The environment temperature affects post-germination growth and root system architecture of pea (Pisum sativum L) plants

Seeds of ten different pea genotypes were sown in styrofoam transplant trays filled with vermiculite and kept in two different growth chambers, respectively at air temperatures of 10 °C and 15 °C. In both chambers the relative humidity was maintained at 90%, PPFD 180 μmol m⁻² s⁻¹and the photoperiod 12 h. At DAS 15 and 31, ten plant of each treatment were selected randomly, dissected and separated into roots and shoots. Root system was scanned and acquired root images were analyzed. Subsequently, all plant organs were dried (65 °C, 48 h) and weighed separately. Significant genetic variation was identified regarding root traits. Rather than with the drought resistance and N foraging capability the genetic variation was associated with P foraging capability of the root system. Despite significant genotype differences, root traits were remarkably affected by environment temperature. The suboptimum temperature reduced growth and delayed root development processes. The decrease of temperature from 15 °C to 10 °C was followed by a significant decrease in the dry matter of plant, but the ratio of root dry matter to plant dry matter was significantly increased. The total root length was also significantly decreased, almost totally due to a significant decrease in the lateral root length. Only slight effects were found regarding tap root length. Water and nutrient uptake capabilities of pea plants were enhanced under optimum temperature conditions, mostly due to increased lateral root density and extended root branching zone deeper into the soil. Either the differences in lateral root (LR) density or the length of branching zone seems to be related with the effects of temperature to the length of development time from LR initiation to LR emergence.