Foliar application of uniconazole improves yield through enhancement of photosynthate partitioning and translocation to tuberous roots in sweetpotato

ABSTRACT

To examine the effects of uniconazole (UCZ) on the distribution and transport of photosynthate in sweetpotatoes, three spraying levels of UCZ, 0 (control), 50 and 100 mg L⁻¹, were exposed to an experimental field cultivated with Jishu26 (‘J26ʹ) and Xushu32 (‘X32ʹ) varieties. Compared to control, the distribution of carbon-13 (¹³C) was significantly higher in the tuberous roots of both varieties treated with UCZ. In addition, UCZ treatments promoted a desirable top-to-base sucrose gradient and significant greater declines in the top-to-bottom amino acid and potassium ion (K⁺) gradients along the stem. Higher tuberous root yields were found in the UCZ-treated ‘J26ʹ and ‘X32ʹ. In comparison to 50 mg L⁻¹ UCZ, ‘J26ʹ treated with 100 mg L⁻¹ UCZ exhibited significantly higher distribution ratio of ¹³C in tuberous root, and reductions in the top-to-bottom amino acid and K⁺ gradients along the stems at 105 and 150 days after planting. Furthermore, 100 mg L⁻¹ of UCZ application exhibited a significantly higher tuberous root yield. For ‘X32ʹ, the two concentrations of UCZ demonstrated no significant differences in these parameters. A reasonable distribution structure of photosynthates that responsible for high yields is associated with the desirable sucrose, ammonia nitrogen (N) or K⁺ gradient along the stems caused by UCZ application.

KEYWORDS:

• Uniconazole
• isotope ¹³C distribution
• photosynthate transport
• tuberous root yield
• sweetpotato

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 31501261]; the Natural Science Foundation of the Shandong Province [grant number ZR2015YL074]; the China’s Agriculture Research System for Sweetpotato [grant number CARS-10-B-08]; the Youth Scientific Research Fund from the Shandong Academy of Agricultural Sciences [grant number 2015YNQ16]; and the Modern Agricultural Technology System of Tubers and Root Crops in Shandong Province [grant number SDAIT-16-09].