Interference of volunteer corn in growth and chlorophyll fluorescence of bean

ABSTRACT Corn kernels or seeds that remain after harvest can germinate and become a troublesome volunteer plant where bean crops are grown. The objective of this study was to evaluate the effect of time of emergence of volunteer corn on growth parameters, photosynthetic pigments and chlorophyll fluorescence in bean plants, competition for soil and light and light resources. The study was conducted in completely randomised experimental design, in 2×2×2+2 factorial scheme with four replications, involving two bean cultivars in competition with volunteer corn, emerging seven days before and simultaneously with beans, besides the partitioning of the competition by soil and light, just light and two controls without competition. We measured the levels of chlorophyll a, b, total and carotenoids, parameters related to chlorophyll fluorescence and bean growth variables. Volunteer corn was more competitive when it emerged seven days before the beans. When competition was established by light resource, there was a reduction in photosynthetic pigments and morphological variables of the bean plants. When competition by soil and light resources occurred, there was a reduction not only in photosynthetic pigments and morphological characteristics, but also in the chlorophyll fluorescence variables. There were significant correlations between the growth variables of the bean plants and chlorophyll fluorescence, which makes it an important analytical tool for quantifying the stress caused by weeds.