Document Type : Applicable
Authors
1 Ph.D. student in Soil Science, Department of Soil Science Engineering, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
2 Associate Professor, Department of Soil Science Engineering, Faculty of Agriculture, Lorestan University, Khorramabad, Iran
3 Professor, Department of Soil Science Engineering, Faculty of Agriculture, Ferdowsi University, Mashhad, Iran
Abstract
Introduction Today, the use of biochar to reduce the adverse effects of environmental stress such as heavy metal stress and drought stress has increased rapidly. Biochar reduces the adsorption of these metals by plants through the adsorption of soil pollutants on its surface due to the porous system and the presence of important functional groups such as carboxyl, phenolic and hydroxyl. Research has shown that by changing the surface characteristics of biochar, including specific surface area, pore volume and the content of functional groups, especially oxygen-containing groups, it is possible to increase the ability of biochar to adsorb heavy metals. Another important solution that has been started today to improve the quality of soil, agricultural products and remove pollutants is the use of nanotechnology. Today, zinc oxide nanoparticles are used in agriculture and related sectors. Zinc is a mineral element for plant growth and has beneficial and harmful effects on various aspects of plant growth. Forage corn (Zea mays) is one of the most important grains in the world and is very important in providing energy for animals. According to the studies conducted, one of the most important factors that has reduced the yield of forage corn in the world is drought stress, in addition to this, heavy metals may also be involved in this matter, so although there are various solutions to overcome the stress drought and pollution caused by heavy metals in forage corn, however, the effect of biochar enriched with zinc nanoparticles in these conditions has not been well investigated; Therefore, considering the importance of the forage corn in the human and livestock food chain, the main objective of this research is the role of biochar and biochar enriched with zinc nanoparticles in reducing the negative effects of deficit irrigation and arsenic on some morphological and physiological characteristics of forage corn.
Materials and Methods Experimental factors include 5 levels of biochar: control (no use of biochar), 0.5 and 1% by weight of plain biochar, 0.5 and 1% by weight of biochar enriched with zinc nanoparticles and three irrigation levels: control (100), 75 and 55% of Field Capacity (FC)). In this study, green walnut skin was used to prepare biochar. Zinc oxide nanoparticles were used for biochar enrichment. At first, 0.2 % of the weight of biochar was weighed from nanoparticles, and then it was brought to a certain volume with distilled water. The produced suspension was shaken overnight at room temperature. After this step, the sediment produced was washed several times and dried in an oven at 100 degrees for 12 hours. Then it was weighed according to the experimental treatments and mixed separately with the soil of the pot, which was previously contaminated with arsenic from the source of Na2HAsO4.7H2O in the amount of 50 mg/kg of soil. To determine the FC, the weight method was used, and based on the soil moisture level, the levels of 75 and 55% of the FC were calculated, and the test plants were irrigated by the weight method of the pots every other day. After the completion of the vegetative growth and before entering the reproductive growth, the samples were taken. Then some morphological and physiological traits of the plant were measured.
Results and Discussion The results showed that the application of biochar (unenriched) and enriched biochar reduced the negative effect of arsenic and deficit irrigation. So that the highest fresh weight (43.95 gr per pot) and dry weight (5.36 gr per pot) of leaves in the treatment of 0.5% weight enriched biochar, the highest, height (87.86 cm), chlorophyll a (17.52 mg/g leaf weight) and total chlorophyll (26 mg/g leaf weight) in the treatment of 1% enriched biochar and the most chlorophyll b (8.73 mg/g leaf weight), cartenoid (5.65 mg/g leaf weight), RWC (79.19%) was observed in the treatment of 1% biochar (unenriched) and control treatment (100% FC). The results also showed that the highest (17.21 mg/kg) and the lowest (11.74 mg/kg) available arsenic were in the 0.5% enriched biochar treatment and the control treatment (no use of biochar) respectively, highest zinc uptake in leaf (393.04 µ/ pot) in the treatment of 1% enriched biochar and full irrigation (100% FC) and the lowest amount (105.55 04 µ/pot) in the control treatment (no use of biochar) and severe irrigation deficiency (55% FC) was observed; While highest arsenic uptake in leaf (18.58 µ/pot) in the control treatment (no use of biochar) and severe deficit irrigation (55% FC) and the lowest amount (2.34 µ/pot) in The treatment of 1% enriched biochar and complete irrigation was observed; which can be related to the effective role of enriched biochar in reducing arsenic absorption in severe irrigation conditions. Finally, considering the favorable effect of biochar in improving the growth and physiological characteristics of forage corn and reducing the absorption of arsenic at different levels of irrigation, it can be said that in soils contaminated with arsenic, the addition of biochar plays an effective role in improving plant growth in deficit irrigation.
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