Influence of high-carbon basal fertiliser on the structure and composition of a soil microbial community under tobacco cultivation.

Soil microorganisms play a crucial role in cycling soil nutrients and providing organic nutrients for plant growth and development. Fertilisation balances soil fertility and quality, and affects soil microbial communities. Fertilisation is a frontier subject in agricultural and environmental sciences. Here we showed that the application of high-carbon basal fertiliser treatment could improve the tobacco yield and quality when compared to chemical fertiliser, high-carbon basal fertiliser and mixed high-carbon chemical fertiliser. The potential reason is that different fertiliser treatments influence soil fertility, such as nitrogen, phosphorus, and other contents, besides soil organic matter. Further experiments revealed that populations of bacteria, fungi and actinomycetes fluctuated during tobacco development under different fertilisation treatments. Then we performed high-throughput sequencing of the 16S rRNA gene, and the results showed that the fertilisation treatments had significant effects on the microbial community, particularly within the finer taxonomic divisions or non-dominant taxa. Moreover, proteobacteria and fungal genera had significantly different relative abundances during tobacco growth under various tobacco developmental stages and fertilisation treatments. These results indicated that mixed high-carbon chemical fertiliser could improve soil fertility by influencing the soil microorganism, and that the fertilisation treatments impacted on the structure and composition of the microbial community, and especially the diversity of non-dominant taxa. However, more studies are needed to confirm their reliability.

[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.