الفهرس 
Varietal effectOnly 14 pages are availabe for public view
 |  | from | 106 |  |  |
| | | from | 106 | | |
Abstract
The present investigation was conducted on the experimental station of Faculty of Agriculture, Tanta University, at Kafr El-Sheikh, Egypt, during 1990 and 1991 seasons, to study the effect of plant populations and nitrogen rates on growth, seed and oil yields and its components of two sunflower cultivars. The two cultivars (C) used were Mayak and Pioneer 6431. Plant populations (P) were 17,500, 23,33 and 35,OO plants/feddan. Nitrogen (N) rates were 0,20, 40, 60 kg nitrogen/feddan. A split-split plot design with four replications was used. The two cultivars were randomly allocated to the main plots, plant population to the sub plots and the nitrogen fertilization rates to sub-sub-plots. Samples of sunflower plants were taken at 50, 63 and 80 days after sowing (DAS) for growth analysis determination. The results obtained can be sumnarized as follows: A. Growth analysis: A.1. Dry matter accumulation: The cultivar Mayak accumulated significantly more dry matter than the cui~ivar-P ioneer 6Gi, except at 50 and 69 EAS In the first seasons. Dry weight per piant was significantly increased by decreasing plant population and increasing nitrogen rate at all sampling dates’ in both seasons. The interactions C x P. C x N and P x N had a significant effect. on this respect at most sampling dates in the two season.