MSc

Artocarpus heterophyllus Lam, belonging to the family Moraceae and popularly known as jackfruit tree, is one of the important timber species commonly found in the homegardens of Kerala. The main objective of the present study was to identify plus trees of Artocarpus heterophyllus from Thrissur and Palakkad districts and to evaluate their seedling growth performance for quality timber production.

Forty plus trees, twenty each of varikka and koozha variety were selected from both districts. Seedling biometric observations like stem height, collar diameter, leaf area, fresh weights and dry weights of stem, leaves and root showed significant differences throughout the study period, i e from 30 DAP (Days After Planting) to 150 DAP. At 150 DAP, seedling height ranged from 123.10 cm (FCV AH 22) to 68.35 cm (FCV AH 1) and collar diameter ranged from 14.39 mm (FCV AH 8) to 7.18 mm (FCV AH 7). At 150 DAP, FCV AH 4, FCV AH 22 and FCV AH 15 had the highest value for both fresh weight (33.88 g, 25.22 g and
25.25 g) and dry weight (16.41 g, 8.26 g and 8.54 g) of stem, leaf and root respectively. Other parameters like taproot length, number of leaves, Leaf Area Ratio, Specific Leaf Area, Absolute Growth Rate, Relative Growth Rate and Net Assimilation Rate were also found to be significant but not throughout the study period. The highest taproot length was noticed in FCV AH 2 (48.85 cm) and the least taproot length was in FCV AH 14 (30.45 cm) at 150 DAP.

To establish a field trial plot, seedlings were out planted one year after nursery growth near the International Hostel at KAU, Vellanikkara. Field performance of the progenies were evaluated at 30 DAP. Seedling height and collar diameter were found to be significantly different among various seed sources. The average seedling height was 117.30 cm with values ranging from 143.94 cm to
96.35 cm and FCV AH 22 being the tallest. The mean collar diameter was

12.27 mm with FCV AH 29 having the highest (14.67 mm) value.

Hierarchical cluster analysis based on the morphological and biometric characters was carried out and 40 plus tree sources were grouped into twenty-one



clusters. Based on the biometric observations for 150 DAP and cluster analysis, it was found that Cluster 2 (FCV AH 2), Cluster 18 (FCV AH 8), Cluster 12 (FCV AH 9), Cluster 11 (FCV AH 15), Cluster 10 (FCV AH 21), Cluster 21 (FCV AH 22), and Cluster 15 (FCV AH 23) possess superior quality.

Anatomical studies of young (six month old) Artocarpus heterophyllus seedlings from different seed sources and core samples of mature trees from a ‘Jack Gene Sanctuary’ of the Agricultural Research Station (ARS), KAU at Mannuthy revealed significant differences in various parameters. Vessel area, ray height, ray width, fibre length and fibre wall thickness were found to be significantly different in six month old seedlings, whereas samples from mature trees showed significant difference in vessel diameter, vessel area, vessel frequency, ray height and ray width. Mean vessel area increased from 4199.14 µm2 in young seedlings to
62569.05 µm2 in mature trees. Mean vessel diameter also increased from

126.43 µm in young seedlings to 276.58 µm in mature trees. Mean ray height and mean ray width were found to be 466.98 µm and 34.58 µm in young seedlings and
498.38 µm and 52.97 µm in mature trees respectively. Mean fibre length and fibre wall thickness were found to be 801.13 µm and 3.27 µm in young seedlings and
993.10 µm and 4.37 µm in mature trees

Questionnaire survey conducted in Thrissur and Palakkad district had

46.34 per cent and 39 per cent positive response respectively towards growing jack tree as a timber species in homegardens. There is an increasing preference for dwarf varieties over tall indigenous varieties among the respondents in both districts. The increasing trend of planting dwarf varieties can have an adverse effect on the easy availability of good quality wood from our homesteads. Therefore, there is a pertinent need to protect the existing high quality tall varieties of jack trees.