[Effect of Long-Term Biochar Application on Soil Respiration in Flue-Cured Tobacco Planting Fields in Henan Province].

A five year (2013-2017) experiment was conducted to explore the effects of biochar application on the dynamic changes in soil respiration, soil water, and heat factors under four treatments:CK (without biochar), T1 (with 1.5 t·hm-2biochar), T2 (with 15 t·hm-2biochar), and T3 (with 45 t·hm-2biochar). The results showed that:① the soil respiration rate in the growing season of flue-cured tobacco was significantly reduced by 25.89% under the five year application of medium-dose biochar (T2:15 t·hm-2) in soil, while it was significantly increased by 21.48% when the applied dose increased to 45 t·hm-2(T3) (P<0.05). ② The long-term application of medium-dose biochar in the soil significantly reduced the soil heterotrophic respiration and autotrophic respiration rates by 29.80% and 28.75%, respectively. Meanwhile, the application of high-dose biochar (T3:45 t·hm-2) significantly increased the heterotrophic respiration rate by 28.88%. In addition, the application of low-dose biochar (T1:1.5 t·hm-2) and medium-dose biochar significantly increased the proportion of autotrophic respiration, whereas the high-dose biochar application significantly increased the proportion of heterotrophic respiration (P<0.05). ③ The addition of low-dose biochar to the soil significantly reduced the soil temperature at 5 cm in the growing season of flue-cured tobacco, while the high-dose application significantly reduced the soil humidity. There was a significant index correlation between soil respiration and soil temperature at 5 cm but no significant correlation with soil humidity at 5 cm (P<0.05). Ultimately, the application of low-dose biochar for five years in soil had no effect on soil respiration, and the application of the proper amount of biochar had a carbon sequestration effect. Additionally, large-dose biochar application may be counterproductive. It is recommended that the application range of biochar should be controlled within 15 t·hm-2.

[Effect of Biochar Amendment on Physicochemical Properties and Fungal Community Structures of Cinnamon Soil].

To identify the effect of biochar addition on soil abiotic and biotic properties and provide evidence for the soil improvement with biochar input, the soil physiochemical properties and fungal community were investigated in a cinnamon soil after 3-year biochar additions of 10, 20, and 40 t ·hm-2. The relationship between the fungal community and edaphic physicochemical characteristics was also analyzed. The results showed that soil pH, moisture, total nitrogen (TN), and total organic carbon (TOC) significantly increased but dissolved organic carbon (DOC) content and soil bulk density decreased with biochar addition. High-throughput sequencing results indicated that biochar amendment had little influence on fungal α diversity but significantly changed the fungal community structure. The taxonomic classification showed that the dominant fungal phyla were Ascomycota, Zygomycota, and Basidiomycota, and these phyla accounted for more than 90% of the total sequences. The relative abundance of Ascomycota and Basidiomycota increased, while the abundance of Zygomycota decreased with biochar addition. At the genus level, biochar addition increased the relative abundances of Alternaria, Conocybe, and Aspergillus but decreased the relative abundances of Actinomucor and Gibberella. Redundancy analysis (RDA) showed that soil DOC, pH, and moisture were key environmental factors leading to the shift in the soil fungal community composition. In summary, the application of biochar changed the soil physicochemical properties, which drove the ecological succession of soil fungal communities.

[Effects of phosphorus fertilizer on the root system and its relationship with the aboveground part of flue-cured tobacco].

Using 'Yuyan 10' as the material, the effects of different phosphorus fertilizer application on root characteristics of tobacco, such as root dry mass and the difference of dry matter distribution and mineral nutrient accumulation between its above and underground parts were investigated. The results showed that the growth of flue-cured tobacco root system and the distribution of dry matter to the aboveground part were significantly promoted by phosphorus fertilizer application. The application of 30 kg P2O5 · hm(-2) led to the maximums of root dry mass, root volume, root activity and the minimum of root to shoot ratio. The maximum nutrient accumulation rates of root and leaf appeared 57-66 days after transplanting and 44-55 days after transplanting, respectively. Phosphorus could not only promote the mineral nutrition absorption of tobacco and the earlier appearance of maximum nutrient accumulation, but significantly promote the nutrient accumulation of the aboveground part. But, the positive effects described above would be weakened when the amount of phosphorus fertilizer was more than 30 kg P2O5 · hm(-2). Therefore, it's necessary to control the amount of phosphorus application to improve the quality of tobacco leaves.

[Effects of farmland shelterbelt on photosynthetic characteristics and grain yield of maize in Hexi corridor oasis].

Farmland shelterbelt is a main component of oasis agro-ecosystem in the Hexi corridor of Gansu Province, which plays an important role in maintaining local agricultural production and ecological balance. This paper studied the photosynthetic characteristics of maize at its grain-filling stage and the grain yield of maize under the protection of the shelterbelt. The results showed that at the same distances east and west of the shelterbelt, maize plants at the east side always intercepted more photosynthetic active radiation (PAR) than those at the west side. Within 20 m from the west side of the shelterbelt, the net photosynthetic rate (P(n)) of maize plants was lower because of the serious shading by trees; and within 15 m from the west side, the P(n) was lower than that from the east side. The grain yield of maize was decreased within 10 m from the east and 15-20 m from the west side, but increased or not affected in other locations.

[Analysis of RAPD on medicinal plants of Codonopsis pilosula].

OBJECTIVE: To study genetic diversity and genetic relationship among 9 cultivated and 4 nature populations of Codonopsis pilosula and C. pilosula var. modesta form Gansu Province at DNA level. METHODS: DNA of 217 individuals was amplified by 14 decamer primers from 200 radom primers. The polymorphic bands of RAPD were counted. And the results were analyzed by clustering analysis NTSYS-PC software. RESULTS: A total of 125 loci were detected by 14 arbitrary primers, among which 109 and 106 loci were polymorphic in C. pilosula and C. pilosula var. modesta respectively, and the percentage of polymorphic bands (PPB) were 87.20% and 84. 80%. The cluster analysis showed that 13 populations were divided into 2 groups. The one included 8 cultivated populations of C. pilosula, the other group consisted of a cultivated population and 4 nature populations of C. pilosula var. modesta. CONCLUSION: The RAPD results indicated that there was abundant genetic diversity in cultivated populations of C. pilosula and C. pilosula var. modesta. The genetic differentiation among 8 cultivated populations of C. pilosula was very small and related to their geographical distance. Only the cultivation in Wen County originated from C. pilosula var. modesta, while the other populations cultivated in Gansu Province belongs to C. pilosula.