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Abstract: Few systemic assessments have evaluated the success of these afforestation programs in alpine semiarid desert ecosystems in the Qinghai‐Tibet Plateau. In this study, we investigated the influences of three Salix cupularis plantation age classes (6, 18, and 34 years) on the carbon (C), nitrogen (N), and phosphorus (P) storages and stoichiometry of the soil–plant ecosystem. The consequences of S. cupularis plantation induced soil spatial heterogeneity. The soil–plant ecosystem C storage increased after the plantation. The N storage showed an increasing trend from 6 to 18 years and then slightly decreased. The P storage presented a continuously declining trend. The result indicated that the imbalance in soil N, P, C occurred with plantation age because of the imbalance of their inputs. The N and P uptakes from subsoil and redistribution to topsoil by S. cupularis may contribute to meet N and P demands for the understory plants. Leaf N:P ratios varied from 8.3 to 17.5. These results imply that N and P status are the main factors limiting plant growth in the alpine‐cold desert ecosystem. Thus, we recommend adding N and P fertilizers during plant growth. [ABSTRACT FROM AUTHOR]

High P-efficiency (IS-22-30,IS-22-25) and low P-efficiency (IS-07-07) wild barley cultivars were chosen to evaluate characteristics of phosphorus uptake and utilization, and properties of phosphorus fractions in rhizosphere and non-rhizosphere in a pot experiment with 0 (CK) and 30 mg P.kg-1 supplied as only Pi (KH2 PO4), only Po (phytate) or Pi+Po (KH2 PO4 + phytate). The results showed that dry matter and phosphorus accumulation of wild barley in the different treat- ments was ranked as Pi> Pi+Po> Po>CK. In addition, dry matter yield and phosphorus uptake of wild barley with high P-efficiency exhibited significantly greater than that with low P-efficiency. The concentration of soil available phosphorus was significantly different after application of different phosphorus sources, which was presented as Pi > Pi+Po> Po. The concentration of soil available phosphorus in high P-efficiency wild barley was significantly higher than that of low P-efficiency in the rhizosphere soil. There was a deficit in rhizosphere available phosphorus of high P-efficiency wild barley, especially in Pi and Pi+Po treatments. The inorganic phosphorus fractions increased with the increasing Pi treatment, and the concentrations of inorganic phosphorus fractions in soil were sorted as follows: Ca10-P > O-P > Fe-P > Al-P > Ca2-P > Ca8-P. The contents of Ca2-P and source treatment. In addition, enrichment of Al-P and Fe-P was observed in Pitreatment in rhizo- sphere soil. The concentrations of organic phosphorus fractions in soil were sorted as follows: moderate labile organic phosphorus > moderate resistant, resistant organic phosphorus > labile or- ganic phosphorus. The labile and moderate labile organic phosphorus enriched in rhizosphere soil and the greatest enrichment appeared in Pitreatment. Furthermore, the concentrations of moderate resistant organic phosphorus and resistant organic phosphorus decreased in rhizosphere soil. The concentrations of labile and moderate labile organic phosphorus in rhizosphere soil of high P-efficiency wild barley were significantly higher than that of low P-efficiency wild barley in each phosphorus source treatment. However, moderate resistant organic phosphorus and resistant organic phosphorus concentrations had no significant difference between the two genotypes. Wild barley with high P-efficiency demonstrated a greater ability of mobilization and uptake Ca2-P, Ca8-P, Al-P and labile organic phosphorus than that with low P-efficiency under Pideficiency. [ABSTRACT FROM AUTHOR]

A total of twenty seven middle maturing rice varieties as parent materials were divided into four types based on P use efficiency for grain yield in 2011 by field experiment with normal phosphorus (P) application. The rice variety with high yield and high P efficiency was identified by pot experiment with normal and low P applications, and the contribution rates of various P efficiencies to yield were investigated in 2012. There were significant genotype differences in yield and P efficiency of the test materials. GRLu17/AiTTP//Lu17_2 (QR20) was identified as a variety with high yield and high P efficiency, and its yields at the low and normal rates of P application were 1.96 and 1.92 times of that of Yuxiang B, respectively. The contribution rate of P accumulation to yield was greater than that of P grain production efficiency and P harvest index across field and pot experiments. The contribution rates of P accumulation and P grain production efficiency to yield were not significantly different under the normal P condition, whereas obvious differences were observed under the low P condition (66.5% and 26.6%). The minimal contribution to yield was P harvest index (11.8%). Under the normal P condition, the contribution rates of P accumulation to yield and P harvest index were the highest at the jointingheading stage, which were 93.4% and 85.7%, respectively. In addition, the contribution rate of P accumulation to grain production efficiency was 41.8%. Under the low P condition, the maximal contribution rates of P accumulation to yield and grain production efficiency were observed at the tilleringjointing stage, which were 56.9% and 20.1% respectively. Furthermore, the contribution rate of P accumulation to P harvest index was 16.0%. The yield, P accumulation, and P harvest index of QR20 significantly increased under the normal P condition by 20.6%, 18.1% and 18.2% respectively compared with that in the low P condition. The rank of the contribution rates of P efficiencies to the yield was in order of P uptake efficiency > P utilization efficiency > P transportation efficiency. The greatest contribution rate of P accumulation to the yield was noticed at the jointingheading stage with the normal P application while it reached the maximal value at the tilleringjointing stage with the low P application. Therefore, these two stages may be the critical periods to coordinate high yield and high P efficiency in rice. [ABSTRACT FROM AUTHOR]

