification of edible crops. Agronomic and genetic biofortification has been suggested as better option to increase the dietary Zn. In this study, we show considerable genetic variability for seed Zn concentration in six leading finger millet genotypes. External application of Zn resulted in improved Zn concentration in different plant parts; in particular there was significant increase in seed Zn concentration in all genotypes. Though genotypes GPU28 and INDAF5 showed differences in root and shoot Zn at vegetative stage but at reproductive stage there was no significant difference. Apart from that, Zn application increased the seed iron (Fe) concentration with no or minimal effect on copper (Cu) concentration.     

Using arbuscular mycorrhiza to alleviate the stress of soil compaction on wheat (Triticum aestivum L.) growth

Since large areas of agricultural fields in the world become compacted every year, much effort has been made to reduce the adverse effects of soil compaction on plant growth. Mechanical methods to control soil compaction may be laborious and expensive; however, biological methods such as using arbuscular mycorrhiza (AM) may be more useful, economically and environmentally. The objectives of this study were: (1) to evaluate the effects of soil compaction on wheat (Triticum aestivum L.) growth, and (2) to evaluate if using AM of different origin can reduce the stressful effects of soil compaction on wheat growth. Unsterilized and sterilized soils, different levels of compaction and three species of arbuscular mycorrhiza were applied in four replicates. The experiments were conducted in the Soil and Water Research Institute, Karaj, Iran. Soil physical and chemical properties were determined. The AM increased wheat growth in both soils at different levels of soil compaction in both experiments. For root, shoot (P=0.1) and grain (P=0.05) dry weights increases were significant. AM enhanced root growth more than shoot growth under compaction (AM resulted in significant increase in root/shoot ratios, P=0.1). Due to its unique characteristics, AM may reduce the stressful effects of soil compaction on wheat growth, though its effectiveness may decrease with increasing compaction.     

Effects of ZnSO4 and Zn‐EDTA applied by broadcasting or by banding on soil Zn fractions and Zn uptake by wheat (Triticum aestivum L.) under greenhouse conditions

Zinc biofortification of staple food crops is essential for alleviating worldwide human malnutrition. Agronomic interventions to promote this should include fertilizer selection and management. A chelated Zn source, Zn‐EDTA, and an inorganic Zn source, ZnSO₄ × 7 H₂O, were applied either by banding or by broadcasting in soil, and Zn fractions in soil and Zn uptake by wheat were determined in a pot experiment. Compared to ZnSO₄ × 7 H₂O, Zn‐EDTA produced higher Zn concentration in grain regardless of application method and even at a lower application rate. Residual Zn fraction was the largest Zn fraction with both ZnSO₄ and Zn‐EDTA amendment. ZnSO₄ banded in soil caused Zn fractions to be restricted to the Zn‐amended soil band and resulted in lower grain Zn concentrations than did broadcast ZnSO₄. Planting wheat slowed Zn fixation by promoting the maintenance of a high concentration of Zn fraction loosely bound to organic matter (LOM‐Zn) in soil. Zn‐EDTA was a better Zn source for Zn biofortification of wheat than was ZnSO₄.     

Effect of intercropping on crop yield and chemical and microbiological properties in rhizosphere of wheat (Triticum aestivum L.), maize (Zea mays L.), and faba bean (Vicia faba L.)

In this study, we investigated crop yield and various chemical and microbiological properties in rhizosphere of wheat, maize, and faba bean grown in the field solely and intercropped (wheat/faba bean, wheat/maize, and maize/faba bean) in the second and third year after establishment of the cropping systems. In both years, intercropping increased crop yield, changed N and P availability, and affected the microbiological properties in rhizosphere of the three species compared to sole cropping. Generally, intercropping increased microbial biomass C, N, and P availability, whereas it reduced microbial biomass N in rhizosphere of wheat. The rhizosphere bacterial community composition was studied by denaturing gradient gel electrophoresis of 16S rRNA. In the third year of different cropping systems, intercropping significantly changed bacterial community composition in rhizosphere compared with sole cropping, and the effects were most pronounced in the wheat/faba bean intercropping system. The effects were less pronounced in the second year. The results show that intercropping has significant effects on microbiological and chemical properties in the rhizosphere, which may contribute to the yield enhancement by intercropping.     

水培和土培条件下氮素供应对燕麦生长和磷素吸收的影响

Plants show different growth responses to N sources supplied with either NH₄⁺ or NO₃^-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavailability of soil phosphorus, particularly in alkaline soils. The plant growth, P uptake, and P availability in the rhizosphere of oat (Avena nuda L.) grown in hydroponics and in soil culture were investigated under supply with sole NH₄⁺-N, sole NO₃^--N, or a combination. Sole NO₃^--fed oat plants accumulated more biomass than sole NH₄⁺-fed ones. The highest biomass accumulation was observed when N was suppliedw ith both NH₄⁺-N and NO₃^--N. Growth of the plant root increased with the proportion of NO₃^- in the cultural medium. Better root growth and higher root/shoot ratio were consistently observed in NO₃^--fed plants. However, root vigor was the highest when N was supplied with NO₃^-+NH₄⁺. NH₄⁺ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO₄ added as P source. No P deficiency was observed, and plant P concentrations were generally above 2 g kg^-1. P uptake was increased when N was supplied partly or solely as NO₃^--N, similarly as biomass accumulation. The results suggested that oat was an NO₃^--preferring plant, and NO₃^--N was essential for plant growth and the maintenance of root absorption capacity. N supply with NH₄⁺-N did not improve P nutrition, which was most likely due to the absence of P deficiency.