Nutrient Uptake and Bacterial Structures Response to Varied pH Substrates in Grafted Melon Plant

Nutrient uptake is one of the most important processes for plant growth and soil microbes regulate the processes of nutrient cycling. We studied the influence of varied pH substrates on grafted melon (Cucumis melo L.) plants' growth and root bacterial communities. Six pH levels of substrates and two pumpkin rootstocks were selected to evaluate the impact of pH on the grafted melon plants' growth. Nutrient uptakes in nongrafted and grafted plant were measured, and Illumina MiSeq sequencing was performed to analyze the microbial community structures. pH considerably influenced the nutrient uptake of grafted melon plants. Using two rootstocks can significantly increase the nitrogen (N), phosphorus (P), and potassium (K) absorption in the scion or rootstock section of the grafted seedling plant regardless of pH levels in substrates, and many nutrients were absorbed at the pH range of 6.0 to 6.5. Few nutrients were taken up under low (5) or high pH (8). N, P, and K in grafted plant increased by 3.87-, 4.42- and 3.60-fold higher than those in nongrafted melon plant The phyla Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Gemmatimonadetes were the most predominant bacteria. The pH values and available N and P were considerably linked to bacterial community compositions. Our data demonstrated that pH played a vital role in the nutrient uptake of grafted melon plants and shifts bacterial structures in substrates when using pumpkin as rootstocks. Our study provides an example illustrating the importance of nutrient uptake of grafted seedlings in varied pH substrates. (C) 2020 Friends Science Publishers