Biofumigation effects of brassicaceous cover crops on soil health in cucurbit agroecosystems in Hawaii, USA
Section snippets
INTRODUCTION
Biofumigation is an agronomic practice that utilizes isothiocyanates (ITCs) generated from the breakdown of glucosinolates (GLs) present in brassicaceous crops to manage soil-borne pests and pathogens in agroecosystems (Kirkegaard et al., 1993). Glucosinolates are stored in the vacuoles of brassicaceous plant cells. Upon tissue maceration, GLs get in contact with the endogenous enzyme myrosinase in the cell wall or cytoplasm and undergo hydrolysis to release glucose and aglycone moieties.
Trial I
A field trial was initiated on November 17, 2016, at the Poamoho Experiment Station, Waialua, Hawaii, USA (21°32′14.7″ N, 158°5′20.2″ W; 166–215 m above sea level). The soil at the experimental site was a well-drained silty clay Oxisol (Wahiawa series, very fine, kaolinitic, isohyperthermic, Rhodic Haplustox), with a pH of 6–7 and organic matter content of 9 g kg-1. The soil was naturally infested with reniform (Rotylenchulus reniformis) and root-knot (Meloidogyne incognita and Meloidogyne
RESULTS
The nematode genera present in all three field trials are presented in Table I, and the abundance of each nematode genus in every trial is presented in Tables SI–SVI (see Supplementary Material for Tables SI–SVI).
Effects of oil radish and brown mustard biofumigation on nematode communities
Based on the nematode community analysis, oil radish was better for soil health improvement than brown mustard especially when it was terminated by MTBP. This termination method suppressed plant-parasitic nematodes, increased nematode diversity and bacterivore abundance, and reduced the F/(F + B) ratio and CI, indicating higher bacterial decomposition than fungal decomposition in the soil. In addition, oil radish terminated by MTBP increased EI, indicative of soil nutrient enrichment. All of
CONCLUSIONS
This study demonstrated that biofumigation can be effective against plant-parasitic nematodes without compromising soil health or changing the nematode community structure. Oil radish or brown mustard as a biofumigant crop, if terminated by the MTBP method for one week, suppressed the abundance of plant-parasitic nematodes. Bacterial decomposition was enhanced in the MTBP treatment, which led to nutrient enrichment. However, sometimes these effects did not last throughout the subsequent
ACKNOWLEDGEMENTS
This work was funded in part by the University of Hawaii College of Tropical Agriculture and Human Resources (Nos. 9034R, 9048H, and POW 16-964), the Natural Resources Conservation Services-Conservation Innovation Grants (Nos. NR 1892510002G004 and 69-9251-15-957), and the Western Sustainable Agriculture Research and Education Graduate Student Grant (No. GW18-026) of USA. The authors thank Ms. Donna Meyer, Mr. Josiah Marquez, Ms. Shelby Ching, Ms. Shova Mishra, and Dr. Xiaodong You for their
References (44)
- et al.
Functional diversity of nematodes
Appl Soil Ecol
(1998) - et al.
A framework for soil food web diagnostics: Extension of the nematode faunal analysis concept
Appl Soil Ecol
(2001) - et al.
Brassicacea-based management strategies as an alternative to combat nematode pests: A synopsis
Crop Prot
(2016) - et al.
Assessing nematode communities in agroecosystems of varying human intervention
Agric Ecosyst Environ
(1993) - et al.
Glucosinolate and isothiocyanate concentration in soil following incorporation of Brassica biofumigants
Soil Biol Biochem
(2006) - et al.
Brassicaceous and rye cover crops altered free-living soil nematode community composition
Appl Soil Ecol
(2010) - et al.
Isothiocyanate release from soil-incorporated Brassica tissues
Soil Biol Biochem
(2002) - et al.
Using the concentration-dependence of respiration arising from glucose addition to estimate in situ concentrations of labile carbon in grassland soil
Soil Biol Biochem
(2014) - et al.
Effects of yellow mustard amendments on the soil nematode community in a potato field with focus on Globodera rostochiensis
Appl Soil Ecol
(2012) - et al.
Release of isothiocyanates does not explain the effects of biofumigation with Indian mustard cultivars on nematode assemblages
Soil Biol Biochem
(2014)