Gas exchange and leaf metabolism of irrigated maize at different growth stages

Abstract

Net ecosystem exchange (NEE), leaf gas exchange and biochemical traits were investigated in an irrigated maize crop grown under Mediterranean conditions. Sub-optimal irrigation water supply determined a drought stress during the early vegetative growth stage (45–49 days after swing) that decreased NEE. Drought, in the late vegetative stage, also caused a reduction of leaf gas exchange. In the latter period, proline, glycine and serine, as well as sucrose leaf contents increased, while starch, proteins and glucose contents decreased. In the early reproductive stage, the crop experienced a longer dry spell that induced a reduction in canopy as well as in leaf gas exchanges, while protein and free amino acid contents decreased with respect to the late vegetative stage. Both ecophysiological and biochemical data demonstrate a good capacity of cultivar Pioneer PR32D99 to endure the environmental stress, related to Mediterranean summer drought, leading to an elevated dry matter yield at harvest. Photosynthetic apparatus appeared fairly resistant to soil water shortage due likely to the increased leaf content of organic solutes, such as amino acids and soluble sugars.

Keywords:

• Ecosystem gas exchange
• dry matter yield
• leaf gas exchange
• leaf metabolism
• Mediterranean climate conditions
• Zea mays
• L. cv Pioneer PR32D99

Acknowledgements

Thanks are due to Dr. Gaetano Iemma for his kind availability to host the work in his farm; Dr. Vincenzo Carbone for crop management and the useful assistance; Mr. Filippo Busiello for taking care of biometrical determinations; Dr. Bruno Albrecht (Pioneer Hi-Bred Italia S.r.l.) for physiological information about Pioneer PR32D99 hybrid.