Lignocellulosic composition not associated with stem borer resistance in select Louisiana sugarcane cultivars

Authors: Penn, Hannah; Johnson, Richard; Richard, Katie; Richard, Randy; WHITE, WILLIAM - Retired ARS Employee

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2023
Publication Date: 11/3/2023
Citation: Penn, H., Johnson, R.M., Richard, K.A., Richard, R.T., White, W.H. 2023. Lignocellulosic composition not associated with stem borer resistance in select Louisiana sugarcane cultivars. Agronomy. 13(11).Article 10.3390. https://doi.org/10.3390/agronomy13112764.
DOI: https://doi.org/10.3390/agronomy13112764

Interpretive Summary: Sugarcane in Louisiana has two main pests – the sugarcane borer and the Mexican rice borer– that will tunnel into plant stalks and decrease the sugar levels in the plant. One way to stop these pests without using chemicals is by planting varieties of sugar cane that are less likely to be targeted by pests. Sugarcane varieties with high fiber levels are less attractive to pests, because fiber makes the plant harder for the pests to chew and eat. Unfortunately, high fiber plants also make it harder for sugar mills to get the sugar out of the plant. The total fiber in a plant is made up of a few different types of fiber, and some of these types may still stop pests without making it hard to get the sugar. In this study, we wanted to find out if certain types of fiber stop the pests. To do this, we looked at three types of fiber, the total fiber, and the total sugar in four different varieties of sugarcane that have different pest risks. We found that sugarcane varieties with lots of pests had higher sugar levels. The sugarcane varieties with less pests had high total fiber, but the individual types of fiber did not matter. This means that types of fiber should not be the focus when choosing varieties of sugarcane to stop pests.

Technical Abstract: The two most economically damaging insect pests of sugarcane in Louisiana are the sugarcane borer (SCB) and the newly invasive Mexican rice borer (MRB), both of which can be managed in part with cultivar resistance. High stalk fiber is a well-documented aspect of stem borer resistance but is inversely correlated with recoverable sugar levels. However, lignocellulosic components such as hemicellulose, cellulose, and lignin are associated with resistance to other borer species in poaceous crops, potentially indicating mechanisms that may provide resistance without substantial trade-offs in yield. The goal of this study was to determine if lignocellulosic composition varied among four cultivars - HoCP 85-845, HoCP 04-838, Ho 07-613, and HoCP 00-950 – that were selected based on known variation in SCB and MRB resistance and total fiber content. We estimated lignocellulosic composition as well as Brix throughout the growing season and the total stalk fiber and recoverable sugar content at harvest for both plant cane and first ratoon crop years. We found that Brix content throughout the growing season, as well as total fiber and sugar content at harvest, were significantly associated with cultivar, aligning with previously documented trends in borer resistance (i.e., higher brix and lower total fiber indicated a more susceptible cultivar). While lignocellulosic composition during the growing season was not associated with cultivar or resistance to either borer species, it was significantly impacted by sampling month and crop year. These data indicate the potential influence of alternative resistance mechanisms and interactions with abiotic conditions.