Showing 2 results for R. Hajiboland
R. Hajiboland, M. K. Khosrowpanah,
Volume 9, Issue 4 (winter 2006)
Abstract
Manganese toxicity occurs in many agricultural and natural ecosystems under the various soil conditions such as the nature of substrate, acidity, flooding or vicinity to the mining areas. The objective of this work was to study the effects of excess Mn in the growth medium on three important crop species, namely rice (Oryza sativa L. cv. T. Hashemi), maize (Zea mays L. cv. SC.704) and sunflower (Helianthus annuus L. Mehr). Plants were cultured in the hydroponic medium under controlled environmental conditions and treated with 0 (control), 25 50, 75 and 100 µM Mn for 12 days. Dry mass production, the effect of supplemental Mg and Ca on the toxicity expression, root respiration and K+ leakage from shoot and root tissues were studied under the Mn treatments. In order to study the effect of light intensity on the expression of toxicity symptoms, plants were cultured under the different light conditions, thereafter their growth and metal uptake and transport were studied. Sunflower plants treated with the 50 µM Mn and higher, showed dark-brown spots associated with the trichomes on the leaves and petioles. Maize plants developed interveinal chlorosis and any visual leaf symptoms was observed in rice. In all of the studied species, a great portion of the absorbed Mn was translocated into shoot, the highest transport was observed in sunflower and the lowest in maize. No significant correlation was observed between the expression of Mn toxicity and the accumulation rate of Mn. Growing under the low light intensity, in addition to the lowering biomass production, increased or decreased the toxicity effect depending on species. Mn-toxicity-induced root respiration was not associated with the differential response of species to Mn toxicity. In contrast the change of K+ leakage from shoot and root tissues was well correlated with the toxicity response of tested plants.
R. Hajiboland, S.y. Salehi, T. Aghajan-Zadeh, M. Abhari, E. Nazifi,
Volume 11, Issue 1 (spring 2007)
Abstract
Zn deficiency is one of the most important nutritional disorders after macro-nutrients in rice. There are considerable genotypic differences among rice genotypes in response to Zn deficiency. Determination of such differences and introduction of efficient genotypes could lead to significant reduction of fertilizer use for rice production. In this research, some of the most frequently cultivated rice genotypes in Northern Iran, were compared for their tolerance to Zn deficiency in a field (11 cultivars) and hydroponic (16 cultivars) experiment. Four levels of Zn fertilizer were used in field experiment including 0 (control), 25, 50 and 100 kg ha-1 and three different activity of Zn in chelator-buffer experiment including 130 (control), 23 and 5 pM. Experiments were conducted using complete randomized block design and data was analyzed using two factorial analysis of variance including Zn level and genotypes. In addition to yield components in the field study and dry matter production in the hydroponic culture medium, concentration of Zn was also determined in shoot, root and seed. The comparison of all yield components showed that the cultivar Onda was the most Zn-inefficient (susceptible to Zn deficiency) and Khazar was the most Zn-efficient (tolerant to Zn deficiency) genotypes under field conditions. In hydroponic experiment, cultivars Fajr, Tarom Hashemi and Onda were determined as the most Zn-inefficient and Shafagh, Amol and Mianeh were recognized as the most Zn-efficient genotypes. The most significant response to Zn fertilizer, in terms of Zn accumulation in seeds, was observed in Nemat and Tarom Deilamani. In contrast, Cadoos accumulated Zn mostly in straw. Results of our experiments introduced not only the genotypes with the highest yield on soils low in available Zn, but also genotypes with the highest Zn accumulation in seeds in response to Zn fertilizers which are important for human nutrition.
