1. YIELD AND YIELD COMPONENT ANALYSIS OF ONION CULTIVARS GROWN IN ARID REGIONS ABDULLAH A. ALSADON Department of Plant Production, College of Agriculture, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia

2. INTRODUCTION

3. OBJECTIVES * To evaluate yield performance of eleven onion cultivars under the arid conditions of Riyadh area. * To determine yield stability differences among onion cultivars.

4. MATERIALS AND METHODS

5. Cultivar performance trial * Eleven onion cultivars were used ( Table 1 )  Study conducted at the Agricultural Research and Experiment Station of the College of Agriculture, at Dirab near Riyadh, Saudi Arabia during the 1997 and 1998 seasons.  The temperature and relative humidity data were recorded.  Transplants were grown under greenhouse conditions for 45 days.

6. * Transplanting was carried out on 7 January 1997 and on 29 December 1997 for the first and second seasons, respectively.  The field layout was a complete randomized design with three replications.  Plots consisted of nine rows, each 3 m long and.7 m wide. The distance was 15 cm between plants and 75 cm between rows.  Common cultural practices were performed.

8.  Harvesting was carried out on 19 May 1997 and on 15 May 1998 for the first and second seasons, respectively.  Yield and yield components studied: Yield (ton/ha) Bulb weight Bulb diameter Bulb length Dry matter  Yield stability analysis was assessed.

9. RESULTS AND DISCUSSION

10. * Significant differences between cultivars and among growing seasons. * Significant cultivar x season interactions were significant for mean yield and other yield traits.

11. Fig 1. Yield of eleven onion cultivars as influenced by growing season. See table 1 for full listing of cultivars.

12. Fig 2. Bulb weight of eleven onion cultivars as influenced by growing season. See table 1 for full listing of cultivars.

13. Fig. 3. Bulb diameter of eleven onion cultivars as influenced by growing season. See table 1 for full listing of cultivars.

14. Fig. 4. Bulb height of eleven onion cultivars as influenced by growing season. See table 1 for full listing of cultivars.

15. Fig. 5. Dry matter of eleven onion cultivars as influenced by growing season. See table 1 for full listing of cultivars.

17. RM DR RM RC RM b i >1 Fig. 5. Dry matter of eleven onion cultivars as influenced by growing season. See table 1 for full listing of cultivars.

18. CONCLUSIONS