1. At 80% variability (Fig.1.) the accessions were grouped into three clusters and two independent accessions, numbered 23 and 55. Accession no. 55 (O. nivara) had highest mean values for leaf conductance transpiration rate, photosynthetic rate and plant height Accession number 23 is a weedy rice collected from the DWSR Farm in Jabalpur Cluster1 includes four weedy rice accessions only. Cluster 2 includes the largely cultivated rice varieties of Madhya Pradesh Mahamaya, Kranti and JR 201 along with 20 weedy rice accessions. Cluster 3 has the cultivated varieties Pusa Basmati and IR 64 and wild O. rufipogon along with 24 weedy rice accessions. MORPHO-PHYSIOLOGICAL DIVERSITY IN WEEDY RICE (O. sativa f. spontanea) ACCESSIONS COLLECTED FROM CENTRAL INDIA Meenal Rathore, Raghwendra Singh, Yogita Gharde and Bhumesh Kumar Directorate of Weed Science Research, Maharajpur, Adhartal, Jabalpur, Madhya Pradesh-482 004, India Weedy rice, a conspecific weed of rice has already spread across the globe infesting fields of rice and affecting the produce. With an increase in labor costs and water scarcity in many Asian countries, transplantation of rice is being replaced with direct seeding. This weedy rice, which otherwise is suppressed under water logged conditions now emerges with the crop and competes for space, air and nutrition. And as no selective herbicide is available to control weedy rice, and no single method is efficient enough to do the same; the problem is aggravating. It is hypothesized that weedy rice have largely emerged as a result of natural hybridization between wild rice and cultivated rice ( Jiang et al,2012). Being a biosimilar of the AA complex of rice, it shares traits of both cultivated and wild rice and cannot be differentiated at tillering stage. Weedy rice infestations in the range of 5-60% across different states were first reported in India in 2008. Himachal Pradesh had the highest infestation (50-60%) followed by Madhya Pradesh (11-44 %) in farmers fields. Inspite of the increasing infestation across the Nation, limited information is available on morphological diversity among different populations while no information is available on the physiological aspects of weedy rice. Introduction There is high variability amongst the weedy rice accessions as evident from clustering pattern. Weedy rice accessions of cluster 2 are more close to cultivated rice and those in cluster 3 are more close to the wild O. rufipogon. Accession number 23, a weedy rice, is very divergent from others. Oryza nivara remains distant from cultivated and weedy rice from Madhya Pradesh. Accession No 55 Accession No 23 Cluster 1 Cluster 2 Cluster 3 Leaf Temperature ( 0 C)33.6533.3332.8134.3333.86 Leaf Conductance0.070.06 0.050.07 Transpiration rate ( mMol H 2 O m -2 s -1) 3.672.962.942.493.57 Photosynthetic rate ( mMol Co 2 m -2 s -1 ) 17.512.213.09.117.3 Plant height (cm)115.992.889.059.998.3 SPAD38.338.840.738.440.7 No of tillers (no.)39.549.633.255.276.4 Table 1: Cluster mean value for different characters 1.Jiang, Z., Xia, H., Basso, B., and Lu, B.R., Introgression from cultivated rice influences genetic differentiation of weedy rice populations at a local spatial scale. Theor. Appl. Genet., 2012, 124: 309-322. 2.Varshney, J.G. and Tiwari, J.P., Studies on weedy rice infestation and assessment of its impact on rice production. Indian J Weed Sci., 2008, 40(3&4): 115-123 1.Assessment of genetic variability amongst weedy, wild and cultivated rice using molecular tools. 2. Expanding the study to weedy rice accessions collected from different states of India. The authors are thankful to Directorate of Weed Science Research, Jabalpur for financial support and Director, CRRI, Cuttack for providing germplasm of wild rice used in the study. Sample collection from Central India Sh. Lekh Ram Yadav Sh. Sunil Thakur Kranti Sunder Lat. 23.16.28.8 Long. 79.59.52.0Lat. 23.16.04.4 Long. 79.59.53.6Experimental Field ( 45-60 DAS) ~ 5.5.ft., ~ 50 no. ~2.5.ft ~ 1.5.ft ~ 50 no. Variations in grain morphology) Awnless. Straw hull Awned. Brown hull Awned Dark brown hull Know your weed to manage it better Genetic variations are visible in phenotype that can be measured in morphological and physiological parameters. And hence assessment of i)morpho-physological variability of weedy rice accessions collected from Madhya Pradesh amongst themselves and ii)variability with the rice progenitor-wild rice (Oryza rufipogon and O. nivara) and popular rice cultivars of the state was done to get an insight into available diversity in the germplasm collected. This is the first diversity assessment of weedy rice based on morpho-physiological parameters in Indian subcontinent  Forty nine accessions of weedy rice biosimilars collected from Madhya Pradesh in Kharif 2011 were grown in 2012 in the Experimental field by direct seeding (DSR) in augmented block design having five cultivated rice and two wild rice species.  All the entries were evaluated for plant height, tiller number, SPAD and IRGA parameters (photosynthetic rate, transpiration rate, leaf temperature and conductance) at 60 days after sowing.  The continuous data was analyzed using Cluster Analysis procedure of statistical package SAS 9.3 (SAS Institute Inc.). Dissimilarity coefficients were calculated using average linkage method of Cluster Analysis procedure. Objectives : Material and Methods Results: Conclusion: Future Prospects: Acknowledgements: References: Contact: Meenal Rathore, Senior Scientist, Plant Biotechnology Indian Council of Agricultural Research, Directorate of Weed Science Research, Maharajpur, Adhartal, Jabalpur Pin: 482004, Madhya Pradesh, India Phone: +91-8989755865 Email: mnl.rthr@gmail.com