Open AccessThe rôle of the young lucerne plant in determining the infection of the root by the nodule-forming bacteria
Author(s) -
Henry Thornton
Publication year - 1929
Publication title -
proceedings of the royal society of london. series b, containing papers of a biological character
Language(s) - English
Resource type - Journals
eISSN - 2053-9185
pISSN - 0950-1193
DOI - 10.1098/rspb.1929.0019
Subject(s) - sowing , nodule (geology) , inoculation , biology , horticulture , root nodule , agronomy , bacteria , nitrogen fixation , paleontology , genetics
Observations have been made at Rothamsted over a period of about five years upon the development of nodules on young seedlings of lucerne (Medicago sativa, L.). Some thousands of seedlings have been examined in various experiments and it was found to be the rule that the first appearance of nodules coincided with that of the expansion of the first true leaf. When lucerne is sown under summer glasshouse conditions, in pots of soil or sand, the seedlings are up in from 3 to 5 days, and in 8 to 12 days the first true leak becomes visible. This is at first closed, but in 8 to 12 days from the date of sowing it opens out (fig. 1). The following experiment illustrates the relationship between the opening of the List leak and the appearance of nodules. Lucerne seed, inoculated with nodule bacteria was sown in 12 pots, each containing about 8 pounds of sand, and these were watered with a plant-culture solution free from nitrogen.* Five days after sowing the seedlings were up, and in another 4 the first true leak, still closed, could be seen on most of them. The appearance of nodules and the opening of the first true leaves is shown in fig. 2, where each point represents observations made upon 20 seedlings, 10 from each of duplicate pots. The general agreement in the time of appearance of nodules and in the opening of the first true leaves is evident.