Cassava ( Manihot esculenta Crantz) is a heat- and moisture-loving plant, with plastic film coverage and planting intensity considered important practices for regulating soil temperature and moisture. However, the physiological and biochemical responses and their rhizosphere microbial bases induced by these two practices remain unclear. In the present work, a 1-year field trial was carried out in a tropical region in China to investigate the effects of plastic mulch silver-up cover with single row (CK), black-side-up cover with single row (T1), silver-side-up cover with double row (T2), and silver-side-up cover with inter-cropping (T3) on the growth and rhizosphere microbial ecology of the cassava variety Nanzhi 199. Compared with CK and T1, T2 and T3 significantly improved the growth parameters and tuber yield of Nanzhi 199 by 9.1%–10.0% (plant weight) and 15.1%-26.0% (tuber yield), respectively, largely attributed to reducing temperature (0.7–3.0 °C), increasing moisture (15.4%–26.8%), and enhancing soil nutrient availability (T3 elevating A-K uptake, activating phosphorus via ACP, optimizing NH₄⁺-N supply). Metagenomic analysis showed that T3 most significantly affected rhizosphere microbial diversity, metabolic potential, and root exudate profiles, strongly linked to nutrient cycling- and growth-promoting Chloroflexota, Actinomycetota, and Pseudomonadota. T2 and T3 elevated soil differential metabolites number by 1.1–2.1-fold and altered root exudate profiles, attributed to the upregulation of organic oxygenated compounds and organic acids in soil metabolites, and lipids and lipid-derived molecules in root exudates. Shifts in plant growth, root exudate profiles, and their properties were associated with the rhizosphere microbial community driven by the interactions of film coverage and planting patterns. These findings improved our understanding of the micro-ecological mechanisms that play a role in plastic film coverage and planting patterns in enhancing cassava yield in tropical regions.
Hu et al. (Fri,) studied this question.