Abstract:
Haramaya University had developed Haramaya I carrot variety which does not require vernalization for seed production, However, rates of blended NPS fertilizer and plant population were not determined to produce high seed yield and quality from the variety. This research was conducted to determine the effect of blended NPS fertilizer rates and plant spacing on yield and quality of carrot seed, and to estimate the cost-benefit of blended NPS fertilizer rates in carrot seed production. The field experiment was conducted in randomized block design (RCBD) with three replications, which consisted of five levels of blended NPS (0, 75,100,125 and 150 kg ha-1), three inter-row spacing (75, 85 and 95 cm) and two intra-row spacing (25 and 30 cm) in factorial combination. The laboratory experiment was conducted in complete randomized design (CRD) with four replications. The results of analysis variance indicated the significant effect of blended NPS fertilizer on all seed yield, yield related and seed quality traits except duration to fruit set. Inter-and intra-row spacing had also significant effect on all growth and seed yield and yield components except the nonsignificant effect of intra-row spacing on number of secondary umblets. Inter-and intra-row spacing had significant effect on shoot length of seedling, root length of seedling, seedling dry weight, seedling vigor index one and two. Inter-row spacing had significant influence on percentage of pure seed, inert matter, seed moisture content, germination of seeds of secondary umbels and speed of germination. One or more of the possible two main factors interactions (NPS fertilizer x intra-row spacing, NPS fertilizer x inter-row spacing and intra x inter-row spacing) and the three factors interaction (NPS fertilizer x intra x inter-row spacing) had significant effect on most of the growth, seed yield related and seed quality traits, However, none of the possible interactions had nonsignificant effect on all phenology, seed yield, seed weight, germination and speed of germination traits. The highest seed yield of 1014.686 and 965.763kg ha-1 obtained from plot that received 150 and 125 kg ha-1 NPS fertilizer, respectively, whereas the higher seed yield of 901.032 and 995.718 kg ha-1 obtained from plants spaced at 95 and 30 cm inter and intra-row spacing, respectively. The performance of the variety was higher for other growth seed yield and seed quality traits in plots which received 150 and 125 kg ha-1 NPS fertilizer, and intra-and inter-row spacing of 30 and 95 cm, respectively. The application of 150 kg ha-1NPS fertilizer in combination with plants spaced at 85x30 cm that had highest MRR of 142.66 (14266.29%) but allowed the seed producer to obtain second highest net benefit( 1341856.00 ) and the application of 150 kg ha-1NPS fertilizer with combination of plants spaced at 95 x30 that allowed the producer to obtain highest net benefit (1361884 Birr) but allowed to obtain the 5th ranking MRR(103.53 ) .The possible two and three main factors had significant effect on most of the growth, seed yield, yield related and seed quality traits, therefore, it is necessary to conduct the experiment at xv least for one season to draw a final recommendation. Therefore, the application of this treatment combination could be recommended to produce high seed yield without comprising the seed quality of Haramaya I. The possible two and three main factors had significant effect on most of the growth, seed yield, yield related and seed quality traits, therefore, it is necessary to conduct the experiment at least for one season to draw a final recommendation.