Combining P and Zn fertilization to enhance yield and grain quality in maize grown on Mediterranean soils.

The main aim of this study was to elucidate the effect of individual and joint fertilization with P and Zn on maize plants grown on typical Mediterranean soils with a limited Zn availability. For this purpose, we examined the effects of P and Zn fertilization individually and in combination on growth, yield and grain protein content in maize grown in pots filled with three different Mediterranean soils (LCV, FER and INM). Phosphorus and Zn translocation to grain was impaired, and aboveground dry matter and yield at harvest reduced by 8-85% (LCV and FER), in plants treated with Zn or P alone relative to unfertilized (control) plants. In contrast, joint fertilization with P and Zn enhanced translocation of these nutrients to grain and significantly increased aboveground dry matter (30% in LCV, 50% in FER and 250% in INM) and grain Zn availability in comparison with control plants. Also, joint application of both nutrients significantly increased grain P (LCV) and Zn (LCV and FER) use efficiency relative P and Zn, respectively, alone. Yield was increased between 31% in LCV and 121% in FER relative to control plants, albeit not significantly. Fertilization with P or Zn significantly influenced the abundance of specific proteins affecting grain quality (viz., storage, lys-rich and cell wall proteins), which were more abundant in mature grains from plants fertilized with Zn alone and, to a lesser extent, P + Zn. Sustainable strategies in agriculture should consider P-Zn interactions in maize grown on soils with a limited availability of Zn, where Zn fertilization is crucial to ensure grain quality.

Optimum Olsen Phosphorus/ZincDTPA ratio for the initial growth of maize in agricultural soils of the Mediterranean region.

BACKGROUND: Zinc (Zn) deficiency in crops is commonly aggravated by high levels of phosphorus (P) in soil. In this work, the initial performance of pot-growing maize in response to the available P and Zn in soils with low available Zn and to the application of P and Zn fertilizers was investigated. RESULTS: The soils (six non-calcareous and 14 calcareous) ranged widely in available P (Olsen P: 5.5-37.9 mg kg-1 ), were poor in available Zn [diethylenetriaminepentaacetic acid-extractable Zn (ZnDTPA ): 0.20-0.84 mg kg-1 ] and had an Olsen P/ZnDTPA ratio of 13 to 111 mg mg-1 . Soil P application generally increased aerial dry matter (ADM) yield; Zn increased ADM yield mostly when applied in combination with P; and the sole application of Zn increased yield only in a soil with a high (28 mg kg-1 ) Olsen P and a low (0.36 mg kg-1 ) ZnDTPA . The increase in ADM yield resulting from optimal application of P and/or Zn to the soil was modest in soils where the Olsen P/ZnDTPA ratio was 30-60 and Olsen P was >14 mg kg-1 . Zinc uptake by the control plants was correlated with the ZnDTPA of the soil. For a certain ZnDTPA value, the level of plant available Zn was higher in non-calcareous than in calcareous soils. CONCLUSION: Soil application of fertilizer P and Zn, in soils with low levels of available Zn, should not only aim at increasing the available P and Zn levels but also balancing them at the appropriate Olsen P/ZnDTPA ratio, which was found to lie in the 30-60 range in the present study. © 2020 Society of Chemical Industry.

Phosphorus reduces the zinc concentration in cereals pot-grown on calcareous Vertisols from southern Spain.

BACKGROUND: Zinc deficiency, a major problem in crops grown on soils low in available Zn, is even more important in phosphorus-rich soils. This work aimed to elucidate the effects of soil P and Zn levels, and of fertilizer application, on yield and Zn concentration in cereal grains. RESULTS: Wheat and barley were successively pot-grown on 20 calcareous Vertisols low in available Zn and ranging widely in available P. Grain yield in the plants grown on the native soils was positively correlated with Olsen P but not with diethylenetriaminepentaacetic acid (DTPA)-extractable Zn except for wheat on P-rich soils. Grain Zn concentration was negatively correlated with Olsen P. Grain Zn uptake differed little among soils. Application of P to the soils increased grain yield insignificantly and P concentration significantly; however, it reduced grain Zn concentration (particularly at low Olsen P values). Applying Zn alone only increased grain Zn concentration, whereas applying P and Zn in combination increased yield and grain Zn concentration at low and high Olsen P values, respectively. CONCLUSION: Applying P alone to plants grown on calcareous Vertisols low in available P and Zn may in practice reduce grain Zn concentrations while not increasing grain yield significantly. © 2016 Society of Chemical Industry.

The severity of iron chlorosis in sensitive plants is related to soil phosphorus levels.

BACKGROUND: Iron (Fe) deficiency chlorosis, a major nutritional problem in plants growing on calcareous soils, is related to the content and reactivity of soil iron oxides and carbonates. The effects of other soil components, however, need elucidation. In this paper we tested the hypothesis that application of high doses of phosphorus (P) to the soil can aggravate Fe chlorosis. RESULTS: Lupin and sorghum were grown on 24 calcareous soils. Leaf chlorophyll concentration (LCC) in lupin decreased with increasing available P/available Fe ratio in the native soil but LCC in sorghum was unaffected by that ratio. Application of P to the soil resulted in significant reduction of LCC and dry weight in lupin. In sorghum, LCC and dry weight were positively affected by P fertilisation for soils poor in available P whereas the opposite effect was generally observed for the P-rich soils. In another experiment where olive plants were pot-grown on two soils during the 2009­2011 period, P fertilisation affected LCC negatively only in 2009 and 2011 and in the soil that was poorer in iron oxides. CONCLUSION: Application of fertiliser P to Fe chlorosis-inducing soils is likely to aggravate this deficiency. However, this effect depends on the plant and the Fe and P statuses of the soil.