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Potassium translocation combined with specific root uptake is responsible for the high potassium efficiency in vegetable soybean

Author:
Liu, Changkai, Tu, Bingjie, Wang, Xue, Jin, Jian, Li, Yansheng, Zhang, Qiuying, Liu, Xiaobing, Ma, Baoluo
Source:
Crop & pasture science 2019 v.70 no.6 pp. 516-525
ISSN:
1836-5795
Subject:
Glycine max, crops, genotype, hydroponics, leaves, potassium, potassium sulfate, root systems, soybeans, surface area, tissues, vegetables
Abstract:
Uptake of potassium (K) in crops depends mainly on the root system. Field, pot and hydroponic experiments were carried out to characterise root morphological traits and examine their roles in K uptake and utilisation of vegetable soybean (edamame) (Glycine max (L.) Merr.). Of 40 genotypes, two high K-efficiency (HKE) and two low K-efficiency (LKE) genotypes were identified and compared at two levels of K application: nil or 120 kg K₂SO₄ ha–¹. HKE genotypes had shorter total root length and smaller root surface area and root volume than LKE genotypes, but responded earlier to low-K conditions by adjusting root architecture. In plants receiving nil K, total root length was increased by 10.4–21.8% for HKE genotypes but decreased by 5.5–9.5% for LKE genotypes at the V4 stage relative to plants receiving applied K. HKE genotypes were more efficient in redistributing K from source to sink tissue, especially from leaf. Of the total K in vegetative tissues, 35.0–46.4% was redistributed to seed in HKE genotypes, whereas only 19.7–28.2% was redistributed in LKE genotypes. HKE genotypes also had a higher specific K uptake rate (K uptake per unit root length), 1.6–1.7 times higher than LKE genotypes at the R5 stage. This indirectly indicated a stronger root K acquisition in HKE genotypes. This study suggests that future vegetable soybean improvement with greater K efficiency should be focused on the selection of higher K-redistribution rate and specific K-uptake rate.
Agid:
6481566