Sand Abrasion Injury and Biomass Partitioning in Cotton Seedlings.

Wind blown soil particle abrasion negatively impacts millions of hectares of crops annually.  The goal of this study was to examine the effects of wind and wind blown sand abrasion damage on cotton (Gossypium hirsutum L.) seedling biomass partitioning to leaves, stems, and roots. Seedlings of three cotton cultivars were exposed to no wind (untreated controls) or sand abrasive flux densities of 0, 0.1, 0.25, 0.35 and 0.5 g cm^-1 width s^-1 at a wind velocity of 13.4 m s^-1 in a suction-type laboratory wind tunnel.  Plants were destructively sampled at the time of the sand abrasion treatment and also at approximately 2 and 4 weeks after exposure.  These three sampling dates provided two time intervals for assessing the amount of plant damage and re-growth using classical growth analysis. With increasing sand abrasive flux density, whole plant, leaf, stem, and root biomass as well as leaf area were all reduced in both harvest intervals (P ≤ 0.05). Although small significant differences in leaf area ratio (LAR) were found among cultivars and sand abrasion treatments, net assimilation rate (NAR) accounted for 96 and 75% of the variability in relative growth rate (RGR) in the first and second harvest intervals, respectively. Increasing plant damage caused by sand abrasion treatment resulted in preferential biomass partitioning to the damaged stems rather than roots during the first harvest interval while a much more stable allometric allocation of biomass among plant organs was observed in the second harvest interval.