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Morphological and molecular characterization of jackfruit (Artoocarpus heterophyllus Lam) accessions

Thu, 01 Jan 2009 00:00:00 GMT

Title: Morphological and molecular characterization of jackfruit (Artoocarpus heterophyllus Lam) accessions Authors: Anuradha, Sane; G, Kaviya; H, Ravishankar; Prakash, Patil Abstract: DNA profiling and molecular characterization has been increasingly used to validate and establish working germplasm collections and crop improvement programs. Eighteen accessions of jackfruit (Artocarpus heterophyllus Lam) maintained in the field gene bank, IIHR, Hessaraghatta were distinguished at the DNA level by ISSR analysis. Primers that generate accession specific profiles were identified and found useful for generating DNA profiles unique to the jackfruit accessions studied. The cluster diagram depicting genetic relationships between accessions showed that the accessions Gumless, Dorichandra and Tenvarike were the most divergent ones. This study revealed the ability of ISSR markers to detect polymorphism and also to evaluate genetic variability and differentiate accessions of jackfruit. The morphological characterization when collated with DNA profiles of these accessions showed that Tenvarike, which is a divergent accession had desirable fruit characters like low latex exudation and low flake fiber content. Thus molecular marker data together with morphological parameters could be effectively utilized for identifying trait specific germplasm to establish working collections in crop improvement programmes. Further studies are in progress to identify other unique traits viz., earliness, low core thickness, higher number of flakes per fruit, flake thickness, higher total soluble solids etc. integrating molecular analysis with morphological characterization data.

Bird of paradise (Strelitziareginae)- An exotic non traditional cutflower for Southern dry zone of Karnataka.

Thu, 01 Jan 2009 00:00:00 GMT

Title: Bird of paradise (Strelitziareginae)- An exotic non traditional cutflower for Southern dry zone of Karnataka. Authors: Anuradha Sane,; Anil Kumar Nair; M.A. Suryanarayana Abstract: The commercial cultivation of potential exotic flower crop like bird of paradise is gaining importance. It is a less known cut flower with high prospectus but grown on small scale to satisfy special market demands. An experiment was initiated during 2002 at CHES, Hirehalli, Karnataka to study the performance of bird of paradise under southern dry zone of Karnataka. It is an herbaceous evergreen perennial flower crop belonging to Strelitziaceae family. It produces highly attractive orange and blue flowers, which are long lasting and excellent for indoor display. The plants performed well in full sun and survive with very little water once established. The plants flowered within 2 years of planting. Flowering occurred throughout the year with maximum flowering during September -March. The mean values were 128 cm for plant height with 139.22 leaves/pl and 21.52 dichotomous branches/pl. Inflorescence length was 83.09 cm with 4.31 cm stem diameter. No. of florets per inflorescence ranged from 6.2 to 11.8. Growth and yield performance indicated that bird of paradise is a promising crop for southern dry zones of Karnataka.

Diversity and foraging behaviour of pollinator fauna in mango

Fri, 01 Jan 2010 00:00:00 GMT

Title: Diversity and foraging behaviour of pollinator fauna in mango Authors: P, Venkata Rami Reddy; Abraham, Verghese; M R, Dinesh Abstract: Mango (Mangifera indica), the king of fruits, is the pride of Indian fruits There has been a substantial growth in the acreage under mango but the productivity has not increased at the same rate. One of the factors limiting the productivity is the very low percent fruit set (<0.1%) in mango which could be attributed, besides some other factors, to defective or insufficient pollination. Hence pollinators have a significant role to play in enhancing the productivity. A variety of insects visits panicles and potential pollinators can be identified based on species abundance and foraging behaviour. Keeping this in view, studies were conducted at Indian Institute of Horticultural Research, Bangalore during 2009-10 to document the diversity of insect pollinators and assess their role in fruit setting of mango. Insect pollinator fauna was recorded on three popular varieties of mango viz., ‘Alphonso’, ‘Banganapalli’ and ‘Totapuri’. The number of pollinators on 10 panicles in each variety was recorded at 2 hour interval starting from 6 am to 6 pm. Among different species foraging on mango flowers, Apis florea was the dominant one (3.86/panicle/minute) followed by a calliphorid, Chrysomya megacephala (1.62) and a syrphid, Eristalinus arvorum (0.70) and Indian bee, A. cerana (0.44). There were no significant differences among varieties with respect to pollinators associated with them. Peak foraging hours of A. florea were between 9 am and 11am with a second peak between 3 and 4 pm while that of dipterans were between 11 am and 3pm. Mean foraging time of A. florea per floret was 5-6 seconds per floret and foraging 4.5 florets in a single visit. Syrphids were quick fliers and spent only a mean time of 2-3 seconds per floret and covered 2.5 florets per visit. Twenty panicles in each variety were bagged with a nylon mesh before flowering. There was 80 -90% reduction in the fruit set of bagged flowers. It was evident that insect pollinators played significant role in fruit setting of mango. The present study identifies Apis florea and Chrysomya megacephala as the most potential pollinators of mango.

Host plant resistance to thrips in chrysanthemum: Appraisal of germplasm evaluation

Fri, 01 Jan 2010 00:00:00 GMT

Title: Host plant resistance to thrips in chrysanthemum: Appraisal of germplasm evaluation Authors: P, Venkata Rami Reddy; T, Janakiram Abstract: Chrysanthemum (Dendranthema grandiflora Tz.,) is one of the commercially viable flower crops of India and is popular among small and medium farmers. Thrips (Microcephalothrips abdominalis) are the most serious and economically important pests of chrysanthemum. Nymphs and adults lacerate the tissues of flower buds and flowers and suck the sap causing scorching marks and deformation. Severe incidence of thrips adversely affects the marketable flower yield thus making the frequent use of insecticides inevitable. In order to minimize the insecticide usage, a sustainable and ecologically viable pest management strategy like host plant resistance is very much needed. In our study, 80 germplasm collections of chrysanthemum were evaluated for resistance to thrips, at Indian Institute of Horticultural Research, Bangalore, India during 2006-09 and found significant variations among accessions in their susceptibility to thrips. We identified a few genotypes viz., Swetha Sringar, Varthur, Lemon, Co-2, Mother Teresa and Kargil which were least susceptible and could be further explored as resistance sources. Significant variations were also observed among three colour groups of flowers in attracting thrips viz.,. yellow, red and white. Varieties of yellow coloured flowers attracted highest number of thrips (12.24/flower) followed by red (5.12) and white (6.82) which were on par with each other. Comparative assessment of variability among indigenous and exotic collections revealed that the indigenous collections were more promising as resistance sources than exotic accessions indicating the priority the native germplasm deserves in screening for resistance. In the light of these findings, nature and scope of host plant resistance against thrips in relation to flower colour and origin of chrysanthemum accessions are discussed.