Effect of soil type, salinity, and allelochemicals on germination and seedling growth of a medicinal plant Lepidium sativum L.

The present work was conducted to elucidate the effect of soil type, salinity stress and allelochemicals from alfalfa on the germination efficiency, seedling growth and photosynthetic pigments of Medicago sativa L. The highest germination rate (69.9%) was recorded for seeds cultivated in sandy soil followed by that of clay soil (42%) and then loamy soil (19%). The maximum germination rate was attained at 50 mM NaCl concentration level, after that the values were decreased as the salinity levels increased. The maximum lengths (cm) of plumule and radicle and their growth rates (cm/day) were obtained at control level and found to decline significantly as the salinity increased. Aqueous extracts of alfalfa reduced the germination rate, radicle and plumule growth and seedling dry weight of L. sativum. However, chlorophyll and carotenoid content was increased, their maxima were recorded at 50% concentration level. The chlorophyll a/b ratio attained its maximum at the full strength concentration level.