Effects of potassium deficiency on photosynthesis and photoprotection mechanisms in soybean(Glycine max(L.)Merr.)

Potassium is an important nutrient element requiring high concentration for photosynthetic metabolism.The potassium deficiency in soil could inhibit soybean（Glycine max（L.） Merr.） photosynthesis and result in yield reduction.Research on the photosynthetic variations of the different tolerant soyben varieties should provide important information for high yield tolerant soybean breeding program.Two representative soybean varieties Tiefeng 40（tolerance to K^＋ deficiency） and GD8521（sensitive to K^＋ deficiency） were hydroponically grown to measure the photosynthesis,chlorophyll fluorescence parameters and Rubisco activity under different potassium conditions.With the K-deficiency stress time extending,the net photosynthetic rate（Pn）,transpiration rate（Tr） and stomatal conductance（Gs） of GD8521 were significantly decreased under K-deficiency condition,whereas the intercellular CO2 concentration（Ci） was significantly increased.As a contrast,the variations of Tiefeng 40 were almost little under K-deficiency condition,which indicated tolerance to K^＋ deficiency variety could maintain higher efficient photosynthesis.On the 25 th d after treatment,the minimal fluorescence（F0） of GD8521 was significantly increased and the maximal fluorescence（Fm）,the maximum quantum efficiency of PSII photochemistry（F√Fm）,actual photochemical efficiency of PSII（φ（PSII））,photochemical quenching（qp）,and electron transport rate of PSII（ETR）were significantly decreased under K^＋ deficiency condition.In addition,the Rubisco content of GD8521 was significantly decreased in leaves.It is particularly noteworthy that the chlorophyll fluorescence parameters and Rubisco content of Tiefeng 40 were unaffected under K^＋ deficiency condition.On the other hand,the non-photochemical quenching（qN） of Tiefeng 40 was significantly increased.The dry matter weight of Tiefeng 40 was little affected under K^＋ deficiency condition.Results indicated that Tiefeng 40 could avoid or relieve the destruction of PSII caused by exceeded absorbed solar energy under K-deficiency condition and maintain natural photosynthesis and plant growth.It was an essential physiological mechanism for low-K-tolerant soybean under K-deficiency stress.

Research on strategies for reducing the irritability of potassium cocoyl glycinate in cleansing

Background:Potassium cocoyl glycinate,a kind of amino acid surfactant,is widely used as major component for facial cleansing.However,the interaction between surfactants and compounds in the stratum corneum has been suggested as a contributing factor to their potential skin irritancy.Objective:This study aimed to the effects of adding surfactants,polymers,lipids and active substances on diminishing skin irritation caused by potassium cocoyl glycinate.Materials and methods:Zein test and Hemolysis test enabled the identification of irritation to proteins and cells in the studied binary systems.The critical micelle concentration(CMC)was evaluated by the surface tension method.The power of the analyzed polymers to diminish irritation of potassium cocoyl glycinate was represented by the reduction rate.Results:(1)Amphoteric surfactants and nonionic surfactants are effective at reducing the irritation of potassium cocoyl glycinate in some cases by reducing CMC;(2)Addition of polymers to the potassium cocoyl glycinate solutions improves its safety of use.Hydroxypropyl methylcellulose could reduce the irritation by 88.63%;(3)Combining most lipids can assist in declining the irritation,Lppg-28-Buteth-35 could inhibit the irritation of red blood cells by 16.52%;(4)The effects of active substances varied,hydrolyzed sodium hyaluronate results in a significant reduction in irritation to cells.Conclusion:In facial cleansers based on potassium cocoyl glycinate,supplying co-surfactant,polymers,lipids and active substances can reduce the irritation to some extent,however,the effects are various.