Department of Forestry, University of Illinois, 61801, Urbana, Illinois.
J Chem Ecol. 1983 Aug;9(8):1175-83. doi: 10.1007/BF00982220.
Nitrogen-fixing nurse crops and cocrops of plant species nodulated byFrankia andRhizobium have been used to promote the growth of black walnut trees. Although walnut is known to inhibit the growth of certain associated plants due to its allelopathic derivative juglone (5-hydroxy-1,4-napthoquinone), juglone inhibition of symbiotic, nitrogen-fixing soil microorganisms had not been investigated. This research revealed that a concentration of 10(-3) M juglone absolutely inhibited the growth in vitro of aFrankia isolate from root nodules of red alder and ofRhizobium japonicum strain 71. Lesser concentrations of juglone inhibited the growth of these bacteria relative to the controls. The more-rapidly growingRhizobium strain exhibited slight growth at 10(-4) M juglone concentration, whereasFrankia growth was completely inhibited. Considering both the susceptibility of the host plant and nitrogen-fixing endophyte to the allelochemical juglone, caution should be exercised in selecting nitrogen-fixing plants as nurse crops for black walnut.
固氮根瘤菌和弗兰克氏菌共生的植物种的氮固定根瘤苗和伴生苗已被用于促进黑胡桃的生长。尽管众所周知，由于其化感衍生胡桃醌（5-羟基-1,4-萘醌），核桃会抑制某些相关植物的生长，但尚未研究胡桃醌对共生固氮土壤微生物的抑制作用。这项研究表明，浓度为 10(-3) M 的胡桃醌绝对抑制了来自红桤木根瘤的弗兰克氏菌分离株和 Rhizobium japonicum 菌株 71 的生长。与对照相比，较低浓度的胡桃醌抑制了这些细菌的生长。生长较快的 Rhizobium 菌株在 10(-4) M 胡桃醌浓度下表现出轻微的生长，而 Frankia 的生长则完全受到抑制。考虑到寄主植物和固氮内共生体对化感物质胡桃醌的敏感性，在选择固氮植物作为黑胡桃的根瘤苗时应谨慎。
