Canopy Light Environment and Yield of Narrow‐Row Cotton as Affected by Canopy Architecture

Alterations of plant architecture in narrow‐row cotton ( Gossypium hirsutum L.) using management and genetic strategies to improve light penetration into the canopy may increase crop yields. The objective of this study was to quantify how plant architecture changes affect light penetration into the canopy, yield, and yield components of narrow‐row cotton. The study was conducted on a Glendale clay loam soil (fine montmorillonitic, thermic Typic Torrert). Two field experiments were established on 0.76‐m rows in 1995 and 1996. Treatments consisted of the following plant architecture modifications: pruning leaves throughout the canopy, mechanical topping, trimming of branches, and temporarily opening the canopy during boll production. Photosynthetic photon flux density (PPFD) interception and PPFD penetration into the canopy were measured when the canopy was fully developed. Seed‐cotton yield and yield components by plots, fruiting positions, and strata by four main‐stem node groups were obtained. Early canopy modifications simulating plant characteristics such as reduced plant height, short branches, and modified leaf shape increased light availability at the medium and upper part of the canopy. Modified canopy treatments grown at 97 000 plants ha −1 reached high PPFD interception (90–97%), with leaf area index from 3.7 to 5.2. Treatments to increase light distribution in the canopy while maintaining a high PPFD interception increased seed‐cotton yield by 34% due to a 26% increase in number of bolls per square meter. A canopy light environment improved during the first 3 wk after canopy closure (86–107 d after sowing) increased number of bolls per square meter by 33%.