Evaluation of the yield, yield components and content of photosynthetic pigments of Plantago ovata in response to phosphorus fertilizers and planting method under drought stress

Today, the use of medicinal plants has grown considerably due to the reorientation of human towards nature and natural products, the side effects of synthetic materials and the discovery of new drugs from the nature. Water scarcity is one of the important environmental factors for reducing the growth and yield of many crops, especially in the arid and semi-arid regions of the world. After nitrogen; phosphorus is the most important essential nutrient required by the plants and different seed position in the soil can affect plant growth. Therefore, an experiment was conducted to study the effect of the planting method and phosphorus fertilizers in response to drought stress on the yield, yield components and photosynthetic pigments of isabgol (Plantago ovata L.).

This experiment was performed as a split-factorial in the form of a randomized complete block design with three replications in the research farm of Zabol University located in Chah Nimeh. The experimental treatments were including three drought stress, irrigation after 60, 120 and 180 mm evaporation from a class A evaporator as the main-factor, and the combination of seed planting method (flat or ridge planting) and the types of phosphorus fertilizer (100% chemical phosporous fertilizer, Phosphate Barvar2, and 50% chemical phosporous fertilizer + Phosphate Barvar2) as the sub-factor.

The vairiance analysis showed that the interaction of drought stress and phosphorus fertilizers were significant on on number of spikes per plant, number of seeds per spike, 1000-seed weight, grain yield, carotenoids, and total leaf chlorophyll, mucilage percentage and seed swelling index. The greatest spikes per plant, number of seeds per spike, 1000-seed weight, grain yield and total leaf chlorophyll were obtained in conventional irrigation treatment along with the combined application of chemical phosphorous fertilizer and Phosphate Barvar2, while, the highest data for carotenoids (0.78 mg. g-1 FW) and mucilage percentage (15.04 %) were obtained in severe drought stress along with combined application of chemical phosphorous fertilizer and Phosphate Barvar2. Based on the results; the amount of proline and carbohydrates were affected by drought stress and phosphorus fertilizers. The use of phosphorus fertilizers and the severe drought stress increased their quantity.

The results suggest that conventional irrigation, application of phosphorus fertilizer and flat planting can increase biological yield compared to limited irrigation, non-application of phosphorus fertilizer and ridge planting.