Abstract:The present investigation was carried out to screen genotypes for resistance to Early blight disease of tomato (Solanum lycopersicum L.) of North Eastern region of India. Field trial was conducted in the Experimental Farm, Department of Horticulture, Assam Agricultural University, Jorhat during the years 2012-13 and 2013-14 consecutively. The disease severity of tomato genotypes was assessed by 0-5 points scale, percent Disease Incidence (PDI). Of the total materials screened, Sel-35 (TLBRH-6 X Konbilahi) and Sel-19 (TLBRH-6 X Konbilahi) were highly resistant, 7 were resistant, 14 were moderately resistant, 16 were susceptible and 6 were highly susceptible under field condition after inoculation during both years. The genotype having high yield and resistant to early blight was 10/TOLCVRES-3. The genotypes resistant to early blight but having low yield and Sel-16) may be utilized in future breeding programme for improving yield through selection for higher fruit weight and fruit diameter. Alternatively, they may be used as parents in hybridization or backcrossing programme in order to transfer the gene for resistance to early blight to already adapted high yield varieties.

Capsicum chinense Jacq. is well known for its pungency factor, "capsaicin". An attempt has been made to maintain the desired pungency of Capsicum chinense Jacq. cv. Lota Bhot through in vitro propagation via callusogenesis from leaf explants under the influence of different plant growth hormones and an additional component, Silver nitrate (AgNO3). The combination of Kinetin (45µML -1 ) along with 2,4-Dichlorophenoxy Acetic Acid (2,4-D) and AgNO3 at 3.5µML -1 and 35µML -1 respectively was found optimum for callus induction as well as multiple shoot induction whereas maximum shoot length was recorded at Kin (40µML -1 ), 2,4-D (3.0 µML -1 ) and AgNO3 (30µML -1 ). In vitro flower induction and fruit development was most observed under the influence of Gibberellic Acid (GA3) at 30µML -1 . Murashige and Skoog (MS) medium fortified with Benzyl Amino Purine (BAP) 1 and 2,4-D at 4.0µML -1 and 5.5 µML -1 correspondingly was standardized for maximum induction of roots in vitro. Healthy in vitro regenerated plantlets were acclimatized in the potting substrate containing half strength MS medium enriched with soil, sand, vermicompost and vermiculite in all equal proportion and 78.56% of total acclimatized plants were successfully transferred to the main field.

Naga chilli or Bhut jolokia is extensively cultivated all over northeast India including Assam. This chilli is of high commercially value due to its pungent trait called capsaicin. The chilli is well known to have extreme potential for numerous pharmaceutical applications apart from being used for culinary purposes. Despite being such an important spice crop, demand of Naga chilli is deteriorating owing to natural cross pollination and mutation which in turn reduce its capsaicin content. Therefore, an attempt was made to conserve the germplasm through standardization of an efficient micropropagation protocol using different plant hormones, silver nitrate (AgNO 3 ) and tryptophan as the key components. In vitro propagation was carried out with leaf explants. MS medium was supplemented with different combinations of BAP, 2,4-D, GA 3 , NAA and IBA alongside AgNO 3 and tryptophan. Maximum callus induction took place in the presence of 2,4-D (3.5mg/L), AgNO 3 (3mg/L) and trptophan (3mg/L). Addition of AgNO 3 to the culture medium greatly enhanced shoot proliferation in the selected in vitro plantlets. In vitro flower induction and fruit formation were successfully carried out in the presence of GA 3 (3.5mg/L) and AgNO 3 (3.5mg/L). Maximum root initiation was observed in the MS medium supplemented with IBA (3mg/L), GA 3 (2.5mg/L) and AgNO 3 (3mg/L). Hardening of in vitro raised plantlets was successful in sterile soil enriched with vermicompost and vermiculite. Percentage of plant survival was 84.75%. Addition of biofertilizers greatly improved the chances of acclimatization of in vitro raised healthy plantlets. K e y w o r d sNaga chilli, In vitro propagation, Silver nitrate, tryptophan

A hybrid development programme on okra (Abelmoschus esculentus) was undertaken at the Assam Agricultural University (AAU), Jorhat. The work included collection and evaluation of okra germplasm, identification of parents for hybridization, selfing of identified parental lines, making crosses and production of hybrid seeds, testing of hybrids for yield and resistance to Yellow Vein Mosaic Virus (YVMV) disease, adaptability under diverse agro-climatic condition and testing in all India trials. The programme resulted in development and identification of excellent Okra hybrid AAUOKHYB-1 in 2017.  The performance of the hybrid was very good under diverse agro-climatic conditions yielding about 162.0 q/ha fruit yield which is 32.5% higher than the best commercial check Arka Anamika. The hybrid showed resistant (R) reaction to YVMV disease. A wide range of heterosis upto 43% was exhibited by the hybrid in different vegetable research centers of the country as compared to the best check variety.