Yield and quality responses of carrots (Daucus carota L.) to water deficits

There is little quantitative information available on the responses of carrots (Daucus carota L.) to water deficits. We tested the hypothesis that root yield decreases with increases in the maximum potential soil water deficit (D-Omax, mm). Field crops of carrot (Chantenay Red Core) were grown under a rain-out shelter near Lincoln, New Zealand, using trickle irrigation to achieve six treatments that differed in the timing (early-, mid- and late-season) and intensity (moderate and high) of water stress. There were also unirrigated and fully irrigated (minimal water stress) treatments. Total biomass and root yields declined linearly with increasing D-Omax, supporting the hypothesis under test. Storage root diameter, but not length, also decreased, so that process-grade packouts of roots fell sharply with D-Omax. There was no significant relationship between root soluble solids concentration and D-Omax. Minimising water deficits is crucial for achieving high yields of quality carrots.