Effect of a weak permanent magnetic field (PMF) with a strength of 403 A/m
on Allium cepa L. bulb sprouting and leaf growth was investigated. Two onio
n varieties to produce green onions (cv. Arzamasskii) and bulb onions (cv.
Ryazanskii) were examined. In addition, the content of chlorophyll, carbohy
drates, and protein in the leaves of the control and PMF-treated plants wer
e determined. The plants of the control group were grown under a natural ge
omagnetic field. The treatment of onions with PMF accelerated sprouting and
extended the length of the fourth leaf in cv. Arzamasskii as much as 40%;
the first leaf in cv. Ryazanskii was lengthened by 25% with respect to its
length in untreated plants. Exposure to PMF increased the number of sprouts
in cv. Ryazanskii and the number of sprout bunches in cv. Arzamasskii. In
addition, PMF elevated the total content of chlorophyll and protein, expres
sed per fresh weight of green onions, but had no effect on the total conten
t of carbohydrates. Conversely, PMF reliably reduced the total content of c
hlorophyll and protein in cv. Ryazanskii. The temperature increase diminish
ed the effects of PMF.