The Response Of Chinese Fir Families With Different Root Architectures To Nutrient Niche Competition Under Low Phosphorus Stress

Adjacent Plants could complement in soil resource utilization,due to the difference of root space structures.Some direct contact or nearby plants were able to avoid competition of the same genotype plants by root dislocation,so the root dislocation was of great significance to the growth of plants.At present,a great deal of researches on the plant root nutrition niche competition were given priority to the root competition between different plant species,but the competition between different varieties from the same plant root system was so less that failed to reveal different root architecture configuration and interspecies interaction mechanism of the same tree species with different genotypes.In view of this,the 27th family(the root architecture was like as "inverted umbrella")and 28th family(the root architecture was like as "umbrella")of Chinese fir were chosen as the research objects based on the early study of the tutor team.Through the sand culture designation of different phosphorus gradient,and building three adjacent plant competition patterns of "umbrella-umbrella","inverted umbrella-inverted umbrella" and "umbrella-inverted umbrella",the differences of root behavior looking for phosphorus between the different root architecture in Chinese fir families under low P stress were analyzed from the perspective of the nutrient foraging.The differences of Chinese fir's biomass allocation,root morphology and P utilization in different competition levels were compared.The response of morphology and architecture to the adjacent plant competition in Chinese fir families was researched This study will provide a scientific theoretical basis for different root architecture configuration and interspecies interaction mechanism in Chinese fir management.The main results were as follows(1)For the 27th family in the same root architecture adjacent plant competition:the two were all inclined to distribute more roots in the competitive area at both stage of early and late.The overlap of root distribution in different soil level of competitive area was larger under light and heavy P stress,lesser under normal P supply.For the 28th family in the same root architecture adjacent plant competition:with the passage of time,the root competition of the two was intense under light and heavy P stress,and the soil layer of the competition moved downward.(2)The 27th and 28th family formed adjacent plant competition:the 27th family was sensitive to the competitive environment and tended to distribute more root in the competitive area;while the root distribution of the 28th family between competitive and non-competitive area had no significant difference.Both 27th and 28th family seedlings tended to distribute more root in the competitive area;but to reduce the overlap of root distribution in different soil layer of the competitive area.And with the passage of time,both 27th and 28th family seedlings tended to distribute more root in the competitive area under light and heavy P stress;while the root distribution between competitive and non-competitive area had no significant difference;and tended to reduce the overlap of root distribution in different soil layer of the competitive area.So the growth of root could coordinate with each other in order to reduce the overlap of root distribution.(3)As the passage of time,the root of the total biomass,total root length,total surface area,average diameter and total volume of both 27th and 28th family seedlings increased on a whole under the light P stress and the different root architecture adjacent plant competition,and were characterized by competitive area significantly greater than the non-competitive area.And the root-shoot ratio increased;the proportion of underground root biomass increased.The P content of root at the late stage was less than the early;while the P content of leaf and stem had no obvious difference between the early and late stage.So as the P in the growth medium was consumed,in order to guarantee the growth of aboveground part,Chinese fir transferred more P aboveground.The environment promoted Chinese fir growth that the light P stress and the different root architecture adjacent plant competition.So in the plantation of Chinese fir plantation,27th and 28th family with different root architectures can be chosen to improve the yield.