Population dynamics of Meloidogyne javanica and its relationship with the leaf chlorophyll content in zucchini

Abstract

Root-knot nematodes (RKN), Meloidogyne spp., are major limiting factors for vegetable production worldwide (Sikora and Fernandez, 2005). Management of nematode problems in RKN conductive systems, such as protected cultivation in plastic greenhouses, is a major challenge since crop intensity and environmental conditions under the plastic cover favor pest and disease development. Crops with long and short cycles are cultivated generally in rotation with solanaceous (tomato, pepper and eggplants) and cucurbitaceous (cucumber, melon, watermelon, and zucchini) crops with short fallowing periods (4--8 weeks) between successive crops (Sorribas and Verdejo-Lucas, 1994;Talavera et al., 2012).The European Directive 2009/128/EC on the sustainable use of plant protection products promotes integrated production as a means for reducing pesticide use. To achieve this goal, it is necessary to understand the host--parasite relationship in the rotational crops of the production system for estimating nematode damage thresholds, predicting yield losses and modelling modeling the population dynamics. The damage potential of the nematode to the crop has been described by mathematical models (Seinhorst, 1965). Estimation of the potential growth of the RKN population will provide information on the suitability of the crop and tolerance to the nematode. A negative relationship between the initial population density (Pi) and the reproduction rate (Pf/Pi), Pf being the nematode population density at harvest, has been described in several susceptible annual crops (Ferris et al., 1986). Damage caused by RKN is determined by relating Pi to growth and yield. The minimal density that causes a measurable reduction in plant growth or yield varies with nematode species, host plants, cultivar and environment (Barker and Olthof, 1976). It is generally accepted that cucurbitaceous crops are susceptible to RKN but differences in susceptibility levels have been observed (López-Gómez and Verdejo-Lucas, 2014). Yield losses have been reported in cucumber and melon (Ornat et al., 1997;Ploeg and Phillips, 2001;Kim and Ferris, 2002;Giné et al., 2014).However, few studies have focused on the development of damage-functions models for zucchini, Cucurbita pepo L. (Ferris et al., 1986;Vela et al., 2014).As obligate sedentary endoparasites, RKN interfere with plant physiological processes involved in water uptake and nutrient translocation and create an imbalance of macro and micro-nutrients; in consequence, leaf chlorosis and stunted Population dynamics of AbstractThe relationship between the initial (Pi) and final (Pf) population densities of Meloidogyne javanica in response to increasing initial inoculum levels and the effect on yield in zucchini cv. Amalthee (Cucurbita pepo L.) was determined using a geometric series of 12 Pi from 0 to 51,200 eggs/100 cm 3 of soil in pot experiments in a greenhouse. The maximum multiplication rate was 425, and the equilibrium density was 701,951 eggs/100 cm 3 soil. The relative yield, represented as dry top weight, fit t...

Comparison of Proximal Remote Sensing Devices for Estimating Physiological Responses of Eggplants to Root-Knot Nematodes

“…Therefore, the only significant differences reported were in growth. In fact, in previous studies changes in yield of grafted and ungrafted cucumber were related to the relative variation in both chlorophyll refelctance and net photosynthetic rate [16], confirming previous results in which relative dry top weight of cucumber [17] or zucchini-squash biomass [18] was related to relative leaf chlorophyll content measured earlier in the plant-nematode interaction and in situations in which root-knot nematode was the main agent of biotic stress. Alternatively, the effect of nematodes in the plant status was mild but accumulative.…”

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

“…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. These results suggest that reflectance based chlorophyll indices might provide an estimation of the effects of Pi on photosynthetic capacity and their effects, thereof, on yield in situations in which RKN is the main biotic stressful agent.…”

“…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.…”

Pathogenicity of Meloidogyne incognita and M. javanica on recombinant inbred lines from a crossing of Cucurbita pepo subsp. pepo × C. pepo subsp. ovifera

“…Females reaching the egg‐laying stage showed reduced fecundity. This resistance has proven effective against several M. incognita isolates on a range of zucchini genotypes (López‐Gómez et al ., 2015b; Verdejo‐Lucas & Talavera, ). Intermediate resistance can be useful to regulate population increases, particularly in non‐chemical sustainable agriculture, because the genetic background of the plant may provide tolerance to nematode damage due to superior vigour, an extensive root system or tolerance to environmental stresses.…”