Interference among cotton neighbours after differential reproductive damage

Area of Science:

• Plant ecology
• Plant-insect interactions
• Agricultural science

Background:

• Indeterminate plant species typically reduce vegetative growth during reproduction.
• Insect herbivory causing fruit shedding may alter this balance, promoting vegetative growth.
• Increased vegetative growth could enhance resource acquisition, impacting plant competition.

Purpose of the Study:

• To test if simulated insect-induced reproductive damage in cotton (Gossypium hirsutum) affects plant vegetative growth and competitive interactions.
• To investigate the asymmetric effects of neighbor damage on reproductive success in high- and low-density crops.

Main Methods:

• Cotton crops were grown at high and low densities under three treatments: control (undamaged), uniformly damaged, and non-uniformly damaged.
• Reproductive damage was simulated by manually removing flowerbuds and young fruits to mimic herbivory by Helicoverpa spp. and mirid bugs.
• Vegetative growth (leaf area, dry matter) and reproductive output (fruit number, mature fruit mass) were measured.

Main Results:

• Damaged plants exhibited increased leaf area and vegetative dry matter, particularly at high densities.
• While damaged plants recovered in total fruit number, mature fruit mass was reduced due to limited recovery time.
• Undamaged plants with reproductively damaged neighbors had significantly less mature fruit mass (34-56% reduction) due to increased competition.

Conclusions:

• Simulated reproductive damage stimulates vegetative growth in cotton, potentially increasing competition.
• Differential reproductive damage can negatively impact undamaged neighbors, contrary to benefits seen in studies of herbivory on neighbors.
• Neighboring plants with stimulated vegetative growth due to reproductive loss can reduce the productivity of undamaged neighbors.