The response of a salt-resistant and a salt-sensitive wheat cultivar under salinity stress to foliar applied KNO3 was studied in China. Both cultivars were sown in vermiculite boxes. Control seeds were germinated and raised in Hoagland nutrient solution (0 mM NaCl, 6 mM KNO3). In the saline treatments, seeds were exposed to 100 mM NaCl. Foliar applied KNO3 (10 mM; 1 g KNO3/L) was applied at the wheat heading stage for three consecutive days. A randomized block of four treatments and two different winter wheat cultivars with 6 replications per treatment was designed.
Although, the wheat grain yield of both cultivars was statistically significantly increased due to the foliar application of potassium nitrate under saline conditions. The salt-resistant cultivar was more productive under salinity stress than the salt-sensitive cultivar (Figure 1).
Figure 1. Effect of foliar KNO3 on wheat grain yield under saline conditions for two winter wheat cultivars (cultivars are analyzed separately, P<0.05):
Foliar application at the heading stage also statistically significantly elevated flag-leaf chlorophyll concentration. This enhanced the gas exchange under salinity stress, as well as the leaf-area index, spike length and the plant height. Grain quality characteristics were also improved in the salt-resistant cultivar by foliar application of potassium nitrate under saline conditions, as compared to the salt-sensitive cultivar. Their findings suggest that cultivating the salt-resistant wheat cultivar combined with foliar application of KNO3 at heading stage may alleviate salinity injuries and produce higher grain yield and better grain quality under saline conditions.