Agro-physiological and growth response to reduced water supply of somatic hybrid potato plants (Solanum tuberosum L.) cultivated under greenhouse conditions

Potato seed production from in vitro multiplication processes requires different steps, starting from greenhouse cultivation of plants and production of the first generation of tubers (minitubers). These tubers are then used as seeds in the first field culture conditions, which is followed by a second field culture using the previous tubers as seeds. The insect-proof greenhouse culture of potato plants requires regular watering and an adequate fertilization process. In this context, we focused in this report on the greenhouse culture conditions of two intraspecific somatic hybrids that previously showed improved resistance to Potato Virus Y and to Pythium aphanidermatum infection. Three different culture conditions were tested: a seasonal culture submitted to full irrigation (IR100) or to 50% irrigation (IR50) and off-seasonal culture. The effects of the moderate water deficit during the culture period on plant growth and tuber yield were investigated. During the different culture periods, physiological, biochemical and agronomical parameters were followed. The greenhouse experiments were applied on two commercial varieties (Nicola and Spunta) used as control in addition to the two somatic hybrid lines (CN1 and CN2). Hybrid plants exhibited better plant growth and higher yields of tubers than the commercial varieties. Under moderate water supply plants from hybrid lines showed higher tuber quality than commercial lines. Indeed, the highest levels of dry matter, starch, protein and lipid contents were measured in CN1 tubers in the full irrigation regime. Similarly, in the off-seasonal culture, the CN1 and CN2 tubers exhibited the highest dry matter content. The 50% reduction of irrigation rate slightly affected the starch, protein and lipid contents of the different plant lines. However, the CN1 hybrid tuber content in starch and reduced sugars remained higher than the other tubers.