Improving the growth and yield of black seed (Nigella sativa L.) by combining nitrogen and wheat straw mulch at different irrigation intervals

The appropriate amount of nitrogen consumption and the positive effects of wheat straw mulch in medicinal plants are important to reduce the negative effects of drought stress and achieve high yield.

In this study, the growth and yield of black seed by combining nitrogen and wheat straw mulch at different irrigation intervals. This research was conducted as a split plot in a randomized complete block design. The first factor is different irrigation intervals in three levels including 25, 50 and 75% moisture drainage and the second factor in six levels includes 50 and 100 kg of urea per hectare in combination with mulch and consumption alone, mulch and control.

Increasing irrigation intervals decreased the amount of leaf elements. Also, an increase in ion leakage and decrease in the relative leaf water content were observed in 75% of moisture depletion. Application of wheat straw mulch was able to reduce ion leakage of black seed under drought stress conditions. Urea was effective in increasing nitrogen uptake and as a result increased the amount of photosynthetic pigments. At 25% moisture discharge, shoot dry weight per 100 kg of urea with wheat mulch and consumption alone showed an increase of 8.7% and 7.1%, respectively, compared to the control. The highest harvest index and yield components were observed in the use of mulch in combination with urea.

In total, the application of 100 kg of urea per hectare in combination with wheat straw mulch for planting black seed is recommended.