EFFECT OF ABA AND 6-BA ON ACTIVITY OF KEY ENZYMES IN CARBON ASSIMILATION IN MAIZE SEEDLINGS UNDER WATER STRESS Codon Bias of Pyruvate Orthophosphate Dikinase Gene in Amaranthus hypochondriacus Characteristics of CO2 Exchange and Chlorophyll Fluorescence of Transgenic Rice with C4 Genes Photosynthetic Pathway of Three Rattan Species in South China