http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/647 Tue, 28 Apr 2026 08:06:45 GMT 2026-04-28T08:06:45Z http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/884 EFFECT OF SOIL PHYSICAL AND WATER STRESS ON BIOCHEMICAL ASPECTS OF COCONUT SEEDLINGS (Cocos nucifera L.) IN SRI LANKA Vidhana Arachchi, L.P; Vidhana Arachchi, V.R.M; Epasinghe, E.S.P Soil physical and water stress conditions adversely affect the biochemical aspects of coconut production. Field experiments were conducted in Madampe and Andigama soil series, to investigate the ATPase activity, starch conversion to glucose and accumulation of proline in leaves, absorption cells and respiratory organs of coconut roots and their interrelationships with respect to soil physical and water stress. After one and half years of the establishment of coconut seedlings in different horizons of both series, the moisture contents at three depletion levels viz.10 kPa to 30 kPa, 10 kPa to 100 kPa and 10 kPa to 1500 kPa were maintained using tensiometers and neutron scatteringtechnique in order to create moisture stress around root zone of coconut seedlings during the dry period. Detailed soil physical analysis showed that soil compaction limits the aeration and available water retention in soil horizons of both series. Evaluation of biochemical properties showed that the highest ATPase activity and starch conversion to glucose in leaves and absorption zone of coconut roots was observed in the B horizon of Madampe series at field capacity moisture level (10 kPa to 30 kPa suction), while the lowest activity was observed in the A horizon of Madampe series and B horizon of Andigama series at high water stress condition (100 kPa to 1500 kPa suction). However, the highest ATPase activity and starch conversion rate was observed in respiratory organs in A horizon of Madampe series. Moreover, the starch and proline accumulation in different parts of coconut seedling positively related with soil physical and water stress conditions (100-1500 kPa) prevalence in ‘A’ and ‘B’ horizons of Madampe and Andigama series respectively. Sat, 01 Sep 2012 00:00:00 GMT http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/884 2012-09-01T00:00:00Z http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/880 PRESENCE OF PHEOPHYTIN AND ITS FORMATION AS A CHLOROPHYLL DERIVATIVE IN SELECTED CROP SPECIES Dissanayake, P.K; Yamauchi, N; Shigyo, M Most of the green leaf vegetable and fruits lose their postharvest quality mainly due to yellowing as a consequence of chlorophyll (Chl) degradation. The study of Chl degradation of many plants have been revealed that the Chl degradation mainly progress through formation of chlorophyllide (Chlide) a. Recent studies have revealed that the Chl degradation could be progressing through formation of pheophytin (Phy) a as a Chl derivative. Present study was conducted to investigate the presence and formation of Phy a as Chl a derivative in selected stored plant species. Green tea leaves, bell pepper, parsley and Japanese bunching onion were used in the study. Presence of Chl a derivatives of 80% acetone extract of green tea leaves and Japanese bunching onion were detected using HPLC at the wave length of 663nm. Formation of Chl a derivatives were studied by incubating crude enzyme extract of bellpepper, parsley and bunching onion with Chl a and buffer solution. After one hour of incubation reaction was stopped by adding 80% acetone. Chl a derivatives were studied using HPLC at 663nm. Phy a level of processed green tea leaves was very high when compared to other plants. In parsley, bellpepper and Japanese bunching onion formation of Phy a was prominent. All these indicated that early studies of Chl degradation need further study to elucidate the mechanism of Chl degradation in green plants. Sat, 01 Sep 2012 00:00:00 GMT http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/880 2012-09-01T00:00:00Z http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/879 GENETIC AND EVOLUTIONARY RELATIONSHIP AMONG NICOTIANA SPECIES AS ELUCIDATED BY AFLP Siva Raju, K; Sharma, R.K; Murthy, T.G.K Twenty two species representing three subgenera of the genus Nicotiana and two interspecific hybrids were analysed by AFLP. A total of 554 bands were amplified by 6 primer pairs, of which 541 (97.65%) were polymorphic and 13 (2.34%) monomorphic. The primer combination E-AAC/M-CTG gave the highest polymorphic information content (PIC) across all species, whereas E-AAG/M-CAC gave the lowest PIC score. A total of 59 species specific markers were generated, of which 54, 4 and 1 were specific to subgenera Petunioides, Tabacum and Rustica respectively. The pair-wise similarity measure in the species of subgenus Rustica was 0.35 whereas it was 0.29-0.50 in subgenus Tabacum, suggesting that there was significant diversity among the species of these subgenera. In the species of subgenus Petunioides, the range of pair-wise similarity measure was 0.25 to 0.95. The high genetic similarity (95%) was due close relationship among the species belonging to the sections Rependae and Trigonophyllae. Sub-grouping of the species within the main clusters of dendrogram was largely based on the chromosome number. AFLP was found efficient in determining the extent of interspecific genetic diversity existing in genus Nicotiana. The subgenus and species specific AFLP markers identified in this study would be useful in introgression breeding programs of tobacco. N. tabacum shared 174/198 AFLP fragments with the two progenitor species, thus providing molecular evidence that these two wild species contributed genetic information to N. tabacum Sat, 01 Sep 2012 00:00:00 GMT http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/879 2012-09-01T00:00:00Z http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/875 EFFICIENCY AND MANAGERIAL ABILITY OF PADDY FARMING UNDER MINOR IRRIGATION CONDITIONS: A FRONTIOR PRODUCTION FUNCTION APPROACH Aruna Shantha, A; Asan Ali, B.G.H; Bandara, R.A.G In economics, it is well recognized that resources involved in the production process are limited in supply and the scare resources should be efficiently used without wasting. Efficient utilization depends on managerial ability of entrepreneurs-farmers, firm, etc. Available literature suggests that farmers in the developing countries fail to exploit the full potential of a technology and make allocative errors. Thus, increasing the efficiency in production assumes greater significance in attaining potential output at the farm level. However it is an undeniable fact that the majority of dry zone paddy farmers are characterized by poor economic status due to inefficient utilization of available resources. This paper investigates the economic and technical efficiency of paddy farming in a minor irrigation scheme in Sri Lanka and to suggest some policy recommendation for improving the efficiency of resource use.The experiment sites were four minor tanks in Tricomalee district and respective tanks were randomly selected based on the list of the village tank in same district. The empirical study was carried based on a sample of 158 farmers in selected tanks. In this study, the technical efficiency of paddy farmers was estimated by using stochastic frontier production function, incorporating technical efficiency effect model. The Cobb Douglas production function was found to be an adequate representation of the data.According to the results obtained from the stochastic frontier estimation, the average technical efficiency of selected farmers given by the Cobb Douglas model is 69.08 per cent. This indicates that there is scope of farther increasing the output by 30.2 percent without increasing the level of input. With imputed cost profit margin of paddy farming under village tanks was Rs.0.27 per kg and Break even yield was 3,505 kg per ha.The analysis using the Cobb-Douglas function indicated miss-allocation of resources in most of the location in the sample area due to managerial inability of farmers. Sat, 01 Sep 2012 00:00:00 GMT http://repo.lib.sab.ac.lk:8080/xmlui/handle/123456789/875 2012-09-01T00:00:00Z