Effects of Shade Nets on Microclimatic Conditions, Growth, Fruit Yield, and Quality of Eggplant (Solanum melongena L.): A Case Study in Carnarvon, Western Australia

Abstract

Carnarvon has a hot, semi-arid climate with high temperatures and solar radiation during spring–summer, which damages crops and limits the production season for the local vegetable industry. Protective cultivation is one of the promising approaches to mitigate these adverse weather conditions and avoid the resulting damage to vegetable crops. This study, which is part of the protected cropping research program for vegetable crops in Western Australia, was conducted to understand how the shade nets of a protective net house modify the microenvironment affecting the growth, physiology, and fruit yield of eggplants, a model vegetable crop. The eggplant crop was grown under four light regimes, i.e., three shade factors (11%, 21%, 30%) and the open field. There were three replicated blocks under each light regime and four eggplant varieties that were randomized within the replicated blocks. Other experimental conditions, e.g., fertilising, irrigation, pest, and disease management and other cultural practices were identical across light regimes. The results showed that shade nets created different microenvironments inside the net house, with a large variation in the light intensity, affecting photosynthetic-related traits. Eggplants grew taller and bushier and gave higher fruit yield under shade compared to the open field. Overall, our data suggest that the 21% shade net appeared to be the most suitable for growing eggplants during the autumn to early spring period in Carnarvon. The future perspective of protected cropping technology for vegetable crop production in Carnarvon is also discussed.

Mitigating the Adverse Effects of Semi-Arid Climate on Capsicum Cultivation by Using the Retractable Roof Production System

“…Using the RRPS system also allows growers some flexibility to grow in soil or soilless media. This important feature makes RRPS advantageous over the conventional net houses in semi-arid regions, which were described previously by Nguyen et al [ 4 ], where soilless growing media cannot be used due to water-permeable roofing. In locations where there are serious problems of soil-borne pathogens, the ability to apply soilless cultivation is essential.…”

“…The experiment was designed similarly to our previous experiment [ 4 ]. In brief, the experimental design was a Randomised Complete Block Design (RCBD) with three replicated blocks in each growing environment, the varieties are randomised within the replicated blocks.…”

“…However, our endeavour to increase agricultural production in general and for vegetable production, in particular, is being critically impacted by climate change [ 3 ]. In the semi-arid climatic regions, which feature high temperatures, high solar radiation in spring and summer, low annual rainfall and low relative air humidity, the weather extremes affect the growth, development and yield, as well as fruit quality of vegetables [ 4 ]. These extreme conditions will likely be exacerbated in the future by climate change.…”

“…The high light intensity plus high temperature can cause fruit burn (or sunscald) [ 11 ]. Other studies on fruiting vegetables also show that extreme sunlight can cause radiation stress on plants, critically affecting their growth and development [ 4 ]. To overcome this issue, breeders can select varieties that exhibit sufficient leaf cover that can shield the fruit from sunscald.…”

“…Our previous study showed that in a semi-arid climate, excessive sunlight was the critical factor affecting the crop growth, physiology, and fruit yield of vegetables and that it could be mitigated by using fixed-roof net houses [ 4 ]. However, this structure type is unable to cover the crops from rainfall and is prone to cyclone damage.…”