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Work done byCoconut Research Institute, Sri Lanka, on the genetics and breeding of the coconut palm from 1930 to 1980 is described. It involves studies on: mass selection methods, selection differential, progeny trials, inbreeding depression, estimation of genetic parameters, construction of selection indices and varietal hybridization. Two improved varieties CRIC 60 and CRIC 65 have been produced. An isolated seed garden was established for the large scale production of seed of the improved varieties. INTRODUCTION The Coconut Research Scheme in Sri Lanka was established in 1929, under the Coconut Research Ordinance, No. 29 of 1928. There were three divisions then: technology, genetics and soil chemistry. There was only one scientific officer attached to each division. The genetics division functioned from 1930. Subsequently, the Coconut Research Scheme was upgraded and enlarged into the Coconut Research Institute (CRI) in 1951 with more divisions and scientific staff. The present report covers the work done by CRI on coconut breeding from 1930 to 1980. Those who were in charge of the Division during this period are indicated below. The emphasis on the nature of breeding work varied with the Heads of Division: Pieris concentrated on mass selection, Raghavan on a progeny trial; Liyanage on genetic parameters, controlled pollination and production of improved varieties; Manthriratne on assessment of performance of hybrids.

The compensation heat pulse method (CHPM) was used to determine the diurnal variation and daily total water use of two coconut varieties (i.e. CRIC 60 and CRIC 65) growing on two contrasting land suitability classes (i.e. S2, Kurunegala series, and S4, Kuliyapitiya series) in the lowcountry intermediate zone (IL1) of Sri Lanka. The average daily total sap flow (F d) of CRIC 60 and CRIC 65 on S2 were 120 and 90 L d-1 while on S4 it was 92 and 79 L d-1 respectively. Palms on S2 showed higher F d than those growing on S4, with 27% and 15% increases in CRIC 60 and CRIC 65 respectively. The greater soil depth and the water holding capacity of S2 and the consequently greater trunk water storage of palms growing on S2 were the probable causes. CRIC 60 showed 24% and 22% greater F d than CRIC 65 on S2 and S4 respectively. On S4, this was primarily because of the higher leaf area per palm of CRIC 60. On S2, both varieties had similar leaf area, indicating that varietal differences in root water absorption and stem water conductance capacities were probably causing the varietal difference in F d. On the majority of measurement days, all palms reached their maximum hourly sap flux (F m) after 1000 h, maintained it until 1600 h followed by a rapid decline. F d showed a strong positive correlation with F m. A significant positive correlation between daily total sap flow and total leaf area per palm provided strong validation to the results obtained.

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Among the tree crops in the tropics the coconut palm occupies an important position as a food, oil, and fibre crop. Productivity of crop species depends on the combined effect of their genetic constitution, climate, nutrition and other biotic factors. To increase the productivity of the coconut palm it is necessary to have a basic understanding of physiological processes such as assimilation of carbon and growth in relation to climatic factors.In-situ photosynthetic measurement of coconut seedlings using Li-COR 6500 portable photosynthesis system revealed that their maximum photosynthetic capacity is attained at photosynthetic photon flux densities (PPFD) ranging from 1400-1700 u moles photons m' 2 S" 1 . The rate of apparent photosynthesis (A) of the coconut palm varies between 2-15 a moi C0 2 m" 2 S" 1 depending on leaf age, nutritional status .and climatic factors. The rate of leaf respiration was closely similar in young and older leaves ranging from -2 to -1 fi mol C0 2 m' 2 S"'. The measured light-use efficiency of the coconut palm was found to be 1.2 g MJ" 1 and the conversion efficiency of solar energy was approximately 2.4%.Water deficit is the major constraint causing wide fluctuations in photosynthesis. Due to height of trees, the leaves in the canopy are exposed to a high wind velocity as well as water and thermal stresses. As a result, under soil water deficit conditions coconut palms reduce excessive water loss and gaseous exchange by mid-day closure of stomata and maintain stomatal conductance at a lower level. However, the rate of apparent photosynthesis and the ratio of intercellular to ambient partial pressure of C0 2 (P/PJ are not decreased proportionately with the stomatal conductance.