India is one of the richest countries for plant diversity with approximately 16,000 vascular plants, 5000 endemic species and 140 endemic genera. However, an estimated 3000-4000 plant species are being threatened to be on the verge of extinction, fixing India, one of the highest priorities for plant biodiversity conservation. In recent decades, India has increasingly recognized the importance of plant diversity in efforts to conserve and sustainably use its plant diversity. Conservation requires a sound scientific and technical basis and there are two methods viz., ex situ and in situ conservation which are equally important and should be regarded as complementary. In the process of ex situ conservation, the National Bureau of Plant Genetic Resources (NBPGR) possess 3,85,645 germplasm accessions of various agri- horticultural crops. Realising the need of ago biodiversity conservation, TNAU has created a gene bank facility named after the legendary rice breeder Dr. K. Ramiah, with the capacity to conserve more than 1,00,000 germplasm accession under medium term storage (MTS) and long term storage (LTS) conditions. Presently a total of 13,567 accessions of more than 21 species are deposited in the gene bank. These provide an important reserve of plant resources for sustainable economic and social development. Thus, TNAU's strategic and vision for conservation of plant diversity and sustainable use of plant resources in the 21 st century is of far-reaching significance for sustainable development of our economy and society.

A field experiment was conducted at Aliyarnagar involving groundnut-sorghum crop rotation to study the effect of nutrients applied to groundnut on the succeeding sorghum crop. The results revealed that application of 45 kg/ha phosphorus along with the recommended doses of other nutrients to groundnut, minimised the fertiliser requirement of sorghum to the tune of 1/3rd of the recommended dose

ALR 3a disease resistant groundnut variety was release for cultivation in Tamil Nadu. This is a double cross derivative of R33-1 x ICG (FDRS) 68 x Nc Ac 17090 x ALR 1. This new variety is resistant to rust, leaf hopper, thrips and moderately resistant to late leaf spot disease, maturing in 110 to 115 days and has recorded 52 per cent increased yield over the check ALR 2.

Among the five species of Stylosanthes, viz.. S. scabra. Shamata, S. humulis, S.quianensis and S. viscosa tested for yield potential at the Department of Forage Crops, Tamil Nadu Agricultural University, Coimbatore. S.scabra was found superior. This species recorded 26.57 tons of green fodder 8.79 tons of dry matter, and 1.48 tons of crude protein per ha per year. It also had maximum dry matter content, plant height, branches and leaves per plant. Based on the desirable traits and high green fodder yield potential, Stylosanthes scabra was released under the local name Muyal masal by the Tamil Nadu Agricultural University, Coimbatore in January, 1991.

The tenai culture TNAU 196 is a derivative of the cross involving CO 5 x ISE 248 and was developed in the Department of Millets, Tamil Nadu Agricultural University, Coimbatore. It is a high tillering variety maturing in 85-90 days. The crop can be grown under rainfed conditions during kharif and rabi seasons and also suitable for summer season under irrigated condition wherever such condition exists. The panicle is long measuring 29 cm with densely packed grains. The grain is bold with attractive yellow colour. Extensive trials conducted from 2000 to 2004 in the Millet Breeding Station, other research stations of TNAU and farmers' holdings revealed its high yield potential and wide adaptability. It is capable of giving a mean grain yield of 1855 kg/ha while the National check SIA 326 has recorded 1477 kg/ha. In these trials, the local check CO 6 recorded 1554 kg/ha of grain yield. As compared to checks, TNAU 196 has registered an increase of 25.6 per cent over SIA 326 and 19.37 per cent over CO 6 in respect of grain yield. It is suitable for rainfed condition. In addition to higher yield potential, this culture also shows good grain quality with higher protein content of 13.62 per cent and calcium content of 0.35 per cent than the variety CO 6 in which protein and calcium contents were 11.62 per cent and 0.33 per cent respectively. In view of the high grain yield, grain quality and resistance to rust the culture TNAU 196 was released as new variety CO 7 for Tamil Nadu state during 2005.