Abstract:
A field experiment was carried out to investigate the effect of combination of organic nitrogen
(Org.N) and inorganic nitrogen (Inorg.N) sources and spacing on plant growth and yield of tomato
(var. Thilina). The treatments were arranged in a randomized complete block design with three
replications. Each plot size was 4 m × 4 m. As per the recommendation of the Department of
Agriculture (DOA) Sri Lanka, 90 kg/ha of nitrogen was provided through different combinations of
organic and inorganic fertilizers.
Different combinations of nitrogen sources (N1- ¾ part of Inorg.N + ¼ part of Org.N, N2- ½ part of
Inorg.N + ½ part of Org.N and N3- ¼ part of Inorg.N + ¾ part of Org.N) and spacing (S1- 80 × 35 cm,
S2 - 80 × 50 cm as per the DOA recommendation and S3- 80 × 80 cm) were arranged in a two factor
factorial design. Required amount of Org.N was provided through compost as basal dressing. Other
major nutrients viz. phosphorus and potassium were supplied through inorganic fertilizers. The
parameters of plant height, leaf area, plant biomass and fruit yield were measured and data were
analyzed by ANOVA using SAS.
Different levels of nitrogen sources and spacing had a significant effect (p < 0.05) on plant height, leaf
area and plant biomass at harvesting stage and fruit yield of tomato. The interaction effects of nitrogen
sources and spacing on leaf area, biomass and fruit yield were also significant (p < 0.05). Plants
belonging to treatment N1S3 produced significantly higher leaf area (1450.78 cm2 per plant) while
plants belong to N1S1 produced higher plant biomass (2648.70 kg.ha-1) and fruit yield (27.93 t.ha-1)
than the others. Leaf area per plant showed higher response to inorganic nitrogen and wider spacing.
However, application of ¾ part of inorganic and ¼ part of organic levels of nitrogen planted at the
spacing of 80 × 35 cm could increase the productivity of tomato with reduced level of inorganic
nitrogen in the sandy soil of the Eastern region of Sri Lanka.
