Thumbnail Image

Assam Agricultural University, Jorhat

Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level. Genesis of AAU - The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati. Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.

Browse

20191
Reset filters
Subject: Plant Pathology × Author: Baruah, Borsha Rani × End date: 2019 × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Evaluation of protective strains for cross-protection against Citrus tristeza virus disease
    (2019-07) Baruah, Borsha Rani; Nath, P. D.
    For Citrus tristeza virus strains differentiation and identification, leaf samples were collected from Khasi Mandarin (Citrus reticulata) plants expressing differential symptoms from three different locations viz., Tinsukia, Golaghat and Mariani of Upper Brahmaputra Valley Zone of Assam. These were then grouped into three categories, viz. low range, medium range and high range based on ELISA OD405 values. Biological indexing with CTV positive samples from these three serological categories on Mexican lime or Kaghzi lime (Citrus aurantifolia) seedlings resulted in symptom expression within three months post grafting. Visible symptoms of CTV infection were observed in some of the graft successful indicator plants whereas, in some plants, no visible symptom development took place within this period. Based on the results, the plants were grouped into two groups- mild and severe, and were confirmed through Bi-directional PCR with mild and severe strain specific primers. PCR products for both mild and severe isolates were sequenced. Consensus sequences showed a single nucleotide difference at position 371 for mild and severe isolates, thereby confirming the identity. Two mild isolates and two severe isolates were selected for the cross protection experiment on Khasi mandarin seedlings. Cross protection experiment was carried out in seven treatments with five replications. Real time-PCR analysis of the grafted plants was carried out six months post grafting to determine the virus titre values through absolute quantification by developing an external standard curve with the equation ‗y = -3.0543x + 37.018‘ (R2 = 0.9981), using 6 serial dilutions of eluted DNA (10-1 to 10-6). The average estimated gRNA copies were 1.02 x 105 + 8.33 x 103 mol/ng and 9.55 x 104 + 5.89 x 103 mol/ng of total RNA in mild inoculated plants, 3.80 x 105 + 3.05 x 104 mol/ng and 3.94 x 105 + 3.53 x 104 mol/ng in severe inoculated plants and, 2.20 x 104 + 2.14 x 103 mol/ng and 3.44 x 104 + 3.20 x 103 mol/ng in mild inoculated plants, later challenged by severe, with no observed amplification in the un-inoculated control. It was observed that the mild inoculated plants, challenged by severe i.e. cross protected plants exhibited the lowest virus copy numbers. Melting curve analysis revealed that the Tm of the mild CTV isolates (80.37–80.820C) was lower than that of the severe isolates (81.57–81.970C). In the cross protected plants, Tm in the range of 80.73-80.880C was recorded, indicating the presence of mild isolates.