Effect of arbuscular mycorrhizal fungi on early growth, root colonization, and chlorophyll content of North Maluku nutmeg cultivars

This study aimed to investigate the agronomic traits of nutmeg transplanting by arbuscular mycorrhizal fungi (AMF) inoculation. The low-fertility soil of Sofifi North Maluku was subjected to a slow early growth stage of nutmeg cultivars. A completely randomized design was used in the experiment. The first factor was three different AMF doses: 0, 4, and 8 g seedlings-1. The second factor consisted of three cultivars: "Ternate 1," "Tobelo 1," and "Makian." Root colonization and agronomic traits were measured 28 weeks after inoculation and transplantation. Results showed that AMF inoculation increased the AM colonization by 2.5-39.0%, significantly increased the leaf area (LA) (p < 0.01) in all cultivars, and interacted with cultivars to increase chlorophyll a (Chl a) (p < 0.05), chlorophyll b (Chl b) (p < 0.01), and total Chl (p < 0.01). Cultivars "Makian" showed the highest Chl (188.4%) at 8 g seedling-1 doses of AMF that were significantly (p < 0.01) different from the cultivar "Tobelo 1" at the same dose. The largest mycorrhizal response was found in the cultivar "Ternate 1" (biomass increase of 30-37.0%). The cultivar "Ternate 1" produced the largest LA (36.7-106.9%) and shoot dry weight (27.8-45.8%) that were significantly (p < 0.01) different from the other cultivars. The percentage of AM colonization was strongly determined (R-2 = 0.88) by Chl a, Chl b, and K content in leaves. This technology is a breakthrough to increase LA and plant biomass in the early growth stage of nutmeg cultivation.