Effect of remained stem height on yield, quality of Inula helenium I. and on soil water content

To explore the reason causing low yield, poor quality of Inula helenium I., this paper investigated the influence of different remained stem heights on the yield, quality and water consumption of Inula helenium I. in Gannan plateau area using field single factor randomized block method. Research results showed that Inula helenium I. which was cut before blooming period in the last ten-day of July with remained stem height of 25 cm had the lowest water consumption, the best underground root traits (including main root length, root diameter, and root dry weight per plant), and the highest yield which was higher that control group by 18.73% (P < .01) Moreover, Inula helenium I. with remained stem height of 25 cm had the lowest ash content while the highest alantolactone content, therefore its quality was the best. The water use efficiency (WUE) of Inula helenium I. with remained stem height of 35 cm at September was the highest (1.12 kg⋅h⋅m^-2⋅mm^-1). However, in terms of biological yield WUE and economic yield WUE, Inula helenium I. with remained stem height of 15 cm was the highest. Therefore, it can be concluded that remained stem height from 15 to 25 cm is an ideal solution, which can not only save water, but also improve yield and quality of Inula helenium I.