Studies On Differences Of Potassium Nutrition And Its Physiological Mechanism Among Cotton Varieties

This study is focused on evaluating comprehensively the ability of adapting to low potassium conditions of the six cotton varieties that is using the method of combining hydroponic with pot experiment, which was in terms of cotton root morphology, root activity, potassium uptake kinetics, agronomic traits, plant NPK content, yield and quality, etc. The main results were as follows:1. This study is aim at comparing six varieties in response to low potassium stress through the hydroponic trial. The results showed that: Liao cotton 18, CCRI 35 and CCRI 64, they have a certain degree of superiority than another three cotton varieties both root morphology, root activity and K+ uptake kinetics parameters. Liao Cotton 18 has developed root. CCRI 35 has slender roots, this form is beneficial to its roots to absorb actively water and nutrients in growing medium. CCRI 64 has long thick roots, this form has radiation extensive range of configurations that can increase the effective surface area for the roots absorbing nutrients, resulting in more nutrients to promote robust growth of cotton. By analyzing root activity, we can see that when the cotton plants is grown in low potassium nutrient solution, the roots of these three varieties have a certain degree of enhancement in terms of optimum potassium in order to improve their own ability to adapt the environment’s stress.The root activity of other three varieties that are new cotton 99 B, Zhong zhi cotton 2nd and cotton CCRI 50 were reduced, and the CCRI 50 is the largest decline, which indicates CCRI 50 has more sensitive on potassium nutrition status.2. We used pot experiment to design of low, medium, and high potassium content gradient for studying six cotton varieties’ ability to adapt to different potassium levels and its yield and quality. The results show that: Liao Cotton 18, its aboveground dry weight, root dry weight, root length, plant height, leaf area and shoot ratio have more advantage than other varieties at the seedling and budding stage, CCRI 35 is second, and the new cotton 99 B is significantly lower than Liao cotton 18 and CRRI 35. CCRI 64 and CRRI 50, its aboveground dry weight, root dry weight, leaf area, boll number and seed cotton yield was significantly lower than that of other varieties in the seedling, budding, blooming period and boll opening stage, particularly its height.CCRI 35 its net photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO2 concentrations were higher than other varieties, which indicates cotton varieties have different photosynthesis. CRRI 35 has strongest photosynthesis, and CCRI 64 and CCRI 50’s photosynthetic capacity is relatively weak.Under low potassium level, the root activity of CCRI 35 is maximum and CCRI 64 is minimum. The root activity of CCRI 35 and Zhong zhi cotton 2nd was significantly higher than the other four varieties under middle potassium level; the root activity of Liao cotton 18 is strongest, CCRI 50 is weakest under high potassium level. The root activity of CCRI 35 is stronger than that of middle potassium and high potassium, which indicates it has strong adaptable ability to stress; With increasing potassium levels, the root activity of Zhong zhi cotton 2nd and CCRI 64 also enhanced; With increasing potassium levels, the root activity of CCRI 50 was first increased and then decreased; root activity of Liao cotton 18 and new 99 B was first decreased and then increased, they both enhance root stress of living in order to better adapt to the low potassium stress adversity through itself certain regulatory mechanisms.The different parts of NPK content and accumulation of the 6 cotton varieties were shown a certain degree of difference.The absorption of NPK of Liao cotton 18, CCRI 35, Zhong zhi 2nd and the new cotton 99 B are higher than that of CCRI 64 and CCRI 50.Under low potassium levels, the seed cotton yield and lint yield of new cotton 99 B are higher than other varieties; and CCRI 35 and Liao cotton 18 show yield advantage under middle potassium and high potassium levels. This also shows that the cotton varieties’ yield displays a certain degree of difference in the different potassium levels.