Cotton boll formation and fiber quality when grown alongside perennial groundcover crops

The incorporation of perennial groundcover crops (PGCC) into cotton (Gossypium hirsutum L.) systems may provide similar benefits to annual cover crops with fewer associated costs, but their effects on boll production and fiber quality have not been investigated. This study assessed the effects of growing PGCC species on end-of-season boll formation, retention, position, distribution, and fiber quality compared to annual cover crops or fallow systems. Over 2 years, cotton was interseeded and grown in four cover crop treatments as follows: (1) terminated weedy fallow, (2) terminated annual ryegrass (Lolium multiflorum Lam.), (3) a living 1:1 mix of perennial red clover (Trifolium pratense L.) and white clover (Trifolium repens L.), and (4) a living 2:1:1 mix of ryegrass, red clover, and white clover. Post-harvest plant mapping was conducted on plants from outside of harvested rows in each plot to determine final boll set, position, and canopy distribution as well as sympodial and monopodial branching. Fiber quality was also assessed via high volume instrument. Results indicated that the presence of clovers increased boll density lower in the canopy while also increasing the number of position 2 bolls compared to the fallow system, and that growing perennial clovers alongside cotton reduced formation of monopodial shoots. Presence of perennial clovers also reduced the incidence of short fibers in cotton under drought conditions, but did not alter any other fiber quality parameters over the study period. These findings further support the use of PGCC as a mechanism to improve adoption of cover crops in cotton production.