L. D. Doneen, J. H. MacGillivray
1943 Plant Physiology  
Moisture is one essential condition for seed germination, and poor germination is very costly to growers. There is, nevertheless, little experimental evidence concerning the effects of different percentages of available moisture (5) on germination; more study of the subject is essential. Since most vegetable seeds are planted at shallow depths, there may be rapid fluctuations of soil moisture around the seed, especially during the warmer months. This condition is common both to the irrigated
more » ... to the irrigated soils of the west and to the soils of humid areas. Though several reports have been published concerning the effect of soil moisture upon germination, in no case has there been accurate measurement of the available soil moisture. LIVINGSTON (3) indicates that seed germination varies with the species of plant concerned as well as with the percentage of soil moisture. According to CooPER (2), several species of forest-tree seeds respond differently to various amounts of supplementary water in addition to natural rainfall. BASS (1), studying the germination of New Zealand spinach, found it to be variable; but the germination was increased when the seeds were dried at intervals during the tests. PARKER and OLIVER (6) studied the combined effects of soil moisture and fertilizer placement on the germination of cabbage, snap beans, and pea seeds. In some treatments there were indications that low soil moisture and method of fertilizer application reduced germination. MAcGILLIVRAY (4) has studied the effect of soil moisture, temperature, and varieties of wheat upon germination. Germination was affected by these three factors. As SHULL (7) has shown, t1e seeds of several plant species will absorb water from solutions much higher in atmospheric pressure than 16 atmospheres (8, 9) which is approximately the pressure of the permanent wilting percentage (5). Xanthium seedj proved able to extract water from a solution whose concentration was 1,000 atmospheres. Methods and discussion A Yolo fine sandy loam (field capacity 15.7 per cent., permanent wilting percentage 8.6 per cent.) and a Yolo clay (field capacity 29.9 per cent., permanent wilting percentage 14.9 per cent.), obtained on the University Farm, were used in this experiment because of their different ability to hold the available water. These soils were air dried, and the moisture contents determined. To obtain a series of soils with different moisture percentages, a quantity of soil was placed in a rotating cement mixer and was sprayed with 1 Mr. EVERETT RYPINSKI and Mr. M. ZOBEL assisted in taking records; Dr. L. D. LEACH cooperated in treating the seed for germination diseases. 524 on August 7, 2015 -Published by Downloaded from
doi:10.1104/pp.18.3.524 pmid:16653870 pmcid:PMC438124 fatcat:o7ifow6afzgfdk4qfqo5fqrjke