Seedling Development of Adapted and Exotic Maize Genotypes at Severe Chilling Stress

Abstract

Stamp, P. 1987. Seedling development of adapted and exotic maize genotypes at severe chilling stress.—J. exp. Bot. 38: 1336–1342. Four maize genotypes from North West Europe (NWE), tropical highlands (TH) and tropical lowlands (TL) were grown at 24°C until full expansion of the second leaf. Seedlings were subjected to 5°C during 2 d thereafter, with or without a previous conditioning phase at 10°C for 4 d. After stress, seedlings were allowed to recover at 24°C for 5 d. All genotypes resumed high growth rates after stress, highest values were observed for one TH genotype. Previous conditioning was most effective in TL and least effective in TH genotypes. In spite of similarities between patterns of growth rates and rates of leaf expansion the latter process was less promoted by previous conditioning. The green area of the second leaf was little impaired by 5°C in most genotypes. But without conditioning the TL genotype lost about 40% green leaf area, mostly during the recovery phase. Conditioning did not prevent losses in relative turgidity of second leaves during stress but it enabled sensitive genotypes to resume normal values during recovery. Losses in phosphofructokinase activity occurred in the TL genotype during stress and recovery, and in TH genotypes during recovery while the activity was stable in the NWE genotype. A close relationship between this enzyme activity and growth rates was not observed. Although one TH genotype had the best chilling tolerance on the whole plant level the expression of some physiological and biochemical leaf traits was inferior to the adapted NWE genotype.