Growth and physiological changes in continuously cropped eggplant (Solanum melongena L.) upon relay intercropping with garlic (Allium sativum L.).

Mengyi Wang,Cuinan Wu,Zhihui Cheng,Huanwen Meng

doi:10.3389/fpls.2015.00262

Mengyi Wang, Cuinan Wu + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2015.00262

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Abstract

Relay intercropping represents an alternative for sustainable production of vegetables, but the changes of internally antioxidant defense combined with the growth and yield are not clear. Field experiment was carried out to investigate the malondialdehyde (MDA) content and activity levels of superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) in eggplant (Solanum melongena L.) and plant height, stem diameter, maximal leaf area, and yield of eggplant grown under successive cropping in the year 2011 and 2012 to see if relay intercropping with garlic (Allium sativum L.) could benefit to eggplant growth and yield. Three experimental treatments with three repeats in each were carried out (completely randomized block design): eggplant monoculture (CK), eggplant relay intercropping with normal garlic (NG), and eggplant relay intercropping with green garlic (GG). In both years, the MDA content was significantly lower and SOD and POD activities were generally lower in NG and GG compared with CK in most sampling dates. PPO activity trends were generally opposite to those of POD. The general trend of PAL activity was similar to MDA. The plant height and stem of eggplant was lower, but the maximal leaf area was larger in NG and GG in 2011; in 2012 the plant growth was stronger in relay intercropping treatments. For eggplant yield in 2011, NG was 2.85% higher than CK; after the time for the green garlic pulled out was moved forward in 2012, the yield was increased by 6.26 and 7.80%, respectively, in NG and GG. The lower MDA content and enzyme activities in relay intercropping treatments showed that the eggplant suffered less damage from environment and continuous cropping obstacles, which promoted healthier plant. Thus from both the growth and physiological perspective, it was concluded that eggplant/garlic relay intercropping is a beneficial cultivation practice maintaining stronger plant growth and higher yield.

Highlights

Continuous cropping is a simple, repetitive agronomic practice that is often performed for vegetables cultivated under protection in China due to concerns of land-use efficiency and the cultivation habits of farmers (Xiao et al, 2012)
The lower Superoxide dismutase (SOD) activity in the eggplant relay intercropping with normal garlic (NG) and eggplant relay intercropping with green garlic (GG) treatments indicates that relay intercropping with normal garlic or green garlic could offer better protection for eggplant plants compared with monoculture-grown plants
The MDA content in the GG treatment was lower than that in the NG treatment for most sampling dates, with the exception of July 25, 2011. These results indicate that eggplant under relay intercropping with normal garlic or green garlic suffered less damage from environment or continuous cropping obstacles than monocropped eggplant

Summary

Introduction

Continuous cropping is a simple, repetitive agronomic practice that is often performed for vegetables cultivated under protection in China due to concerns of land-use efficiency and the cultivation habits of farmers (Xiao et al, 2012). The continuous cropping of eggplant, which commonly occurs in China, can have negative effects, including increase in autotoxins in the plant which blocks its growth; decrease in resistance to bad environment; slow development; and reduce in yield and quality. As crop rotation rarely occurs in protected plastic tunnel systems because of the limited land area available under the plastic tunnels and Chinese farmers are accustomed to repeatedly planting the same crop in the same field, the cultivation pattern of relay intercropping has recently garnered increasing attention. Another study found that tomato plants intercropped with marigold or pigweed grew longer stems (26–33%) and thinner leaves (33–35%) than plants grown alone (Gómez-Rodríguez et al, 2007)

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