RESPONSE OF SUNFLOWER (HELIANTHUS ANNUUS L.) TO PHOSPHORUS AND NITROGEN FERTILIZATION UNDER DIFFERENT PLANT SPACING AT NEW VALLEY

ABSTRACT:
This investigation was carried out in the New Valley Agricultural Research Station
during the summer growing seasons 2007 and 2008 under drip irrigation system to study
the effect of phosphorus and nitrogen fertilizer levels and plant spacing on growth, yield
and yield components of sunflower (var. Giza 102). The plant spacing of 10, 20 and 30 cm
were used for the study. Phosphorus and Nitrogen levels were 15, 22.5 and 30 kg P2O5 fed-1
& 30, 45 and 60 kg N fed-1, respectively.
The obtained results revealed that increasing phosphorus fertilizer levels from 15 to 30
kg P2O5 fed-1 significantly increased all parameters under study. Plant spacing had
significant effects on sunflower growth characteristics. The highest plant height seed and
oil yields kg fed-1 obtained from narrow spacing between plants (10 cm). The highest stem
and head diameter, 100-seed weight, seed husk, oil% and seed yield per plant recorded at
wide spacing (30 cm). Nitrogen application markedly enhanced growth and yield, but
resulted in decrease in seed oil percentage. Application of 60 kg N fed-1 produced the
highest seed and oil yields fed-1.
Considering the superiority of 30 kg P2O5 fed-1, 10 cm plant spacing and 60 kg N fed-
1for seed and oil yield, it appears that it could be recommended for producing desirable yield
under the New Valley soils conditions.