Relationship between physiological response of French beans of different age to Meloidogyne incognita and subsequent yield loss

Abstract

A study was made of the effect of a single generation of the root-knot nematode Metoidogyne incognita on the growth of potted French bean plants (Pliaseolus vulgaris) inoculated at different stages of plant maturity. In separate experiments, 3-, 11-and 13-day-old plants were inoculated before primary leaf expansion (BPLE), at the appearance of trifoliate leaves (TRIF) and at the flower bud (BDS) stages respectively, with 0, 2000, 4000 or 8000 second-stage juvenile nematodes and maintained in a growth chamber under controlled conditions. The photosynthetic rate of the plants inoculated at the TRIF and BDS stages decreased significantly with increasing inoculum level 7 days after inoculation. Although the respiration rate did not significantly change throughout the experimental period, the ratio of photosynthetic to respiration rate decreased significantly with increasing nematode inoculum level and duration of infection. Chlorophyll content, plant dry weight and the numbers of buds, flowers, pods and seeds were significantly lower in infected plants than in the controls; this effect increased with increasing levels of nematode inoculum for all three plant stages. The leaf area was significantly smaller only when nematode infection occurred at the BPLE stage. The plants which were youngest at the time of nematode infection produced the lowest yield; this appeared to result from the effect of nematodes on photosynthesis and related physiological processes.

Fertiliser use efficiency of soybean cultivars infected with Meloidogyne incognita and Pratylenchus penetrans

“…The time of photosynthesis measurement was designed to coincide with the approximate completion of the nematodes' life cycle, and when M. incognita has been shown to have the most impact of its host within a single generation (Melakeberhan et al, 1986). In order to minimise errors driven by small differences in the amount water present in each pot at the time of measurements, all plants were watered to saturation with their respective solutions 1 h before measurements commenced.…”

Crescimento de três variedades de cana-de-açúcar submetidas a estresse hídrico associado à Meloidogyne incognita

“…Além do mais, promove redução da altura da planta, restrição ao surgimento de novas folhas e senescência foliar, queda no número de perfilhos, colmos mal-conformados e murcha temporária durante períodos quentes do dia, além de influenciar no acúmulo de matéria seca (Melakeberhan et al, 1986;Hemaprabha et al, 2004).…”

Interaction Between Golden NematodeGlobodera Rostochiensis(Woll.), Behrens and Soil Saprophytic Fungi - Its Influence on The Processes of Gaseous Exchange and Crop Yield of Potato (Solanum TuberosumL.)

“…A decreased rate of photosynthesis, which in consequence leads to a reduced yield, was also demonstrated by Lorenzini et al (1997), for tomato infected by Fusarium oxysporum f. sp. lycopersici and Verticillium albo-atrum, by Franco (1980), for potato infestation by G. rostochiensis, and by Melakeberhan et al (1985Melakeberhan et al ( , 1986, for bean infected by Meloidogyne incognita.…”