Thermal requirements and population dynamics of root‐knot nematodes on cucumber and yield losses under protected cultivation

Abstract

Several studies were carried out to determine (i) thermal requirements for development, egg production and emergence of juveniles, and completion of the life cycle of Meloidogyne incognita and Meloidogyne javanica on cucumber, (ii) the maximum multiplication rate and the equilibrium density of root-knot nematodes on cucumber and yield losses in pot and plastic greenhouse experiments, and (iii) the relationships between relative leaf chlorophyll content (RLCC) and relative cucumber dry top weight biomass (RDTWB) in relation to increasing nematode densities at planting (P-i) in pot experiments. Thermal requirements of M.incognita and M.javanica on cucumber did not differ, irrespective of the biological stage. In the pot experiments, M.javanica completed one generation. The maximum multiplication rate (a) was 833, and the equilibrium density (E) varied according to the effective inoculum densities. The relationship between RDTWB and P-i fitted the Seinhorst damage function model. The RLCC value at 40 or 50days post-inoculation also fitted the damage model and was related to RDTWB. In greenhouse experiments, conducted from 2009 to 2012, M.incognita completed three generations. The values for a and E were 1147 and 625second stage juveniles (J2) per 250cm(3) soil, respectively. The tolerance limit was below zero, and the minimum relative yield ranged from 012 to 034.Postprint (published version

Population dynamics of Meloidogyne incognita on cucumber grafted onto the Cucurbita hybrid RS841 or ungrafted and yield losses under protected cultivation

“…As a result, nematode-induced changes in both plant water and nutrient status led to a decrease in net photosynthetic rate. Therefore, in agreement with previous studies, nematode infection caused a reduction in leaf chlorophyll content (Audebert et al 2000 ;Ahmed et al 2009 ;Khan and Haque 2011 ;Giné et al 2014 ;López-Gómez et al 2015 ) as well as in photosynthetic activity (Loveys and Bird 1973 ;Melakeberhan et al 1985 ) as suggested by the negative relationship between Pi and net photosynthetic rate. In addition, for both grafted or ungrafted cucumber plants, relative changes in yield were also related to the relative variation in both R / [R x R ] and net photosynthetic rate, confirming previous results in which relative dry top weight of cucumber or zucchinisquash biomass (López-Gómez et al 2015 ) was related to relative leaf chlorophyll content.…”

“…The results of this study show that values of a and E of M. incognita on ungrafted cucumber cv. Dasher II cropped in spring-summer (April to July) were lower than those reported by Giné et al ( 2014 ) when cucumber was cropped in summer-autumn (July to November). Similar results were reported for M. incognita on zucchini-squash ) and for M. artiellia on chickpea (Di Vito and Greco 1988 ).…”

“…The nematode was able to complete two generations in both cropping seasons according to its thermal requirements (Tb = 11.4 °C and thermal constant = 500 degree days over Tb; Giné et al 2014 ).…”

“…Those parameters refer to nematode population growth but do not provide valuable information on marketable crop yield, which is provided by the relationship between Pi and relative crop yield by the Seinhorst damage function model, the tolerance limit and the minimum relative yield (Seinhorst 1965 ). It is known that plant growth and yield are reduced at increasing Pi above the tolerance limit due to a reduction of water and nutrient intakes, and consequently, a reduction of plant conductivity and transpiration, as well as leaf chlorophyll content and photosynthesis rate (Loveys and Bird 1973 ;Melakeberhan 2003 to Pi (Melakeberhan et al 1985 ;Giné et al 2014 ;López-Gómez et al 2015 ). Therefore, these ecophysiological parameters might be potential indicators of tolerance and yield losses, but it needs to be evaluated under field conditions.…”

Penetration and post-infection development of root-knot nematodes in watermelon

“…The leaf chlorophyll content (LCC) has been used as an indicator for evaluation of nematode damage (Loveys & Bird, 1973;Melakeberhan et al, 1985;Giné et al, 2014;López-Gómez et al, 2015) due to the strong correlation between LCC and the nitrogen content of the plant (Gholizadeh et al, 2009;Pôrto et al, 2011). Changes in LCC may be detected before the appearance of disease symptoms (Wagner et al, 2006).…”