Activity of Barley Seedling Roots as Measured by Strontium Uptake
1973
Soileau, J. M.
Root activity at various depths in soils is important in relation to effective use of lime and fertilizers by crops. Barley (Hordeum vulgare L.) seedlings were grown in presplit cylinders in the greenhouse to measure root activity in three 10-cm soil depth zones and to estimate daily rates of nutrient uptake. Twenty-five seedlings were planted per 15 ✕ 30 cm cylinder containing 6.5 kg of soil. SrCO₃ was applied to one of the 10-cm layers of soil, and the plants were sequentially harvested for measurement of Sr uptake and root growth. A substantial number of roots penetrated to the 20 to 30 cm zone in 14 days. After 31 days, total root length was 662 m, distributed uniformly throughout the soil column. Root activity index calculations based on Sr uptake in tops per unit length of roots indicated that the 0 to 10 cm layer was the most active root zone over a 31-day period. Total uptake of St, Ca, Mg, and P by barley tops increased linearly with increase in total root length or dry weight. Mean daily rates of uptake of Ca, Mg, and P (μg/m of roots/day) showed a general decrease with time. Milliequivalent concentration ratios of Ca to Sr in barley tops were much lower than ratios of exchangeable Ca to exchangeable Sr in the soil.
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