Two long term productivity trials were established at the DAF Gatton research Facility over the course of this project. The trials investigated the value of rootstocks, varieties, ratooning and shading. A formal literature review of plant material, production techniques and technological advances in capsicum and chilli was undertaken as a first step in determining the project work program.

In trial number one at Gatton, all five graft treatments were based on the commercial variety Warlock as the scion. The rootstock treatments evaluated were; Warlock self-grafted (to evaluate grafting impact), non-grafted Warlock, a commercial chilli line Caysan known for its resilience under a range of conditions, a newly released commercial capsicum rootstock Capsifort and Wild Malay Eggplant (WME).

Three other varieties, a new variety SV6947 and two older heirloom lines were included in planting 1. The new Monsanto variety SV6947 produced the highest total marketable yield – though this yield was only significantly higher than the chilli graft (Caysan) and the two older varieties, Yolo Wonder and Green Giant. The new variety SV6947 displayed a beneficial, more uniform flowering and fruit position pattern within the plant.

Following harvest, all plants were cut back by hand (May 2014) and ratoon crop regrowth was assessed. Regrowth was equal across all treatments however the cold weather resulted in both small plant and fruit size. Marketable yield of the May ratooned crop was poor. Timing was the issue the ratooning treatment should have been delayed until mid-July, allowing the ratoon crop to grow into the warm spring.

Root health of all graft and variety treatments was assessed 482 days after initial planting. Analysis of root dry weight revealed that new crop Warlock had the healthiest root system, while grafted Warlock had a healthier root system than the commercial rootstock and new variety SV6947. Standard Warlock and grafted chilli had a similar root health rating to grafted Warlock.

The chilli graft reduced canopy height and increased density but did not reduce fruit sunburn. Sunburn is a major cause of marketable fruit and income loss. Crop 3 grown through the November 2014 period had a mean fruit sunburn incidence of 34%. Local commercial growers experienced severe production losses with 40 to 60% of marketable yield lost to sunburn in the November / December harvest period of 2014.

Trial number 2 at Gatton in October 2015 evaluated 3 different graft combinations, one older variety and another new capsicum variety. Crop 5 data showed Plato, new line SV9699, SV6947 (scion) grafted to Warlock and Warlock grafted to Hungarian Hot Wax to be the highest yielding treatments. This crop was mechanically cut back in February 2016 and a sixth crop harvested in May 2016. Planting 2 was grown under a cheap prototype protective net cover. This reduced summer sunburn levels from the 34% in crop 3 to around 4% in crop 5.

Fruit quality under the protective net was exceptional with one local capsicum grower who visited the trial area commenting that fruit being harvested was similar to glass house quality. This was a result of slightly increased humidity in a hot dry growing environment and an average temperature reduction of 4oC between 1 and 3 pm recorded under the protective net. Capsicum fruit harvested from under the net were shiny with smooth skin and looked as though they had been polished.