Vikraman Nair, RKurian AbrahamKAU2019-05-082019-05-081993170479http://krishikosh.egranth.ac.in/handle/1/5810102386PGA study on light infiltration through coconut canopies was conducted utilising measurements from different locations in Thrissur, Kottayam, Kasargod and Kannur districts during the period from July 1992 to April 1993. The main objectives were to assess the light infiltration through coconut canopies of different homestead situations varying in height, spacing and canopy characters of palms, to assess the relative influence of the measured crop parameters and to develop a model to predict light infiltration from these parameters. A total of 113 observations were taken. Each observation included measurement of light intensity from 10 a.m to 4 p.m. using line quantum sensor in the centre of four palms and point quantum sensor in the open. Simple correlation and multiple regression analyses were made to correlate all the measured independent variables with light infiltration. The important results from the study were the following. The daily mean values of light infiltration in different situations ranged from 7 to 86 percent. A total of 58 per cent of the situations had light infiltration in the range from 10 to 40. Of the various measured parameters, the relationships of average crown diameter and average number of leaves with light infiltration were negative and with east – west distance of planting and area occupied by a palm, positive. The remaining two parameters, north – south distance of planting and average height of palm did not show significant correlation. The turning point of quadratic model relating light infiltration with plant height was found to be 6.4 indicating that the light infiltration decreases with increase in plant height upto this height of 6.4 meters there being a reverse trend beyond this height. The approximate age corresponding to the turning point was estimated as nine years. The decrease in light infiltration with increase in height in the early years is explainable as there will be a corresponding increase in canopy size and density. The decrease in it, on the contrary, may be due to decrease in effective canopy size. Prediction equations were developed to predict light infiltration from the measured crop parameters. Multiple linear equation relating light infiltration with average height of palms, crown diameter, east-west distance and height – square was worked out. This gave a predictability of 72 per cent. Through a serious of improvements involving selection of better models and elimination of add values, a multiple curvilinear regression equation was arrived at which had a predictability of 82 per cent. The results of the present study are in marked deviation from the earlier report by Nelliat et al. (1974) with age/hight showing much less dependence on light infiltration. It is concluded that it may be difficult to predict light intensity of interspaces of coconut with accuracy using this parameter only.ennullThesis