Effectiveness of Colemanite Ore as Boron Source for Sunflower (Helianthus Annuus L.) Oil Content and Yield

Abstract

Sunflower is a very important oil seed crop and it’s per hectare yield in Pakistan is low in compare to genetic potential of crop.
The imbalanced nutrition is one of the major cause. Boron (B) deficiency affects plant flowering and seed formation. Two kinds of B
fertilizers are applied to the crops, the first type of B source are the refined completely soluble materials and the second type is crushed ore
such as colemanite (Ca2B6O11.5H2O) minerals, these are slow release and cheap B fertilizer but not widely used as B fertilizer. A glass
house study was conducted at the Sindh Agriculture Univesity Tandojam to assess the effect of colemanite as a source of B for sunflower oil
content and yield. The six levels of B at the rates of control 0 kg ha-1, 1.0 kg ha-1, 2.0 kg ha-1, 3.0 kg ha-1, 4.0 kg ha-1 and 5.0 kg ha-1) were
applied with four replications. At the time of sunflower sowing B fertilizer colemanite were applied. The results of the experiment had
shown that colemanite application improved agronomic parameters of crop at all B levels in compare to control. The maximum plant height,
number of achenes per head, stem diameter and achene yield were higher at 4 kg B ha-1 as at this rate and 5 kg ha-1 B levels difference was
not significant. The B application in the shape of colemanite at the rate of 4 kg B ha-1 was found optimum for better sunflower yield and oil
content. The B content in post-harvest soil samples was high in colemanite applied pots and it is showing that B residual effect on
subsequent crop will be positive. It has been concluded that colemanite is an effective and cheaper source of B for sunflower and can be
used for higher yield and better oil content.