Under Bulgaria's climatic conditions, both initial growth and development of maize plants often undergo suboptimal temperatures. The aim of this study was to determine the effect of low temperatures on both the initial growth and mineral nutrition of plants of two maize hybrids – the new hybrid Kneja 307 and the P9528 hybrid. Experiments were conducted with young plants grown in climatic modules as hydroponic culture in pots filled in with modified Hoagland nutrient solution. After the occurrence of the 3rd leaf, the maize plants were divided into two groups and maintained for 7 days under two temperature regimes - optimal (control) 25 ± 1/20 ± 1ºC (day/night) and suboptimal - constant temperature (10 ± 1ºC). At the beginning and at the end of the experimental period biometric measurements were performed as well as the relative growth rates of the plants (RGR) were calculated. In addition, the total content of the elements nitrogen, phosphorus and potassium in the plant organs was determined. It was found that a low temperature significantly suppressed the biometric parameters and diminished RGR by 36–38%. There were no significant differences in the tolerance to low temperatures between the hybrids. Low temperature had no significant impact on the nitrogen content, but it lowered the content of phosphorus and potassium in the organs of the maize plants. The young plants of the two maize hybrids showed some differences in their tolerance to the temperature factor, indication for which were the two biometric parameters- root length and fresh mass of plants.
Influence of low temperatures on the growth and macronutrient content in young maize plants