Differences between nitrogen-tolerant and nitrogen-susceptible sweetpotato cultivars in photosynthate distribution and transport under different nitrogen conditions

Abstract

To characterize the differences in photosynthate distribution and transport between nitrogen(N)-tolerant and N-susceptible sweetpotato cultivars under different N conditions, three N levels, including 0 (N0), 120 (N120), and 240 kg ha−1 (N240), were used in field experiments with the Jishu26 (J26) and Xushu32 (X32) cultivars in 2015 and 2016. The results from both years revealed that high N application reduced the tuberous root yield, the tuber/vine rate of carbon-13 (13C), and top-to-base (three equal segments of stem divided from the fifth opened leaf of the shoot tip to the main stem, defined as the top, middle, and base parts, respectively) gradients such as sucrose, ammonia N and potassium along the stem. ‘J26’ showed a higher yield than ‘X32’ under N0 but lower yield than ‘X32’ under N120 and N240. It also exhibited a higher 13C distribution to tuberous roots compared with that of ‘X32’ under N0, and the opposite trend was observed under N120 and N240. Under N0, ‘J26’ showed a steep top-to-base amino acid gradient and a significantly lower top-to-base sucrose increase along the stem in the late growth stage. Under N120 and N240, ‘X32’ exhibited a greater top-to-base decrease in the ammonia N along the stem during the main growth stages, a steep top-to-base sucrose gradient along the stem in the early growth stage, and a lower top-to-base sucrose increase along the stem in the middle and late growth stages. The formation of a reasonable photosynthate distribution structure attributed to high yield was related to a desirable sucrose, ammonia N or K+ gradient downward along the stem. These results might help provide farmers with sweetpotato cultivars using less or no N fertilizer in soils of different fertility and enhance the knowledge of yield-related physiology.

Fate of nitrogen in agriculture and environment: agronomic, eco-physiological and molecular approaches to improve nitrogen use efficiency

“…Duan et al [117] discuss their findings about N application to long and short vines of sweet potato, the both long-vine and short-vine cultivars have the peak yield for nitrogen applied as 30 and 90 kg ha −1 respectively. The cultivars of same production potential have reduced their yields, and the root yield of long vine is significantly lower than that of short vine for nitrogen 120 kg ha −1 .…”

Evaluation of Yield-Based Low Nitrogen Tolerance Indices for Screening Maize (Zea mays L.) Inbred Lines

“…The low nitrogen tolerant index (LNTI) and tolerant index (TI) were proposed to evaluate the efficiency of N use in different crops [16,18,48]. Previous studies of screening LN tolerant individuals have also focused on several physiological traits or agronomic traits, including root yield, sucrose content, starch content, leaf area, and above ground biomass [49]. Other researchers proposed different evaluation systems given different priorities in the study.…”

Involvement of nitrogen in storage root growth and related gene expression in sweet potato (Ipomoea batatas)

“…China is a major producer of sweet potato, the production of sweet potato was 72,031,782 tonnes in China, producing approximately 64% of the world's supply (FAOSTAT, ). Optimized field N management is an important issue in sweet potato cultivation because N is a major factor for growth and productivity (Mukhongo et al ., ; Duan et al ., ). Nitrogen affects vegetative growth, storage root growth and development, as well as dry matter accumulation in sweet potato (Mukhongo et al ., ; Duan et al ., ).…”

“…Optimized field N management is an important issue in sweet potato cultivation because N is a major factor for growth and productivity (Mukhongo et al ., ; Duan et al ., ). Nitrogen affects vegetative growth, storage root growth and development, as well as dry matter accumulation in sweet potato (Mukhongo et al ., ; Duan et al ., ). It has been reported that a low N concentration might increase sweet potato storage root number at an early growth stage (Wilson, ).…”