PhD

The project entitled “Diversity mapping and characterization of landraces of mango [Mangifera indica. L]” was undertaken at Pazhayannur region of Thrissur district of Kerala and under the department of Pomology and Floriculture, College of Horticulture,Vellanikkara, KAU during November 2012 to March, 2016. Selection of Pazhayannur region as the site of the present studies was based on a primary assessment conducted in this region earlier. The present investigations broadly envisaged the diversity mapping and digitization of mango LRs of this region, their characterisation, preparation of diversity registers and descriptors, documentation of associated indigenous traditional knowledge (ITK) and evolving appropriate integrated conservation and improvement strategies for the rare LRs spotted during the project implementation.
Snow ball sampling method was used for locating the seedling mango LRs in different villages of the region and their spatial distribution was depicted through a series of GIS maps as per the geo co-ordinate readings. A total of 100 LRs could be thus located in the region and could be grouped in five GIS maps primarily based on their geographical position and further into the different rural hamlets of the major villages of the study site. A homestead based land use practice was largely noted in all these villages surveyed with many annual and perennial species planted and maintained around the homesteads where mango diversity confining to the homestead peripheries either as single plant or a component of poly crop system.
The morphological characterization was carried out as per the standard descriptor for mango by IPGRI (2006) for different tree, leaf, inflorescence, fruit and biochemical parameters.
Age of the trees surveyed spanned over a range of less than 20 years to more than 100 years and the trees were erect, spreading or drooping in their growth habit. A wide variation among the young leaves was noted with respect to the colour and it varied from light green, light green with brownish tinge, light brick red, reddish brown, and deep coppery tan. Flowering was noted from November to March making into early (November to December), midseason (January to February) and late season (from March) as noted among the different accessions and two intermediate periods between the seasons. Regular bearing was predominantly noticed in majority of the accessions but for few accessions which exhibited secondary/perpetual type of flowering. All most all the accessions produced terminal borne inflorescences but few accessions showed axillary and terminal emergence of inflorescence. The inflorescences were predominantly pyramidal in shape, followed by broadly pyramidal and conical in few. Inflorescence colour ranged from light green to crimson.
Based on maturing period, the trees could be classified as early - if the fruits become mature for harvest by February, as intermediate - if ready for harvest by March to May, and as late - if ready by June. For pickling purpose, the stage for harvest varied from marble stage (for Kadu/tender manga pickle), to pre-mature (three-fourth) mature stage for Chethu manga.
Fruit shapes varied from round, elliptic, obovoid, ovoid and oblong. Fruit colour was distinct and as a rare occurrence brownish colouration of the skin could also be noted in one of the accessions. Fruit weight varied from 44 g. to 634.82 g., pulp weight from 19.80 g to 419.50 g. and the thickness of the skin from 0.55 mm to 4.5 mm. With respect to the pulp colour, a great variation was observable viz., light yellow, yellow, yellow orange, light orange, dark orange, and greenish yellow. Presence of fibre in the fruit pulp was a unique feature of all the accessions. Pulp aroma was mild, intermediate or strong. Turpentine flavour which interferes with the edible quality of fruit was also noted in few . TSS of the ripe fruits varied from 7.6 to 23.65°brix and acidity from 0.1 to 1.49 percent.
Polyembryony was also notable in few accessions with emerging seedlings per stone ranging from two to four.
Principal component analysis and cluster analysis was carried out culminating in constructing a mathematical base for the entire survey.
Four cell participatory analysis (FCA) conducted at the different villages, enabled the confirmatory identification of the common and rare mango LRs of thevillages primarily and the region as a whole.

Overall diversity assessment clearly noted the predominance of the type Moovandan throughout the entire Pazhayannur region. Among the different villages maximum number of rare landraces could be spotted in Elanad village (39) followed by Vennur (19), Pazhayannur (19) and Vadakkethara (12). Accessions spotted from the extended locations of the survey (Tiruvilwamala and Panjal) were also added in to the rare group.
ITK associated with these mango LRs with special reference to the conventional and traditional processing of fruits were also documented.
A conceptual model for in situ conservation of the spotted LRs for the region could also worked out finally and a comprehensive village diversity register of mango LRs of the region in the specified format was prepared as a material for future reference.
Initiatives were also taken up for the ex situ conservation of some rare mango LRs spotted. Scion material of rare LRs was collected and grafted plants prepared for planting in the mango gene sanctuary maintained by the department.
Crossing and hybridization were also taken up during the project period involving selected LRs of the region as male parents with Moovandan and Neelum types maintained at the orchard of the college as female parents.