Ali Monsefi
Abstract
Introduction Herbicides are chemicals that are used to inhibit the growth or to eliminate weeds in agricultural fields to increase the yield of crops in crop production. By the end of the 19th century, with the increasing labor supply problems, the need for chemical methods to control weeds became apparent. ...
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Introduction Herbicides are chemicals that are used to inhibit the growth or to eliminate weeds in agricultural fields to increase the yield of crops in crop production. By the end of the 19th century, with the increasing labor supply problems, the need for chemical methods to control weeds became apparent. It was first reported in France in the 1980s, that sulfuric acid was used in the fight against weeds in sugar beet fields. Nowadays, most of the herbicides used are organic herbicides, which share organic carbon in their chemical structure. The use of herbicides since about a century ago has been suggested as an effective way of eliminating crop competitors, though herbicides that remain in the soil for longer periods of time prolong weed control and thus increase weed management efficiency. On the other hand, their increased stability in soil may be of a magnitude that can damage crops in the following crop rotations. Soil properties can have a significant impact on the stability of herbicides in soil. Materials and Methods For this purpose, soil samples were taken from 0-30 cm depth from field of experiment No. 2 in College of Agriculture Shahid Chamran University of Ahvaz. After sampling and passing through 2 mm sieve, the physical and chemical properties were measured using standard methods. The pot experiment was conducted in a factorial completely randomized design with 32 treatments including soil salinity (at 2.5 and 6 dS / m), Ultimo herbicide rate (at 4 concentration levels of 0, 25, 50 and 100% Recommended dose) and planting time (60 and 120 days after herbicide application) with 3 replication. Wheat was selected as the experimental crop and variety was "Mehregan" which has been cultivated in most of Khozestan province. Herbicide was applied and soil was rested for 60 and 120 days then wheat was sown. For germination percentage, wheat seeds were sown directly in soil after germination test. After germination the percentages were recorded and kept in an equal number of plants in the pot. It should be noted that in order to eliminate the effect of nutrient deficiency on plant growth at appropriate intervals, nutrient solution was applied and irrigated according to the need of the plant.After 9 weeks (before flowering stage) the plant was harvested and the growth components including root length, root dry weight, shoot length, shoot weight and nutrient concentration including nitrogen (in plant dry matter), phosphorus, potassium, calcium, magnesium, iron, zinc, copper and manganese were measured in the extract obtained from dry digestion of plant tissue (aerial parts of plant). Statistical analysis was performed using SAS software and mean comparisons were performed by Duncan's multiple range test. Charts were drawn using Excel software. Results and Discussion According to the results, increasing the level of herbicide decreased the growth parameters of the plant, which is intensive under salinity stress. The results showed that considering 60 days sowing after herbicide application, shoot dry weight in 100% RD herbicide application in salinity of 2.5 dS/m was 1.6 g which was not showed significant difference with 50% herbicide application under salinity of 6 dS/m. Therefore, in higher salinity levels lower herbicide dose can damage the plant as much as higher levels of herbicides in lower salinity, and lower levels of herbicides in more soil salinity produce more negative effects. By increasing planting time from 60 to 120 days the residual effects of herbicides on soil decreased and plant showed better yield. By increasing salinity level from 2.5 to 6 dS / m, all growth components of wheat decreased, except for shoot length and shoot dry weight, this significant decrease was not reported for other components. Conclusion Therefore, it can be concluded that selection of sowing time after herbicide application in crop rotations is very important and by selecting the correct time can greatly reduce the deleterious effects of consuming more herbicides.Planting wheat at 60 days after application of herbicide compared to 120 days after application of herbicide, decreased the growth components of the plant. Therefore, selection of wheat sowing time in crop rotation 60 days after application of herbicide (especially at 100% recommended dose) is not recommended in maize – wheat cropping system. Also considering soil chemical properties such as salinity as an influencing factor on herbicide behavior in soil can be effective in controlling residual effects of herbicides in soil and plant.
Plant Nutrition, Soil Fertility and Fertilizers
Hananeh Bahmaniyan; Habibollah Nadian Ghomsheh; Nafiseh Rang Zan
Abstract
Introduction With limited arable land available around the word, some ways can be used to increase the production per unit area to meet the increasing human need for food. In addition to quantity, consideration of quality of products can lead to improve communities’ health. So, in the last few ...
