Adubação nitrogenada e potássica na severidade da antracnose em dois cultivares de milho

Abstract

Nitrogen and potassium fertilization influence on anthracnose severity in two corn cultivarsThe nutritional balance may contribute to increase plant disease resistance. With the aim of evaluating the interaction of nitrogen and potassium fertilization on severity of leaf anthracnose and mineral nutrition of maize, two experiments were installed in a greenhouse using two cultivars of corn, DAS 2B710 (moderately resistant to disease) and BRS 1010 (susceptible). Five doses of N (75, 150, 300, 600 and 1200 mg dm -3 ) and K (63, 125, 250, 500 and 1000 mg dm -3) were applied. The experimental design for each cultivar was completely randomized in a 5x5 factorial scheme, with 25 treatments and four replications. Each vase with four plants consisted of one experimental plot. The dosage of N and K were distributed in 4 applications at intervals of 10 days from sowing, for both cultivars. At 21 days after sowing, plants were inoculated and taken to a moist chamber with photoperiodic treatment of 16 hours in darkness for 3 consecutive days. After the inoculation, the severity was assessed daily for 11 days. At 43 days after sowing, the aerial Recebido para publicação em 02/04/2012 e aprovado em 19/03/2013 1 Engenheiros-Agrônomos, Doutores. Embrapa Milho e Sorgo, Rodovia MG 424, Km 65, Sete Lagoas, Minas Gerais, Brasil.

Silicon in plant disease control

“…However, if not applied in balance with other cations in the soil, it can compete with Mg 2+ , K + and NH 4+ for the same absorption sites, render the plants deficient in these minerals and unbalance plant nutrition. Studies in this line were carried out in coffee (Garcia Junior et al, 2003), soybean (Pinheiro et al, 2011) and corn (Carvalho et al, 2013).…”

Identification of sources of resistance to anthracnose stalk rot in maize

“…The red mark is a kind of background to resistance; though there are some red susceptible genotypes. The simple hybrid 2B710 has an effective resistance level and showed red pigmentation in the stalk surface and leaves veins, which appears in some genotypes due to the production of carotenoids and flavonoids (GARDINGO, 2008;COSTA et al, 2010b;COTA et al, 2010;COTA et al, 2012;CARVALHO et al, 2013). This genotype has been used as a positive control in studies investigating anthracnose stalk rot resistance, as well as for genotype selection in germplasm banks; in addition, this hybrid has shown good agronomic features in many studies (COTA et al, 2012;CARVALHO et al, 2013;ZUCARELI et al, 2013, COSTA et al, 2014.…”

“…Resistant cultivars carry genes with resistance to stalk rot infection, which are transferred via a quantitative inheritance mode, with the predominance of an additive genetic effect (CARSON & HOOKER, 1981;BADU-APRAKU et al, 1987;TOMAN & WHITE, 1993;BERGSTROM & NICHOLSON, 1999;PALAVERSIC et al, 2009;MATIELLO et al, 2012). Maize genotypes showing different levels of anthracnose stalk rot resistance have been described in germplasm banks; examples of such genotypes are the following: MP305, DE811ASR (JUNG et al, 1994, BROGLIE et al, 2006FREY et al, 2011);DW1035 (TOMAM & WHITE, 1993; A556, A638, Oh43, R177 (CARSON & HOOKER, 1981); RD6502 (BADU-APRAKU et al, 1987);Bc19064 (PALAVERSIC et al, 2009);CML52 (CHUNG et al, 2011);Das2, Das64 (MATIELLO et al, 2012); H8664 (MATIELLO et al, 2013); 2B710 (GARDINGO, 2008;COSTA et al, 2010b;COTA et al, 2010;CARVALHO et al, 2013). However, in practice, the resistance levels of these genotypes remain weak, and information on effective resistance sources is lacking.…”

Nitrogen and potassium fertilization on the yield and intensity of the maize white spot

“…Still in relation to the corn, Carvalho et al (2013), studying the interaction of doses of N (75, 150, 300, 600 and 1200 mg dm -3 ) and K (63, 125, 250, 500 and 1000 mg dm -3 ) in pots, and two cultivars, one moderately resistant and the other highly susceptible, report an interaction between N and K. According to these authors, for both cultivars, the largest leaf area injured (LAI) was obtained in the treatment with the lowest doses of N and K (75 mg dm -3 de N and 63 mg dm -3 of K, respectively. The increasing of the doses of N-NH 4 + reduced the K content in the upper canopy, for both cultivars.…”