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Abstract
Symptoms of fusarium wilt of tomato were less severe in plants supplied with nitrate-N and greater in those supplied with ammonium-N. Liming with calcium hydroxide decreased disease severity but this effect was negated by high ammonium-low nitrate fertilization. The combination of high nitrate, low ammonium, and lime reduced disease development additively. Fusarium oxysporum f. sp. lycopersici race 2 was more virulent when grown in liquid culture with ammonium than with nitrate as the sole N source.
Tomato (Lvcopersicon esculentum) line E427 contains Fusarium wilt resistant gene I-3 on chromosome 7 and I-2 (and presumably the linked I) genes on chromosome 11. E427 was crossed with `Bonny Best' (i, i-2, i-3) and backcrosses (BC) to `Bonny Best' and F2, seed were obtained. Self pollination of 187 BC and 150 F2 plants were made. Progeny were screened against Fusarium races 1, 2, and 3 and lines with recombinant ratios were self-pollinated and rescreened until homozygous. Five lines were resistant to races 2 and 3 but susceptible to race 1. These had the isozyme band got-2 linked to I-3, RFLP markers linked to I-3 and no RFLP markers linked to I-2. Five lines were resistant to race 1 but susceptible to races 2 and 3. These had the susceptible qot-2 band and no RFLP markers linked to I-3 or I-2. F2 complementation tests of 2 of these lines with `Manapal' (I) indicated they contained I. Three lines were resistant to race 2 but susceptible to races 1 and 3. These had the susceptible qot-2 band, I-2 linked RFLP markers, and no I-3 linked RFLP markers.