The Indian Journal of Genetics and Plant Breeding

JN 189 - an elite potato genetic stock with combined resistance to potato stem necrosis tospivirus and potato leafhopper has been registered as unique germplasm by the Plant Germplasm Registration Committee of the Indian Council of Agricultural Research vide Registration No. INGR 07040.

Potato stem necrosis disease (PSND) caused by a tospo-virus is a serious disease and a problem especially in the early planted crop in central and western plains (including plateau). The wide range of symptoms include necrotic and chloretic spots on leaves and stem, veinal necrosis, leaf droop, hanging and cracking of stems and concentric rings spots in affected stems. The disease incidence up to 90% has been recorded in some parts of Madhaya Pradesh and Rajasthan. The disease causes economic losses which varies from place to place and year to year and have been estimated to range from 15–30%. Similarly leafhoppers (Amrasca sp.) are another problem mostly in early potato crop exposed to higher temperature. The important symptom of leafhopper feeding is the typical hopper burn and severe feeding can cause up to 30% reduction in crop yields depending on the variety, location and crop growth phase. Kota region of Rajasthan has been identified as the hot spot for both the diseases. From the repeated screening of potato germplasm at Kota, genetic stock JN-189 has shown consistently high resistance to both the diseases. The culture was shown to attract very little thrips, responsible for spread of PSND, in the field trials conducted at Kota indicating that perhaps the phenomenon of non-preference may be involved to some extent in resistance mechanism.

JN-189 was selected from the F₁ progeny of a cross Kufri Jawahar x S. andigena made in 1974 at Central Potato Research Station, Jalandhar, Punjab. JN-189 is a medium maturing hybrid and produces attractive light purple, oval tubers with medium deep eyes and pale yellow flesh. It has medium height, plant canopy semi-compact, thick stem predominantly purple colour with green pigmentation highly scattered throughout and feebly developed straight wings. The leave structure is intermediate, leaflet width narrow, leaflet coalescence frequency nil, rachis and midrib pigmentation absent and broad leaf width. It has shy flowering, floral stalk light purple, floral stalk-pedicel articulation clearly visible and located above the middle, calyx completely pigmented, bud purple, corolla light purple, corolla shape semi-stellate, anther yellow and cone normally developed, stylar length longer than stamen column and stigma bi-lobed. Sprout of JN-189 are predominantly red purple with white to green secondary colour distributed at the apex, conical in shape, slight pubescence in the base and tip closed. The use of genetic stock JN-189 as a donor parent in developing potato varieties with combined resistance to PSND and leafhoppers will be highly rewarding.