ECONOMIC STUDY ON ONION SEED PRODUCTION FROM SETS UNDER DIFFERENT PLANT SPACINGS AND NITROGEN LEVELS

The aim of this study is to use the sets for onion seed production instead of traditional use of large mother bulbs. Two field experiments were carried out in 1997-98 and 1998-99 on the Farm of the Agricultural Research Station, at Sids, Beni-Suif Governorate, to study the effect of three plant spacing, sets at 10,12.5 and 15cm. and three levels of N (90,120and 150 kg/fad).A split plot design with three replication was used in this investigation. the obtained results can be summarized as follows:
                *Number of sprouts per plant was significantly affected in both seasons by two factors .The increasing of spaces between sets increased the number of sprouts /plant in the both seasons(2.03,1.99 respectively), also the lowest level of nitrogen fertilizer gave the lowest value of this character during he two successive seasons(1.76,1.72 respectively).
*Seed yield / umbel, was effected by both factors and their interaction between the two factors was significant in both seasons. The increases of spaces between sets and the increasing nitrogen fertilizer gradual increase in seed yield / umbel. The higher space with the higher level of nitrogen fertilizer gave the highest seed yield per umbel (6.93 gm) in the two seasons.
*Seed yield /plant, increased with increase of spacing and increasing N rate and the interaction in both seasons were significant. Planting sets at wider space gave the highest value of this trait 14.28 gm in the first season and 14.21 in the second one. While the higher rate of nitrogen fertilizer produced 13.48 and 13.57gm/plant in the first and second seasons respectively. Meanwhile, the highest seed yield per plant was produced from planting sets at 15 cm apart with 150kg /fadd. (15.23gm/pant and 15.50 gm /plant in the first and second seasons respectively.
*Seed yield per feddan gradually decreased with increasing the spacing of planting sets from 10, 12.5 up to 15 cm. Also there was gradually increased with increasing the rate of nitrogen fertilizer from 90kg / fadd. to 150 kg / fadd. The highest total seed yield per fadd. was produced through the combination of highest rate nitrogen fertilizer (150 kg /fadd.) with the highest plant density (623.7 in the first season and 619 kg/faddan in the second one).
*Economic evaluation, the highest value of Gross Margin with 10 cm Spacing and 150kg N/fadd. While the highest value for the Benefit Cost (B/C) ratio (10 cm Spacing and 120 kg N/fadd.).
                According to the results we recommended that the sets are useful and use the closer spacing (10cm) to obtain high of seed yield /fadd., gross margin and benefit cost ratio.