Potato yield variation as affected by virus seed degeneration and growth conditions in Tunisia.

Abstract

Virus diseases mainly affect crop growth by reducing the size of the canopy, thus inhibiting the interaction of the incoming solar radiation. Additional yield reduction may be caused by effects on the radiation use efficiency or on the dry matter allocation to the tubers. Research plots were established in 2012 at the Ariana Research Station Institut National de la Recherche Agronomique de Tunisie (INRAT) to determine the effect of seed-borne potato virus Y (PVY) and poor growing conditions on the yield of cultivar Spunta (fairly good resistance to virus PVYn) during the spring crop season (February-June). Five potato seed origins were evaluated. They have five levels of PVY infection: 0%, 2%, 4%, 8% and 50%. They were grown under poor conditions: 50% of the normal fertilization doses, 0% added organic matter and high water salinity (around 4 g/l). The results showed significant general effects of the poor growing conditions on yield reduction whatever the infection level. The differences between yield origins were statistically significant and yields were negatively affected at 8% and 50% infection levels. Thus, the PVY infection levels have a negative effect on yield losses under poor crop management. These findings confirm the previous results recorded in the 2007 season crop. Useful applications in the Tunisian national seed programme were proposed and applied.

Target site mutations underlying insecticide resistance in Tunisian populations of Myzus persicae (Sulzer) on peach orchards and potato crops

“…[3][4][5][6] To reduce the transmission of the aforementioned pathogen, combating virus vectors such as M. persicae remains one of the main challenges for farmers and technicians to meet requirements imposed by Tunisian legislation for certified potato seed production. 7 The aphid M. persicae can display different life cycles depending on winter harshness and the availability of its primary host, Prunus persica (L.) Batsch, where sexual reproduction takes place. 8 Myzus persicae is a host-alternating aphid usually reproducing through holocycly (= cyclical parthenogenesis).…”

“…Indeed, M. persicae is ranked as the most important vector implicated in the epidemiology of the Potato Virus Y (PVY) in Tunisia by far, viewed as the most destructive virus on seed potato production, with transmission efficiency ≤95% and a retention capacity of the PVY tuber necrosis strain (PVY NTN ) ≤3 h under laboratory conditions 3–6 . To reduce the transmission of the aforementioned pathogen, combating virus vectors such as M. persicae remains one of the main challenges for farmers and technicians to meet requirements imposed by Tunisian legislation for certified potato seed production 7 …”