Water availability and root-knot nematode management alter seedcotton yield through similar effects on fruit distribution patterns

Authors: SNIDER, JOHN - University Of Georgia; Davis, Richard; EARL, HUGH - University Of Georgia; Timper, Patricia - Patty

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2019
Publication Date: 1/15/2019
Citation: Snider, J.L., Davis, R.F., Earl, H.J., Timper, P. 2019. Water availability and root-knot nematode management alter seedcotton yield through similar effects on fruit distribution patterns. Field Crops Research. 233:88-95. https://doi.org/19.1016/j.fcr.2019.01.008.
DOI: https://doi.org/10.1016/j.fcr.2019.01.008

Interpretive Summary: Both root-knot nematode (RKN) infection and inadequate amounts of water reduce yields in many cotton growing regions of the southern United States. The objective of the current study was to determine whether seedcotton yield (the weight of lint plus seeds) limitations due to drought and RKN infection were brought about through similar effects on yield components and boll distribution patterns. To this end, yield component and boll distribution assessments were conducted for a seven-year study in Tifton, Georgia that included three irrigation treatments and two fumigant treatments to manage nematodes. Seedcotton yield was strongly affected by year, irrigation treatment and fumigant treatment, but no interactions were observed between the two factors, which shows that the yield limiting effects of nematode infection could not be mitigated by providing more water. Yield declines due to nematode infection and water deficit were primarily driven by a decline in total boll density. Yield distribution patterns revealed that water deficit negatively affected boll numbers for all branch types and fruiting branch positions and the mainstem node of peak boll distribution was lower under drought. This was also the case for nematode infected plants (except that boll density at position two was not affected by fumigation). One notable difference between drought and nematode effects was that the relative decline in boll density due to nematodes was roughly the same for all branches and fruiting sites when declines were observed, whereas the relative decline in boll density on branches for drought-stressed plants was greater at positions further from the mainstem.

Technical Abstract: Both root-knot nematode (RKN) infection and water deficit negatively affect yields in many cotton growing regions of the southern United States. The objective of the current study was to determine whether seedcotton yield limitations due to drought and RKN infection were brought about through similar effects on yield components and boll distribution patterns. To this end, yield component and boll distribution assessments were conducted for a seven-year study in Tifton, Georgia that included three irrigation treatments and two fumigant treatments to manage nematodes. Seedcotton yield was strongly affected by year, irrigation treatment and fumigant treatment, but no interactions were observed between the two factors, illustrating that the yield limiting effects of nematode infection could not be mitigated by providing a water-replete condition. Yield declines due to nematode infection and water deficit were primarily driven by a decline in total boll density. Yield distribution patterns revealed that water deficit negatively affected boll numbers for all branch types and fruiting branch positions and the mainstem node of peak boll distribution was lower under drought. This was also the case for nematode infected plants (except that boll density at position two was not affected by fumigation). One notable difference between drought and nematode effects was that the relative decline in boll density due to nematodes was roughly the same for all branches and fruiting sites when declines were observed, whereas the relative decline in boll density for drought-stressed plants was greater at sympodial positions further from the mainstem.