HORTSCIENCE 40(2): 381-385. (2005)
Influence of Arbuscular Mycorrhizae Indigenous to Peru and a Flavonoid on Growth, Yield, and Leaf Elemental Concentration of 'Yungay' Potatoes
Fred T. Davies, Jr. and Constantino M. Calderon

ABSTRACT. The influence of arbuscular mycorrhizal fungi (AMF) [two Peruvian mixed isolates, a pure isolate of Glomus intraradices] and the flavonoid, formononetin, were tested on growth, yield, and leaf elemental concentration of the Peruvian potato (Solanum tuberosum L.) 'Yungay'. Plants started from tissue culture-produced prenuclear minitubers of 'Yungay' were subjected to seven treatments, which included noncolonized (non-AMF) plants fertilized with Long Ashton nutrient solution modified to supply P at 11 and 44 μg•mL-1. All AMF plants received low P (11 μg•mL-1) and were inoculated with either a sierra-maize mixed isolate, sierra-papa mixed isolate, pure isolate of G. intraradices, sierra-maize mixed isolate + formononetin, or a sierra-papa mixed isolate + formononetin. Plants were grown in 3-L containers under shade house conditions in Lima, Peru. Non-AMF plants at low P had the poorest growth, while high P plants had the greatest overall growth. All AMF plants had greater growth, including a higher root to shoot ratio, higher phosphorus use efficiency [(g tuber)/(g P/kg tissue)], and a lower leaf to tuber ratio (indicating greater leaf efficiency in producing tuber dry matter), compared to non-AMF plants at low P. The mycorrhizal inoculation effect (MIE) ranged from +44% to +57%, indicating that 'Yungay' was moderately to highly mycorrhizal dependent. Plants colonized with the sierra-papa isolate + formononetin had the same tuber development and leaf to tuber ratio, compared to high P, non-AMF plants. Formononetin increased extraradical hyphae formation. Mycorrhizal enhancement was in part due to greater P, Fe, and Mg uptake, a higher phosphorus-use efficiency and greater extraradical hyphae formation.

DISCUSSION

This study shows the benefit of mycorrhiza as biofertilizers on growth, tuber yield, nutrient uptake and PUE of 'Yungay' potatoes in low input, sustainable agriculture systems of the Peruvian highlands, it is important to use native mycorrhiza. While some limited studies have been done with nonnative mycorrhiza in Peru (Calderon, 1994; Moreno, 1988), this is the first successful report, to our knowledge, where native mycorrhiza were used as biofertilizers to enhance growth and yield of the important potato cultivar 'Yungay'. There were differences in plant growth, nutrient uptake and PUE among the AMF isolates. Formononetin also enhanced the growth effectiveness of the two Peruvian mixed isolates.

Mycorrhizal Fungi