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Corn is the main food crop in China, while its growth and development need large amount of potassium. Soil available potassium deficiency has become an important factor restricting corn yield at present. In this paper,15 maize inbred lines of different genetic background were as materials, field experiments were conducted in the soil of natural potassium deficiency. The changes of root morphology under low potassium were investigated, and the relationships between root morphology and dry matter, potassium accumulation and yield, to explore the mechanism of enduring the low potassium stress in root morphology, we expect to provide the basis for better use of potassium in corn in future.The results were summarized as follows:1. Under low potassium stress, due to genotype differences, there were different adaptations in root morphology. In Seedling stage total root length in different inbred lines were increasing; However, in the Bootinging period mainly showed a decreasing trend, only a few inbred lines tended to increase. Root surface area, root volume in seedling stage and Bootinging stage showed a decreasing trend, while the root becomes more slender. Comprehensive analysis of root traits for maize response to low potassium stress can be drawn, among the 15 maize inbred lines, ZD-2,91-2,099 and 90-21-3 have relatively strong tolerance to low potassium, and CQ-2, ZD-1, D937,8112 and 835 are more sensitive to low potassium stress.2. Under low potassium stress, dry matter accumulation of maize reduced to different extent.91-2,099, and 90-21-3 were less affected by the potassium stress, while D937,8112 and 835 more sensitive to low potassium stress.3. Low potassium stress led to maize roots, shoots and whole plant K accumulation decreased, under low potassium stress, the K accumulation in plants LD9801,90-21-3 and 099 was significantly higher than the other inbred lines, in contrast LD9-1, ZD-2, D937 and 8112 greatly influenced by low potassium stress.Under low potassium stress, potassium efficiency ratio, grain K use efficiency and harvest index showed an increasing trend. K use efficiency of grain in 099,90-21-3, D937, D1029-2B were high, while in ZD-2,835,91-2 were low.90-21-3, D1029-2B,099 had higher harvest index, while the Q319, ZD-2,835 were relatively low.4. Maize shoot morphogenesis were of varying degrees of change under low potassium stress, Mainly in plant height, leaf area relatively become shorter and the decrease in Bootinging shoots were relatively more serious than in seedlings. The photosynthetic rate, stomata conductance, the intercellular CO2 concentration and transpiration rate of different inbred lines were all tending to decline, but the photosynthesis characteristic of 90-21-3,099 less affected than D937 and 835 by low potassium stress.5. Grain yield per plant under low potassium showed different levels of production. 90-21-3, LD9801,099 declined a lesser extent, but D937,835, ZD-1 response to low potassium stress were more sensitive. The biomass and harvest index are co-determining economic yield, In low potassium,90-21-3, LD9801,099 are all have higher biomass and relatively high harvest index. CQ-2, D937,835, LD9-1 biomass and harvest indexes were lower. Under low potassium,100 grain weight and the number of grains per ear were decreased. Ear length shorter; Ear dimeter thinner; Ear tip growth. Comprehensive analysis, the conclusion has the inbred lines’ear traits of 21-3,90-LD9801, CQ-2 less affected by low potassium stress than the ZD-1,835.Through the comprehensive analysis on the relation between the changes of root morphology and dry matter accumulation, potassium efficiency and the yield can conclude, 90-21-3,099 with low potassium intimidation has relatively higher tolerance than D937,835 under low potassium stress.
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