Variation in growth and accumulation of N, K+, Ca2+ and Mg2+ among barley cultivars exposed to various nutrient regimes and root/shoot temperatures

Six cultivars of barley ( Hordeum vulgare L., cvs Salve, Nürnberg II, Bomi, Risø 1508, Mona and Sv 73 608) were exposed for three weeks to combinations of high and low mineral supply and differential root/shoot temperature. For all the parameters tested fresh and dry weights, contents and levels of N, K⁺, Ca²⁺ and Mg²⁺, and influx of Rb⁺(⁸⁶Rb)] the cultivar differences were influenced by the mineral supply, the root temperature and the age of the plants.
The cultivar differences in N nutrition of three-week-old plants could partly be attributed to variation in root size, uptake of N and in use-efficiency of the element. The cultivar variation in root-shoot partitioning of N was small, except when low mineral supply was combined with a low root temperature. Similarly, cultivar differences in contents of K⁺, Ca²⁺ and Mg²⁺ were influenced by variation in uptake, use-efficiency and root/shoot partitioning of the elements. Low root temperature increased cultivar variation in K⁺, Ca²⁺ and Mg²⁺ partitioning.
The modern cultivar Salve was compared with Nürnberg II, which is derived from a German land race. Nürnberg II performed better than Salve when low root temperature and restricted mineral supply were combined. Otherwise Salve grew better, partly due to a more efficient use of N.
Two high-lysine lines, Risø 1508 and Sv 73 608, were compared with their mother lines Bomi and Mona. The differences obtained revealed no general effect of the high-lysine genes on growth and mineral nutrition of up to three-week-old barley plants.