This study focuses on two genotypes of cotton and explores different factors that were
able to affect the release of different forms of potassium (K) in the rhizosphere by
considering a biogeochemical process integrating plants, soils, and microorganisms.
The study indicated that both genotypes of cotton could effectively absorb exchange-
able potassium (eK) under limited potassium (LK) supply, and cotton plants could use 15
LK to sustain offspring, preferably under K-deficiency conditions. It was mainly due to
its significantly greater active absorbing surface area of root and comparatively
greater K+ maximum uptake rate (Imax), which caused more K accumulation in the
high-efficiency genotype cotton (HEG). Although Imax of the low-efficiency genotype
cotton’s (LEG’s) was greater, K accumulation in LEG was less, which might be 20
attributed to its significantly lower HEG and feedback inhibition on K taken up by
greater K concentration in the plant. The lint yield had a significant positive correlation
with boll number per plant, single boll weight, plant height, and number of fruit
branches, which indicated that increasing these agronomic parameters is the base for
increasing lint yield. There was a synergic action among humus, microorganisms, and 25
K in the rhizosphere soil. The cation exchange capacity (CEC) of reduced soils was less
under oxidized condition, due to collapse of the interlayer in response to increased
layer charge upon structural Fe reduction. Crop yields can be increased when fertilizer
K is applied according to proper ratio among different forms of potassium and humic
acid in soils. The middle-high plant height, lower initial fruit branch, more fruit 30
branches, more bolls, and larger boll size should receive more attention during highyielding
cotton breeding.