Study On Difference Of Physiological Characteristics In Soil Phosphorus Utilization Between High And Low Phosphorus Accumulating Cultivars Of Wheat Seedlings

Phosphorus (P) is an essential macronutrient for the normal growth anddevelopment of higher plant. However, most of P naturally occurs as indissolvableinorganic P and organic P in soils, both of which can be directly absorbed by rootsystem only after being transformed into dissoluble P However, the difference inphysiological characteristics is not completely understood yet. In this study, high(Baimaiwangzi, Yumai58, Yunong416, Jimai22) and low (Zhongyu5, Zhengmai9023, Zhengmai004and Shimai12) cultivars of wheat seedlings in total Paccumulation were chosen by screening45wheat varieties under field conditions andwere used to explored the difference in physiological characteristics of soil Putilization by hydroponic experiment. The results were as follows:1. When the wheat seedlings were cultured in the nutrition solutions supplied withcalcium phosphate, the total P accumulation in the seedlings of Zhengmai004andShimai12were significantly higher than the other six varieties, Baimaiwangzi, Yumai58and Jimai22were significantly higher than Yunong416, Zhongyu5and Zhengmai9023. When cultured in the nutrition solutions supplied with calcium dihydrogenphosphate, total P accumulation in the seedlings of Shimai12and Zhengmai004weresignificantly higher than the other six varieties.2. When cultured in the presence of phytic acid solution, the total P accumulationin the seedlings of Yumai58and Jimai22were significantly higher than the other sixvarieties, Yunong416, Zhongyu5, Shimai12and Zhengmai004were significantlyhigher than Baimaiwangzi and Zhengmai9023.3. The H+secretion of Shimai12and Zhengmai004were significantly higher thanthe other six varieties. Yumai58was significantly higher than Baimaiwangzi, Yunong416, Zhengmai9023, Zhongyu5and Jimai22.4. The acid phosphatase activity of Yumai58was significantly higher than the other seven varieties. Jimai22was significantly higher than Baimaiwangzi, Yunong416, Zhongyu5, Zhengmai9023, Zhengmai004and Shimai12.5. The results of absorption experiment showed that the Pi absorption rates ofZhongyu5and Jimai22were significantly higher than Baimaiwangzi, Yunong416,Yumai58, Zhengmai9023, Zhengmai004and Shimai12.6. Analysis of scanning images of root system of wheat seedling revealed that theroot length and root tip number of Zhengmai004and Shimai12were significantlyhigher than the other six varieties, the root surface area and root volume of Shimai12was significantly higher than the other seven varieties under the conditions of Pdeficiency. The root length and root number of Zhengmai004was significantly higherthan the other seven varieties, the root tip number of Yumai58and Zhengmai004were significantly higher than the other six varieties. The crossing of Jimai22wassignificantly higher than the other seven varieties under the condition of p normal.In conclusion, the main reasons which caused the difference of total Paccumulation in individual wheat seedling included the following aspects:(1) Strongercapacity in secreting H+and phosphatase, and more developed root systems, andhigher Pi absorption rates;(2) Stronger capacity in secreting proton and phosphatase,with higher uptake rates of Pi;(3) Stronger capacity in secreting H+and phosphatase,and developed root system;(4) Stronger capacity in secreting H+, more developed rootsystem, and higher Pi absorption rates;(5) Stronger capacity in secreting phosphataseand developed root system;(6) Stronger capacity in secreting H+and more developedroot system;(7) Stronger capacity in secreting phosphatase and higher Pi absorptionrates;(8) Stronger capacity in secreting H+, higher Pi absorption rates;(9) Higher Piabsorption rates;(10) Developed root system.Among the factors which caused the difference in soil P utilization by wheatseedling such as proton secretion, phosphatase activity, Pi absorption rate, morphologyof root system, any three, two and even one of these could result in the difference in Paccumulation in wheat seedlings. However, eight of ten factors were involved inproton secretion and phosphatase activity. Obviously, these were the most importantfactors which resulted in the difference in soil P utilization by wheat seedlings.Therefore, improved capacity of solublizing soil P by genetic manipulation of protonsecretion and phosphatase could increase P utilization efficiency in soils incombination with specific nutritional characters of wheat varieties.