Improving the Achene Yield, Oil contents and Nutrient uptake in Spring planted Sunflower (Helianthus annuus L.) by potassium application.

Drought stress hampers the alllometery and yield of crop plants. Owing to its significant role in osmoregulation, potassium can be used to induce the drought tolerance in sunflower. A three years field study was carried out at Agronomic Research Area, University of Agriculture, Faisalabad, Pakistan during 2005-07 to explore the role of potassium in improving the performance of sunflower under drought stress. Drought stress was imposed by withholding irrigation at pre-anthesis, anthesis and post anthesis stages. Whilst, well watered was taken as control. Potassium was applied at 0, 50,100 and 150 kg ha^-1 as basal dose in the form of sulphate of potash. Drought stress at either stage significantly reduced achene yield, oil contents and NPK uptake. Nonetheless stress at pre-anthesis was more damaging nevertheless stress at post-anthesis minimally affected the crop performance. Achene yield and oil contents were out-yielded at normal irrigation with 150 kg ha^-1 potash. Nonetheless, potash application at 150 kg ha^-1 significantly (32%) improved the achene yield at post-anthesis stress compared with no potash application. Achene yield, allometry, oil and protein contents were strongly correlated with NPK uptake. In crux, potash application can improve the drought stress in sunflower if applied at higher rate.