Phosphorus and nitrogen effects on the freezing tolerance of Norstar winter wheat

Abstract

To increase the probability of winter survival, it is recommended that winter wheat (Triticum aestivum L.) be sown into standing stubble from a previous crop, which acts to trap an insulating layer of snow. Therefore, to replenish nutrients used by the previous crop and to obtain optimum yields of winter wheat, these soils have to be fertilized with N and P. The objective of this study was to determine the effect of N and P, alone and in combination, on the freezing tolerance of Norstar winter-wheat seedlings in the fall and in early spring and during storage at −4 °C throughout the winter months. None of the fertilizer treatments had an effect on the freezing tolerance of the seedlings in late fall, however, P in combination with N decreased freezing tolerance in March and April, with the effects being more pronounced at high rates of P. Seedlings sampled from the field in early May were similar in freezing tolerance, irrespective of the level of fall-applied N and P. Both shoot and root growth of seedlings collected in the spring were enhanced by P fertilization in combination with N. Fall-applied P increased the level of tissue N and P, while applications of N increased the level of tissue N of seedlings sampled in late fall. Key words: Winter wheat, nitrogen, phosphorous, freezing tolerance