Inducible regulation of allelopathic potential in different wheat genetypes under drought and prohydrojasmon (PDJ) treatment

In a pot experiment, growth adaptation of four winter wheat (Triticum aestivum L.) accessions was investigated following seed pretreatment by soaking with prohydrojasmon (a kind of exogenous hormone at 10 mg·L^-1) before sowing. The seeds were subjected to artificial soil water regulation at 75% and 45% field capacity at the start of greening. Also in the experiment, the photosynthesis level, water use, variation of weed-controlling effect of allelopathy of wheat under acclimatized soil water and PDJ treatment was conducted. Soil drought and PDJ were used to stimulate the overall allelopathic inhibition and weed-resistance of wheat in the pot trial. The study shows that physiological response of “Lankao 95-25” and “Xiaoyan 6” to water shortage and PDJ is significant due to enhanced leaf net photosynthetic rate, water use efficiency and stoma capacity. Under PDJ, photosynthetic rate of “Yumai 66” obviously increases. However, water use efficiency decreases, while drought stress has just the opposite effect on “Yumai 66”. Under PDJ treatment, leaf net photosynthetic rate and water use efficiency of “Lankao 217” decrease. Based on Canonical Correspondence Analysis (CVA), water deficit and PDJ change the phenotype and photosynthetic physiology of plants, consequently influencing weed-controlling effect of allelopathy. On the average, allelopathic potential in intact wheat plants has a significant correlation with wheat weed-resistance expressed with weed biomass. Wheat weed-resistance characteristics are significantly directly related with wheat photosynthetic rate, transpiration rate and water use efficiency. However, they are significantly inversely related with aboveground biomass, plant height, node distance and stoma conductance.