Root distribution in potato may explain drought resistance

Potato consumes the most irrigation water in the United Kingdom, so improving crop water use efficiency could be essential for sustainable agriculture. Potato is a relatively drought-sensitive species. However, water saving irrigation techniques can be applied to drought resistant varieties in the later stages to maintain yield despite applying less water. Optimising irrigation practices requires a good understanding of the physiological mechanisms allowing superior performance of drought tolerant varieties. Within the framework of the EU-funded project SIRRIMED, a series of experiments aimed to explain why the Horizon variety is more drought resistant than the commonly used Maris Piper variety. Plants were grown in a polytunnel (to prevent rainfall compromising the experimental design) and irrigation was automatically scheduled based on defined soil moisture thresholds. Both varieties received four different irrigation treatments during the tuber bulking stage (full irrigation (FI), partial root-zone drying with the dry side alternating (PRD-A), partial root-zone drying with sides fixed (PRD-F), and full root-zone drying (DI) in decreasing order of amount of water applied). Treatments that applied 60% and 0% water of FI (PRD-F and DI respectively) decreased tuber yield (by 20% and 50% respectively) in Maris Piper but not in Horizon. This was related to the higher root density of Horizon in deep (> 40 cm) permanently wet soil layers. When plants were grown in 5 L pots in a glasshouse experiment during two months, no differential responses to water deficits of gas exchange, leaf water potential, leaf xylem abscisic acid concentration, specific leaf area, and shoot biomass were found. However, under well watered conditions, root growth during the first month was three-fold higher in Horizon compared to Maris Piper and two-fold after two months of experiment. Water deficit reduced this difference to two-fold in the first month and no difference after two months. Therefore, Horizon seems to maintain yield by rapidly securing access to water stored in deep moist layers. However, this advantage may require particular environmental or cultural conditions to be expressed, such as sufficiently deep soils or adequate water conditions (achieved by irrigation or rainfall) in the early stages after emergence. ? Original title, authors and sources Influencia del vigor de la ra?z sobre la resistencia a la sequ?a de dos variedades de patata Jaime Puertolas Sim?n; Carlos Ballester; David Elphinstone; Ian C. Dodd puertsimon@yahoo.es VII Congreso Ib?rico de Agroingenier?a y Ciencias Hort?colas, Madrid, 26-29 agosto 2013, http://sechaging-madrid2013.org/eposter/?seccion=search???????? Picture of cv Horizon, by http://varieties.potato.org.uk/varieties/view/Horizon ? Key words Patata????????????????? potato? Perske? ??????????????????? ?????? terpomo???????????? pomme de terre???????????? ????????????????????? ?????????????????? aardappel?????????????????????????? ziemniak???????????? batata?? ????????????????? patates??????????????? ??????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????