Variation in Early Vigor between Wheat and Barley

Lóopez-Castañeda, C.; Richards, R. A.; Farquhar, G. D.

Variation in Early Vigor between Wheat and Barley

1995

Lóopez-Castañeda, C. | Richards, R. A. | Farquhar, G. D.

In dryland Mediterranean-like climates, barley (Hordeum vulgare L.) generally has higher grain and biomass yields than other temperate cereals. The advantage of barley compared with wheat (Triticum aestivum L.) is associated with barley's faster leaf area growth during vegetative development. Experiments were conducted in a glasshouse (average 25/15°C) and outdoors (average 17/5°C) to determine the traits associated with barley's greater early growth. Five cultivars each of barley and wheat were grown in large pots. Five harvests were made from the time there were about 2 leaves on the main stem to the time plants had about 4.5 leaves on the main stem. The weight of the caryopsis of all seeds sown was 35 mg. Barley produced ≈40% more aboveground biomass and two times greater leaf area than wheat by the two-leaf stage. Barley had a 17% faster average leaf appearance rate and a 35% faster average tiller appearance rate than wheat but there was no evidence that either contributed to the differences in vigor between the two species. The relative growth rates for biomass and leaf area were also similar in the two species, although it was achieved in different ways. The average net assimilation rate (NAR) was 25% greater in wheat than in barley in both experiments, whereas the average leaf area ratio (LAR) was 23% higher in barley. Variation in specific leaf area (SLA) was largely responsible for the variation in NAR and LAR in both the glasshouse and outside. Factors between germination and the appearance of the second main stem leaf must be responsible for the greater early vigor in barley compared with that of wheat.

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