Morphological and physiological responses of winter wheat seedlings to nitrogen and phosphorus deficiency.

摘要

Nitrogen (N) and phosphorus (P) deficiencies are major yield limiting factors in many parts of the world. A greenhouse experiment was conducted to study the effects of both N and P deficiency on morphological and physiological responses of wheat cultivars with and without purple coleoptiles in three types of soils. Before the 3-leaf stage, cultivar 'Jagger' with greenish coleoptile showed typical green color in leaves even if grown in soils known to be deficient in N and P. After 3-leaf stage, however, 'Jagger' grown in the same soils exhibited purple on leaves, which was considered a typical symptom of P deficiency. Before 3-leaf stage, cultivar '2174' with purplish coleoptile showed purple on the tips of leaves even if grown in a soil not deficient in P, indicating that the leaf purple color is genetically controlled. Pre-plant P but not N fertilizer application could alleviate the purple severity of young seedlings (before 3 leaf stage). Top-dressing N fertilizer could alleviate the purple severity, but top-dressing P fertilizer could enable the severe purple leaves to return green at older seedlings (5-6 leaf stage), indicating that N and P had different effects on the morphological phenotype. There was a correlation between the purple severity and leaf chlorophyll readings, and N and P accumulation. The various responses of the cultivars to N and P deficiency resulted in significant differences in tiller occurrence and shoot and root dry matter production. Purple coloration is not only a visible symptom due to P deficiency but also a phenotype that can be used to diagnose N deficiency in wheat seedlings.