ARBUSCULAR MYCORRHIZAL FUNGAL COLONIZATION OF CAPSICUM ROOTS AS MODULATED BY ORGANIC MULCHING: IMPLICATIONS FOR PHOSPHORUS ACQUISITION, WATER USE EFFICIENCY, AND PATHOGEN RESISTANCE
Arbuscular mycorrhizal fungi (AMF) constitute the most ecologically significant mutualistic symbiosis of Capsicum roots, mediating phosphorus (P) acquisition, water relations, and induced systemic resistance against soil-borne pathogens under conditions of nutritional and hydric stress. Organic mulching, through its documented effects on soil organic matter, moisture content, and rhizobiome composition, creates microenvironmental conditions that profoundly influence AMF colonization dynamics in the Capsicum rhizosphere. This study quantified AMF root colonization rates, phosphatase enzyme activity, plant P uptake efficiency, water use efficiency (WUE), and Fusarium wilt incidence in Capsicum annuum cv. Sombo under four organic mulch treatments (rice husk, composted poultry manure, green leaf manure, and wood chip mulch) applied at 10 t/ha in a randomized complete block design across two cropping seasons. AMF colonization rates were assessed at 45 and 90 DAT using the grid-line intersection method following Phillips and Hayman (1970) clearing and staining protocol. Results demonstrated AMF colonization rates of 62.4–84.7% under organic mulch treatments compared to 34.2% in the unmulched control, with composted poultry manure mulch achieving the highest colonization (84.7 ± 4.2%), leaf P concentration (3.84 mg P/g DW), WUE (14.8 kg fruit/mm water), and lowest Fusarium incidence (11.4%). These findings establish that organic mulching enhances AMF-mediated plant nutrition and defence in Capsicum through rhizobiome shifts that favour mycorrhizal helper bacteria and AMF propagule viability.
Keywords: arbuscular mycorrhizal fungi, Capsicum annuum, organic mulch, phosphorus uptake, water use efficiency, Fusarium wilt, rhizobiome