A pot experiment was carried out to test the effects of phosphorus (P) supply levels (25, 50, and 75 mg P2O5 . kg-1) with two P genotype (efficient DH110+ and DH147, inefficient DH49) barleys on root morphology and the relationships between root morphology and P uptake. The results showed that barley biomass and P uptake were significantly reduced by low P stress. Efficient genotype barley biomass and P uptake were 1.24-1.70 and 1.18-1.83 times as much as those of inefficient genotype barley respectively. The total root length, total root surface area, average root diameter, adventitious root length and root surface area, lateral root length and root surface area of P efficient genotype barley were significantly reduced with decreasing the P supply level in soil. The total root length, total root surface area, specific root length, lateral root length and surface area of P efficient genotype barley were 1.46-2.06, 1.12-1.51, 1.35-1.72, 1.69-2.42; and 1.40-1.78 times as much as that of those of P inefficient genotype barley, respectively, while the average root diameter was 70.6% - 90.2% of P inefficient genotype barley. Principal component analysis showed that the average root diameter, specific root surface area and specific root length could be used to distinguish two P genotype barleys. Partial least squares regression analysis showed that the total root length, total root surface area made great contributions to P uptake of barley in soil. The contribution of the adventitious root length and surface area on P uptake of barley decreased significantly and the average root diameter, specific root length, lateral root length and root surface area increased with the decreasing P supply level in soil. P efficient genotype barley adapted to low P stress through maintaining the lateral root growth, increasing the specific root length and root fineness.

High P-efficiency (IS-22-30, IS-22-25) and low P-efficiency (IS-07-07) wild barley cultivars were chosen to evaluate characteristics of phosphorus uptake and utilization, and properties of phosphorus fractions in rhizosphere and non-rhizosphere in a pot experiment with 0 (CK) and 30 mg P · kg(-1) supplied as only Pi (KH2PO4), only Po (phytate) or Pi + Po (KH2PO4+ phytate). The results showed that dry matter and phosphorus accumulation of wild barley in the different treatments was ranked as Pi > Pi + Po > Po > CK. In addition, dry matter yield and phosphorus uptake of wild barley with high P-efficiency exhibited significantly greater than that with low P-efficiency. The concentration of soil available phosphorus was significantly different after application of different phosphorus sources, which was presented as Pi > Pi + Po > Po. The concentration of soil available phosphorus in high P-efficiency wild barley was significantly higher than that of low P-efficiency in the rhizosphere soil. There was a deficit in rhizosphere available phosphorus of high P-efficiency wild barley, especially in Pi and Pi+Po treatments. The inorganic phosphorus fractions increased with the increasing Pi treatment, and the concentrations of inorganic phosphorus fractions in soil were sorted as follows: Ca10-P > O-P > Fe-P > Al-P > Ca2-P > Ca8-P. The contents of Ca2-P and Ca8-P for high P-efficiency wild barley showed deficits in rhizosphere soil under each phosphorus source treatment. In addition, enrichment of Al-P and Fe-P was observed in Pi treatment in rhizosphere soil. The concentrations of organic phosphorus fractions in soil were sorted as follows: moderate labile organic phosphorus > moderate resistant, resistant organic phosphorus > labile organic phosphorus. The labile and moderate labile organic phosphorus enriched in rhizosphere soil and the greatest enrichment appeared in Pi treatment. Furthermore, the concentrations of moderate resistant organic phosphorus and resistant organic phosphorus decreased in rhizosphere soil. The concentrations of labile and moderate labile organic phosphorus in rhizosphere soil of high P-efficiency wild barley were significantly higher than that of low P-efficiency wild barley in each phosphorus source treatment. However, moderate resistant organic phosphorus and resistant organic phosphorus concentrations had no significant difference between the two genotypes. Wild barley with high P-efficiency demonstrated a greater ability of mobilization and uptake Ca2-P, Ca8-P, Al-P and labile organic phosphorus than that with low P-efficiency under Pi deficiency.

A total of twenty seven middle maturing rice varieties as parent materials were divided into four types based on P use efficiency for grain yield in 2011 by field experiment with normal phosphorus (P) application. The rice variety with high yield and high P efficiency was identified by pot experiment with normal and low P applications, and the contribution rates of various P efficiencies to yield were investigated in 2012. There were significant genotype differences in yield and P efficiency of the test materials. GRLu17/AiTTP//Lu17_2 (QR20) was identified as a variety with high yield and high P efficiency, and its yields at the low and normal rates of P application were 1.96 and 1.92 times of that of Yuxiang B, respectively. The contribution rate of P accumulation to yield was greater than that of P grain production efficiency and P harvest index across field and pot experiments. The contribution rates of P accumulation and P grain production efficiency to yield were not significantly different under the normal P condition, whereas obvious differences were observed under the low P condition (66.5% and 26.6%). The minimal contribution to yield was P harvest index (11.8%). Under the normal P condition, the contribution rates of P accumulation to yield and P harvest index were the highest at the jointing-heading stage, which were 93.4% and 85.7%, respectively. In addition, the contribution rate of P accumulation to grain production efficiency was 41.8%. Under the low P condition, the maximal contribution rates of P accumulation to yield and grain production efficiency were observed at the tillering-jointing stage, which were 56.9% and 20.1% respectively. Furthermore, the contribution rate of P accumulation to P harvest index was 16.0%. The yield, P accumulation, and P harvest index of QR20 significantly increased under the normal P condition by 20.6%, 18.1% and 18.2% respectively compared with that in the low P condition. The rank of the contribution rates of P efficiencies to the yield was in order of P uptake efficiency > P utilization efficiency > P transportation efficiency. The greatest contribution rate of P accumulation to the yield was noticed at the jointing-heading stage with the normal P application while it reached the maximal value at the tillering-jointing stage with the low P application. Therefore, these two stages may be the critical periods to coordinate high yield and high P efficiency in rice.