ABSTRACT
Tomato (Lycopersicon esculentum Mill) is an important fruit vegetable crop all over the world including Nigeria. Its production level has increased in the last 10 years as a result of increased land area under cultivation and improved management practices. Research in the area of physiological determinants of fruit yield in tomato needs to be enhanced as information in this area is hitherto scanty. Growth analysis studies were conducted for two wet seasons and two dry seasons between 1989 and 1992 to determine the relationship between fruit yield and plant growth indices and to determine genotype responses and differences in growth and dry matter accumulation and distribution. Other areas covered in the study are determination of seasonal influence on dry matter accumulation and distribution. The use of simple and fast leaf rectangular area method in leaf area determination was also examined, and aspects,of the tomato plant growth that could be used as selection indices in crop improvement programmes were examined. Trials were cited at Samaru (11° ll1 N, 07° 38'E) and five genotypes of tomato viz SAMTOM-7 SAMTOM-10, SAMTOM-16, TI-244 and TI-468 were used in all trials. Sampling at weekly intervals, for six weeks starting from three weeks after transplanting was done for the determination of growth indices through leaf area and dry weights. Results showed that specific growth indices values varied between years and were closely related within season (wet and dry) . Thus environment was viewed to have had a great influence on all growth indices determined. Genotype difference in growth indices per sampling time was not significant. Net assimilation rate and mean crop growth rate significantly differed between genotypes, in each of the two dry seasons. Total plant dry weight was higher in the wet season than in the dry season but this had no direct relationship with fruit yield. The leaf area index (LAI), stem weight ratio, and root weight ratio had significant linear relationship with fruit yield. A high LAI would result in high fruit yield during the dry season but an optimum LAI was not attained. Leaf loss due to fungal attack prevented the establishment of a similar relationship during the wet season. A high correlation was observed between leaf rectangular area (LRA) and measured leaf area and the use of LRA in leaf area determination is thus considered suitable. Given the controlling influence of the environment on growth parameters determined in the study, it was suggested that recommendations resulting from growth analysis studies should always define the environment of the study. The need to establish an optimum LAI for high fruit yield in tomato was emphasized because of the observed significant association of the former with fruit yield. The growth parameters determined indicated that the leaf area index level would determine fruit yield in the tomato crop.
