Growth and development of maize ( Zea mays L.) seedlings under chilling conditions in the field

Abstract

Maize inbred lines of different origins were grown in spring (for 2 years at early and usual sowing dates) in northeastern Switzerland (latitude 47°27′ N; 550 and 720 m a.s.l.) until five to six leaves were fully developed. Averaged over all observation periods, the group of inbred lines used in hybrids for cool temperate regions (CT lines) showed better heterotrophic and autotrophic shoot growth and faster development than the group of lines adapted to warm tropical regions (CS lines). The more efficient autotrophic shoot growth of CT lines was expressed by higher rates of relative growth (RGR) and relative leaf area expansion (RLGR) and was related to a higher net assimilation rate (NAR) and a lower leaf area ratio (LAR). CT lines had better radiation use efficiency (RUE), higher rates of net photosynthesis ( P N), and lower specific leaf area (SLA) than CS lines. The greater RGR and RLGR of CT line Z 7 as compared to the CS line Penjalinan were related to a higher assimilation rate but not to a better use of carbohydrates; in Z 7 the balance between assimilation production and use resulted in a greater accumulation of soluble carbohydrates and starch. Genotypic variability existed for most growth parameters and was greatest for NAR. Growth responses of inbred lines under field conditions in spring were influenced mainly by temperature. Of all parameters, NAR was correlated best with temperature. Under decreasing temperature, RGR, RLGR, the rate of leaf appearances (RLA) and NAR decreased, whereas LAR, leaf area partitioning (LAP), and SLA increased slightly. The soluble carbohydrate content of Z 7 and Penjalinan also increased. RUE showed the best correlation with the daily minimum air temperature. Within the temperature limits of this experiment, no significant interactions were found between inbred line and temperature.