Variability and factors of variation of crude protein content in whole maize plant

Abstract

We used a database containing 16 368 data obtained on whole plant maize, and literature data to evaluate the extent and factors of variation of crude protein (CP) content. CP content of whole plant maize at harvest was 7.7 + 0.7 % DM on average, and varied between 4.7 and 10.5 % DM. CP and ashes contents were significantly correlated, involving a relationship between N and minerals absorption by plant. These variations in CP content had several causes. It decreased to a low extent with maturity stage, 0.20 percentage unit between dough-flint and flint stages. Variability due to ’milieu’ (location x year) was higher than variability due to variety (standard deviation of 0.65 and 0.47 percentage unit, respectively). The negative relationship between CP content and yield sometimes observed might express an indirect negative effect of selection on maize CP content, but this relationship was not systematic. Ensiling involved a passive increase in CP content (0.40 percentage unit) with large modifications of biochemical composition of proteins.