Resistance to septoria leaf-spot (Septoria lycopersici) and buckeye fruit-rot (Phytophthora nicotianae var parasitica) of tomato (Lycopersicon esculentum)

An experiment was conducted during 2000 and 2001 to screen 80 lines of tomato (Lycopersicon esculentum Miller nom. cons.) for resistance against septoria leaf-spot (Septoria lycopersici Speg.) and buckeye fruit-rot [Phytophthora nicotianae B.de Hann. var parasitica (Dastur) Waterhouse] under natural epiphytotic conditions at Nauni, Solan (Himachal Pradesh). The lines 'EC 401927' and 'CLN 5915-206-D-4 2-2-0' showed moderate degree of resistance to septoria leaf-spot (13.00 and 20.67% respectively), while the line 'EC 129602' recorded the minimum (6.48%) buckeye fruit-rot incidence and rated as moderately resistant to fruit-rot under field conditions. However, gene effects along with heterosis for septoria leaf spot and buckeye fruit-rot were studied in 45 cross-combinations involving 10 parental lines. The parent 'EC 401927' possessed moderate degree of field resistance (15.10%) to septoria leaf-spot, while 'CLN 5915-206D(4) 2-2-0' had minimum (20.16%) fruit-rot incidence and rated as moderately susceptible. The susceptibility reaction for both the diseases was primarily governed by non-additivc gene actions. The genotypes 'EC 401927' and 'CLN 5915-206D(4) 2-2-0' appeared good general combiners for inducing lower level of disease intensity to leaf-spot and buckeye fruit-rot respectively. Crosses 'CLN 1462A' x 'CLN 1466J' and 'CLN 5915-206D(4) 2-2-0' x 'CLN 1462A' were identified as superior combinations on the basis of their per-se performance and high heterotic response over the better parent for septoria leaf-spot and buckeye fruit-rot respectively. These combinations were also superior to both the checks ('Solan Sagun' and 'Naveen') for disease reactions and other horticultural traits.