World Journal of Agricultural Sciences 1 (1): 98-100, 2005 ISSN 1817-3047 © IDOSI Publications, 2005 Corresponding Author: Dr. U. Surendran, Department of Soil Science and Agricultural Chemistry, Center for Soil and Crop Management Studies (SCMS), Tamil Nadu Agricultural University, Coimbatore-641003, Tamil Nadu, India Tel: + 9443791090 98 Screening of Sorghum (Sorghum bicolor) Genotypes for Their Iron Efficiency R. Krishnasamy, D. Jegadeeswari, U. Surendran and C. Sudhalakshmi Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore - 641 003, Tamil Nadu, India Abstract: The role of plant factors on micronutrient uptake and utilization has been a highly neglected field. The root-soil interface (rhizosphere) plays an important role for iron acquisition. In the present study an attempt was made to screen sorghum genotypes for their tolerance to iron stress. A suitable methodology was developed for the initial screening with modified Hoagland’s solution. Varieties like K 1, K 8, K 10, K 11, Co 26 and CSV 15 exhibited no or less severe symptoms of iron chlorosis and are highly tolerant to iron deficiency hence classified as resistant. Genotypes / cultures like VMS 98001, Co 21, Co 25 and DMS 652 exhibited chlorosis within few days in all the treatments till the end of the study and rated as susceptible. Varieties like APK 1, TNS 340, TNS 587, Co 18 and TNS 334 exhibited chlorosis in control and lower iron levels and they reclaimed green, when Fe was applied and hence they were classified under moderately tolerant group. These Fe resistant genotypes can be grown in Fe deficient soils without incurring any additional cost on Fe containing fertilizers. Key words: Genotypes iron stress resistant susceptible INTRODUCTION values and calcium levels of soils, one has to look into Iron is the fourth abundant element in lithosphere deficiency in plants. and constitutes about 5% of the earth crust. Since iron In order to overcome this discrepancy, higher plants may concentrate or depleted during the soil development have developed different mechanisms to increase the its normal concentration in soil varies widely from 0.7 to solubility of iron in the rhizosphere and the uptake of iron. 55%. Iron is an essential micronutrient for almost all living The role of plant factors on micronutrient uptake and organisms because of tits critical role in processes such utilization has been a highly neglected field. The root-soil as DNA synthesis, respiration and photosynthesis. Many interface (rhizosphere) plays an important role for iron metabolic processes are activated by iron and iron itself acquisition. Plants adapted to iron stress condition have is a prosthetic group constituent of many enzymes. evolved various iron deficiency induced adaptation Discrepancies between the solubility of iron in the mechanisms that are genetically controlled. The inherent soil and the demand for iron by the plant are the primary ability of crop varieties to produce such compounds causes of iron chlorosis. Iron deficiency chlorosis is a differs widely. Some crop varieties respond remarkably to common disorder for plants grown on many soils in iron application while the response is poor in others. India [1, 2]. Although abundant in most well aerated However, there is a paucity of information on the soils, its biological activity is low because it’s primarily response of different varieties to iron application. forms highly insoluble ferric compounds at neutral pH. Therefore, identification of varieties highly susceptible / Investigations conducted by many workers have revealed tolerant to iron deficiency will be of great practical that the problem of iron nutrition is very complex and that significance. The present investigation was framed with no complete cure of iron chlorosis is possible in very the objective of screening sorghum genotypes for their many cases. Also iron fertilization is not helpful as soil tolerance to iron stress. applied iron is fixed in soil due to various chemical reactions. Irrigation water is another contributing factor for carbonates, bicarbonates and sometimes for calcium to the rhizosphere, which immobilize iron in soil. Since it is very difficult to bring about drastic alterations in pH other factors, which can be considered to alleviate iron MATERIALS AND METHODS Plastic trays of 3.5 L capacity were used for conducting hydroponic culture. Plastic plates with