نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشجوی دکتری علوم خاک دانشگاه تهران
2 دانشیار گروه مهندسی علوم خاک دانشگاه تهران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Regarding to phosphorus as a low mobility element in soil, identification and application of traits of cultivars that are recognized as phosphorus efficient, will be very important for crop improvement and optimum usage of soil. Maximizing the phosphorus use efficiency of crops in the system is one of the most important approaches considered in phosphorus management. The first step in improving effectiveness of nutrient management practices is having information about how plant root systems interact with the soil. Because of limited researches on function of roots at the uptake of low mobile elements, this investigation was conducted to study some root morphological properties of several phosphorus efficient and phosphorus inefficient cultivars of wheat and their relations with phosphorus efficiency indexes.
Materials and methods: In this study, some root morphological properties of several phosphorus-efficient and phosphorus-inefficient cultivars of wheat (Triticum aestivum L.) were compared and their correlations with efficiency indexes were studied. Furthermore, the rhizosphere effect of each cultivar on soil pH and soil phosphorus fractions was investigated. A greenhouse experiment on wheat cultivars as a factorial in completely randomized design was conducted with 8 treatments and 3 replications for six weeks. Experimental factors were different cultivars (2 phosphorus efficient i.e. Azadi and Yavarus and 2 phosphorus inefficient i.e. Karaj 1 and Marvdasht) and soil P levels (natural level of soil P and 20 mg P kg-1 soil). To understand root properties effecting phosphorus efficiency related to cultivar, some root morphological properties (root wet weight, root dry weight and root volume) were measured and then total root length and root surface area were calculated. Shoot wet and dry weight and shoot to root ratio in different cultivars was measured and calculated, too. Finally, total phosphorus uptake, phosphorus acquisition efficiency, phosphorus utilization efficiency and phosphorus efficiency were calculated and correlation between root morphological properties and efficiency indexes was investigated.
Results: There was a significant (p<0.05) difference of root morphological properties between phosphorus efficient and phosphorus inefficient cultivars and with higher efficient cultivars produced stronger and more extensive root system. Azadi and Marvdasht cultivars had the highest and lowest root quantitative properties (wet weight (2.27 and 1.28 g), dry weight (0.31 and 0.20 g), total root length (278.4 and 179.04 Cm), root surface area (90.2 and 56.06 Cm2/pot) and root volume (2.3 and 1.4 mL/pot), respectively. Also, different cultivars showed significant differences (p<0.05) in the dry weight of shoots, shoot to root ratio, shoot P concentration and shoot total uptake as well as phosphorus acquisition efficiency and phosphorus utilization efficiency. Dry matter was significantly (p<0.05) increased for all cultivars with phosphorus fertilization. There was a positive and significant correlation between root parameters of studied cultivars with different efficiency indexes such as shoot phosphorus concentration and shoot total phosphorus absorption but there was a negative correlation between mentioned parameters with phosphorus utilization efficiency index. Soil pH values in the rhizosphere of all four wheat cultivars were significantly (p<0.05) lower than those in the corresponding non-rhizosphere soil. pH decreased between 0.12-0.38 in the rhizosphere of studied cultivars. Azadi and Marvdasht cultivars showed the most and the least amount of pH decreases, respectively. All wheat cultivars decreased phosphorus forms (DCP-P, OCP-P, Al-P and Apatite-P) significantly (p<0.05). This difference was not equal for all cultivars and all fractions.
Conclusion: The differences are attributed to genetic differences among cultivars, root size, root morphology and changes in the rhizosphere. Identification of plants strategies for adoption to low nutrient condition and the right selection of the cultivars can improve the uptake of P in P-deficient soils and crop production.
کلیدواژهها [English]
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