Effect of Potassium Application on Root Growth and Yield of Sweet Potato and Its Physiological Mechanism

WANG Shun-Yi1 LI Huan1 LIU Qing1 SHI Yan-Xi1

(1.College of Resources and Environmental Science, Qingdao Agricultural University, Qingdao, China 266109)

【Abstract】The objective of this study was to investigate the physiological mechanism of potassium application on root growth and yield improvement in sweet potato. Two year field experiment was conducted with three potassium levels (0 kg hm−2, 75 kg hm−2, 150 kg hm−2, and 225 kg hm−2) to study the effects of potassium on root growth, 13C distribution, metabolic enzyme activity, photosynthetic characteristics and yield of sweet potato. Compared with CK, potassium treatments increased ETR by 12.7%–63.6%, and Pn by 7.2%–26.4%. Potassium application improved photosynthetic characteristics and accelerated the accumulation of photosynthate, providing material basis for root growth. However, potassium application was beneficial to the photosynthate products from shoots to roots, and root 13C distribution amount increased by 10.6%–66.2% (P < 0.05). Then, potassium application increased sucrose synthase, sucrose phosphate synthase and adenosine diphosphate glucose pyrophosphorylase activities and accelerated the assimilation of carbon in roots, thus improving the photosynthate accumulation in roots and promoting root differentiation and growth in sweet potato. In early growing stage, potassium application increased total root length by 13.6% –22.8% and the average diameter of root by 11.3%–51.9%, and significantly increased the differentiation from adventitious roots to fibrous roots and tuberous roots (P < 0.05), which was beneficial to the early formation of effective tuberous root, ensuring the effective number of tuberous roots per plant. Potassium treatments increased the root biomass and average tuberous root weight. Compared with CK, the potassium treatments increased yields by 5.8%, 24.3%, and 44.7% in 2014, and by 7.9%, 13.4%, and 22.8% in 2015, respectively.

【Keywords】 Sweet potato; Root growth; Photosynthetic characteristics; 13C distribution; C enzyme activities;

【Funds】 China Agriculture Research System (CARS-11-B-14) supported by the National Modern Agro-industry Technology System (CARS-11-B-14) Young Scientists Fund of the National Natural Science Foundation of China (31301854) the Natural Science Foundation for Young Scientists of China (31301854)

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(Translated by PAN Yu)

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This Article

ISSN:0496-3490

CN: 11-1809/S

Vol 43, No. 07, Pages 1057-1066

July 2017

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Abstract

  • 1 Materials and methods
  • 2 Results and analysis
  • 3 Discussion
  • 4 Conclusions
  • References