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Introduction With limited arable land available around the word, some ways can be used to increase the production per unit area to meet the increasing human need for food. In addition to quantity, consideration of quality of products can lead to improve communities’ health. So, in the last few decades, application of organic and bio fertilizers has been taken into account in order to increase quantity of products as well as their quality. Mycorrhiza fungi are the most abundant microorganisms in the soil and are considered as essential factor in sustainable soil-plant system. The use of existing organic and inorganic fertilizers may stimulate the Mycorrhiza-plant root symbiosis and ensure the supply of nutrients to the plant for sustainable production. Filtercake is a main byproduct of sugarcane industry which is obtain during the processing of sugarcane syrup. Filtercake can be transformed into the valuable source of nutrients by biodegradation processes. Many studies have suggested that the use of fertilizers along with Mycorrhiza, especially phosphorous fertilizers, has negative effects on fungi symbiosis with plant root. Regarding this issue, the question arises that due to richness of Filtercake of organic matter, nutrients and microorganisms, is the Mycorrhiza interdependency affected by the addition of this organic manure to the soil? In order to answer this question, the present study was conducted to investigatethe interaction effect of Mycorrhiza(Glomus Intraradices)andFiltercake on coriander (Coriandrum Sativum L.) production. Materials and Methods In order to study the interaction effect of Filtercake and Mycorrhiza on the coriander production, a pot experiment was conducted in factorial completely randomized design with consideration of Mycorrhiza fungi (Glomus Intraradices) treatments at two levels of non-inoculation (m1) and inoculation with Mycorrhiza (m2), Filtercake in three levels of zero (f1), 1.5 (f2) and 3 wt.% (f3) with coriander (Coriandrum sativum L.) as experimental plant in 4 replicates in the greenhouse of Agricultural Sciences and Natural Resources University of Khuzestan during 2017-2018. Twelve weeks after sowing plants were harvested and considered parameters were measured. Data analysis was performed using SAS. Comparison of the meanings was performed using Duncan's test at 5% level. Excel were used to draw charts and graphs. Results and Discussion The highest plant height and root length were observed in treatment consist of Mycorrhiza and 3% Filtercake. Same trend was observed in case of aboveground (cilantro) and root dry weight. The presence of organic matter, increasing of quasi-hormonal activity and improvement of physical, chemical and biological properties of soil are among the factors that provide favorable conditions for vegetative growth and, as a result, increase plant yield. The application of Mycorrhiza increases concentrations of phosphorus, potassium, calcium and magnesium in cilantro, at about 103, 40, 16 and 12 percent, respectively, which are about 11, 105 and 31 percent in case of iron, zinc and copper. Mycorrhiza has a positive effect on the nutrients content in plant, which can be attributed to increased absorption through the fungal hyphae and also to the enrichment of the plant's rhizosphere. The concentration of nutrients in cilantro was significantly increased due to increase in Filtercake level. Since most of the nutrients in the soil are immobilized, the addition of Mycorrhiza fungi can help to improve nutrient uptake by increasing the volume of root access and stimulating the mineralization processes. Application of Filtercake along with Mycorrhiza improves the biological status of the fungi. Increasing the level of the Filtercake from 0 to 3 percent increases colonized Root length, Mycorrhiza interdependency and colonization percent by 51, 22 and 28 percent, respectively. According to the results, the use of Filtercake not only does not reduce the Mycorrhiza indices, but also increases them and act as a key factor for encouraging symbiosis of fungi and plant, so contribute to the enhancement of plant growth parameters. Conclusion In most of the studied characteristics, the maximum amount were observed in the treatment containing 3% Filtercake and Mycorrhiza. So, the simultaneous application of Filtercake and Mycorrhiza increased the growth parameters of the coriander. Although both of treatments (Filtercake and Mycorrhiza) have been effective in increasing the concentration of essential elements in aboveground part of plant, the effect of Mycorrhiza on increasing the concentration of phosphorus and zinc is greater than its effect on other elements, which is for iron and copper in case of Filtercake. The use of organic manure, such as Filtercake, even with high nutrient content, cannot affect the Mycorrhiza interdependency and other colonization indices due to the low release rate of these elements into the soil environment. It seems that the combination of Mycorrhiza and Filtercake by increasing the microbial and enzymatic activities in the soil and the separate application of Mycorrhiza and Filtercake by improving the access ability of the nutrients leads to provide better growth of the plant.
