Leaf relative chlorophyll content as an indicator parameter to predict nitrogen fertilization in maize

Abstract

The development of a portable chlorophyll meter (SPAD 502), that takes instantaneous measurements of greenness without leaf destruction, has emerged as a new tool to assess plant N status. This trial was carried out to determine the adequate SPAD readings to predict maize nitrogen needs in four growth stages. The experiment was conducted in the state of Rio Grande do Sul, southern Brazil, during the 1998/99 growing season. Treatments were two maize hybrids (Pioneer 32R21 and Cargill 901) and nine side-dressed nitrogen levels (0, 50, 100, 150, 200, 300, 400, 500 and 600kg ha-1). Nitrogen was side-dressed at the soil surface in four equal doses, according to the levels established on each treatment. The first, second, third and fourth applications were made in the stages of three to four, six to seven, 10 to 11 and 14 to 15 fully expanded leaves, respectively. Urea was used as the N source. Since there was no difference in the SPAD readings among maize hybrids, average values at each stage were used. Readings were carried out in the stages of three to four, six to seven, 10 to 11 fully expanded leaves and at silking. Chlorophyll evaluation samples were taken at two-thirds of the distance from the leaf tip towards the stem. The two upper leaves were sampled on each growth stage before maize flowering. The index leaf (first leaf below the ear) was evaluated during silking. Chlorophyll meter readings above 45.4, 52.1, 55.3, and 58.0 represented the adequate values for the stages of three to four, six to seven, 10 to 11 expanded leaves and at silking, respectively, to achieve high grain yield. The variation in SPAD readings were highest in the early stages of plant growth.

Use of Organic Compost Containing Waste from Small Ruminants in Corn Production

“…They proposed a SPAD index of 55.3 as the critical level for the crop. Therefore, the data obtained in this study for N concentration (which increases along with increasing compost application rates) are consistent with other results in the literature because reach the critical levels proposed by Cantarella et al (1997) for N, and consequently by Argenta et al (2004) for the indirect measurement of chlorophyll.…”

“…A strong relation exists between leaf N level and relative chlorophyll content (SPAD index) in corn plants (Argenta et al, 2001;2004). They proposed a SPAD index of 55.3 as the critical level for the crop.…”

“…The same diagnostic leaves were used, in the middle of the blade and avoiding the central nervure, to measure the relative chlorophyll content (RCC) by the SPAD (soil plant analysis development) index using a chlorophyll meter (Minolta SPAD 502), as previously done by Argenta et al (2004). The concentrations of macro-and micronutrients were measured according to the procedures described in Bataglia et al (1983).…”

Sensibilidade do clorofilômetro para diagnóstico nutricional de nitrogênio no milho

“…Assim, o uso de medidores portáteis que fornecem estimativas indiretas do teor de clorofila permite monitorar rapidamente as respostas do milho a condições variadas de disponibilidade de N nas lavouras (Varvel et al, 1997;Argenta et al, 2004), apresentando boa correlação entre as leituras e as produtividades obtidas (Piekielek & Fox, 1992). Desta forma, o clorofilômetro pode conferir a agilidade necessária ao diagnóstico nutricional e definição de estratégias de manejo do nitrogênio, ainda durante a fase de desenvolvimento da cultura.…”

“…Trabalhos têm visado, também, a relacionar as leituras de determinados estádios fisiológicos e híbridos às produtividades, segundo as doses de N (Argenta et al, 2004), e associadas ao uso de pastagens em sucessão (Godoy et al, 2007).…”