Variation of intraspecific interaction along with crop ontogeny and density

• 1、School of Life Science, LanZhou University, LanZhou 730000
• 2、 State Key Laboratory of Grassland and Agro-Ecosystems, LanZhou University, LanZhou 730000

Abstract：Plant density dependence has been a central research area in ecology. The essence of plant density dependence is neighbor plant interaction including positive and negative factors. Previous studies indicated that positive and negative interactions change along with environmental stress gradients. However, it is still unclear whether crop intra-specific interactions change along with ontogeny and density. The experiment of 15 density gradients was conducted for three crop species (soybean, wheat and corn) respectively. Five traits (plant height, basal stem diameter, canopy, biomass and density) were investigated for five times during crop growth. Relative interaction intensity (RII) was calculated based on individual biomass to explore dynamic variation of population positive interaction along with crop ontogeny and density gradients. Analysis results showed that: 1) During crop pre-stage, population positive interaction was detected with medium density, which facilitate plant growth and development; (2) During the middle and late growth stage, interactions between neighbor individuals changed from positive to negative. Meanwhile, competition intensity increase along with increasing density. Self-thinning phenomenon may occur at strong competition intensity. This study could provide experimental foundation for further exploring the mechanism of plant positive/negative interaction variation. Furthermore, the results verified Allee effect and Stress Gradient Hypothesis, and provide scientific foundation for agricultural management.

Keywords： ecology crop interaction competition Relative Interaction Intensity density gradient