The effect of reproductive effort on root dynamics and physiology in Vitis labruscana Bailey cv. Concord grapevines was investigated in a vineyard in Fredonia, NY, USA. Grapevines were thinned to achieve target fruit crops of 100%, 75%, 50% and 25% of full cropping (~18.6 kg/vine) to establish different levels of reproductive effort. Actual three-year crop averages were 100%, 75%, 58% and 45% of full crop. The lowest level of reproductive effort resulted in a 30-56% greater aboveground vegetative growth compare to the other treatments. Arbuscular mycorrhizal colonization was found to be 36%-50% higher in the 25% treatment than in the other treatments, although colonization in all treatments was >50% root length colonized. Fine roots also tended to be higher in total nonstructural carbohydrate concentration in the 25% treatment than in the 100% treatment, although not significantly. In contrast, root production, lifespan, vertical and horizontal distribution and respiration were generally not decreased by an increase in reproductive effort. Thus, we conclude that Concord grape has remarkable ability to maintain root system functions under sustained high levels of reproduction.
