Kenneth Gravois, Keith Bischoff, T. Eugene Reagan, Jeff Hoy and Collins Kimbeng
More sugarcane varieties. That’s good news for the Louisiana sugar industry. On April 25, 2006, the LSU AgCenter released two new sugarcane varieties, L 99-226 and L 99-233, in cooperation with the U.S. Department of Agriculture’s Agriculture Research Service Sugarcane Research Laboratory in Houma and the American Sugar Cane League.
The Louisiana sugar industry has battled through some hard times in its long history, and 2005 proved no exception. After a promising start to the crop, rust disease and drought began to take their toll by mid summer. The planting season was well under way when the devastating blow of Hurricane Katrina was felt on Aug. 29, 2005. The central and eastern portions of the sugarcane growing region in Louisiana were severely damaged by hurricane and tropical storm force winds, but the far western portions of the belt were spared. Hurricane Rita changed that on Sept. 24, 2005. Wind damage and extensive flooding dealt a harsh blow to many sugarcane growers and processors.
The harvest that followed resulted in low yields. This, along with a stagnant price, cast a pall over the Louisiana sugar industry as 2005 wrapped up. But some bits of good news were on the horizon. The performance of three previously released sugarcane varieties – HoCP96-540, L 97-128 and Ho 95-988 – showed signs of promise as potential replacements for LCP 85-384. Yields of LCP 85-384 have been declining in the past few years, primarily as a result of sugarcane rust disease. Another bit of good news was the performance of L 99-226 and L 99-233.
The crosses for the two new varieties were made at the crossing facilities of the Sugar Research Station in September 1994. Photoperiod facilities were used to induce flowering in the parental clones. The parents used for the cross of L 99-226 were HoCP 89-846 and LCP 81-30. The parents of L 99-233 were CP 79-348 and HoCP 91-552. Seedlings from these crosses were planted in the field in April 1995. Early stage selection culminated in the assignment of permanent varietal designations. For these varieties, the "L" indicates that both the cross and early-stage selection occurred at the LSU AgCenter’s Sugar Research Station, the "99" indicates the year (1999) of assignment; and the numbers – 226 and 233 – are from a consecutive set of numbers between 1 and 499 used by the AgCenter’s sugarcane breeding program for unique variety identification.
The next stages of the sugarcane breeding program are variety testing. These stages include on-station nurseries, off-station nurseries and infield variety trials, and the final stage, referred to as outfield variety trials. Data from variety testing include measures of sugar yield (pounds of sugar produced per acre of land), cane yield (tons of sugarcane produced per acre of land) and sucrose content (the pounds of sugar produced per ton of sugarcane). At the same time experimental clones are introduced to the outfield variety trials, they are provided to the American Sugar Cane League for "seed" increase. This isn’t actual seed but whole stalks because sugarcane isn’t grown from seed. Stalks from a plant are cut and planted, and the buds along the stalks germinate and grow to produce new plants. This increase through cutting and planting of stalks, or "seedcane," is a process known as vegetative propagation. The American Sugar Cane League provides seed to any sugarcane grower requesting an allotment. For L 99-226 and L 99-233, seed will be made available to growers in late summer of 2006.
New sugarcane varieties are eagerly anticipated to replace LCP 85-384, which in 2005, was planted on 89 percent of the Louisiana’s sugarcane acreage. New varieties with comparable yield potential are important to avoid risks associated with monocultures – growing extensive acreage of a single variety. L 99-226 and L 99-233 should provide growers with viable choices when selecting alternative varieties to plant.
The main criterion that growers use when selecting varieties to plant is yield. To the sugarcane grower, sugar yield, cane yield and sugar per ton of cane are the main traits of interest. Information from the outfield variety trials is reported in Table 1. Information is provided for plant-cane, first stubble (ratoon) and second stubble crops.
L 99-226 had the highest sugar yield and sugar per ton of cane of any variety reported. This new variety also had the highest cane yield in the plant-cane and first stubble crops. The variety is charac terized as having a moderate population of large-diameter stalks.
L 99-233 produced significantly higher sugar and cane yields than LCP 85-384. Its sugar per ton of cane is similar to LCP 85-384. This new variety is characterized as having a high population of small diameter stalks. L 99-233’s high cane yield in second stubble is an indication that the variety is an excellent stubbling variety.
Harvesting characteristics are important for sugarcane varieties. Both new varieties tend to lodge (or fall over), with L 99-233 lodging more severely than L 99-226. Because of their propensity to lodge and their high cane yield, these varieties are better suited to combine harvesting systems, which more easily pick up leaning plants.
Disease resistance is another important component of variety selection. L 99-226 and L 99-233 are moderately resistant to smut, moderately resistant to brown rust and moderately resistant to leaf scald under natural field infection. Both varieties are also moderately resistant to Sorghum mosaic virus. The effect of yellow leaf disease on the yield of both L 99-226 and L 99-233 is unknown. These new varieties may sustain significant yield loss in stubble crops from ratoon stunting disease. To realize the maximum yield potential of these varieties, healthy seed cane, free of ratoon stunting disease, must be planted.
Resistance to the sugarcane borer is a key aspect necessary for reducing the number of insecticide applications. L 99-226 is resistant to the sugarcane borer. A new sugarcane variety with resistance to the sugarcane borer is badly needed in the Louisiana sugar industry. Growers have limited options. The majority of acreage in Louisiana is planted to susceptible varieties. L 99-226 is a good choice for planting in areas near neighborhoods, schools and hospitals where insecticides should not be used for control of the sugarcane borer. L 99-233 is susceptible to the sugarcane borer and should be scouted for timely insecticide applications.
Louisiana’s sugar industry has continually looked toward the public sector for the development of new varieties. The arrival of new sugarcane varieties is a highly anticipated event. L 99-226 and L 99-233 should pay big dividends in the future for Louisiana’s growers and processors. (This article was published in the summer 2006 issue of Louisiana Agriculture.)