Thomas L. Tew

Planting Method and Timing Effects on Sugarcane Yield

Sugarcane (Saccharum spp.) in Louisiana is propagated from vegetative plantings in late summer and early fall as either whole stalks with 4 to 8 nodal buds or as stalk pieces (billets) with 2 to 4 buds. This research was conducted to determine if planting method and planting date affects yields of the varieties currently grown in Louisiana. Billet planting was compared to whole-stalk planting at three planting dates (August 15, September 15, and October 15) for 2 years with three different varieties (LCP 85-384, HoCP 85-845, and HoCP 95-555). Cane and sugar yields were compared in plant-cane and first-ratoon production years. When compared to whole-stalk planting, cane and sugar yields from billet planting were inconsistent, and no clear trends were observed. Averaged across varieties and planting method, the August planting date had higher cane and sugar yields than the September and October plantings. All varieties responded similarly to billet and whole-stalk planting. Our data suggest that farmers should attempt to plant the majority of their crop in August to maximize yields and should be aware that billet planting may give inconsistent yields compared with whole-stalk planting.

Microsatellite DNA marker-assisted selection ofSaccharum spontaneum cytoplasm-derived germplasm

New lines of Saccharum hybrids with an array of S. spontaneum cytoplasm backgrounds are reported. To expand the genetic base of sugarcane, we made eleven bi-parental crosses between ten S. spontaneum (S) and six commercial-type sugarcane (C) clones during the 2001 crossing season. Prior to crossing, all the maternal S. spontaneum inflorescences were emasculated by immersion in a 50°C circulating water bath for 5 minutes. Analysis of microsatellite fingerprints between parents and progeny allowed us to classify 1,952 progeny grown out from these crosses into four genotypic classes. Class H progeny inherited microsatellite alleles from both the S. spontaneum and the commercial-type parents and were, therefore, considered being F1 hybrids. Class S and Class C progeny inherited microsatellite alleles only from one parent and were considered to be either selfs of either parent or F1 hybrids that only inherited allele(s) from one parent. Class X progeny inherited non-parental microsatellite allele(s) in addition to the allele(s) from the maternal S. spontaneum parent and were considered to be contaminants. With the exception of one cross, eight to ten Class H progeny were pre-selected from each cross while still in seedling greenhouse and were backcrossed with commercial-type sugarcane clones. The remaining progeny were transplanted into a breeding nursery for phenotypic evaluation that concurred with the molecular classification. Pearson Correlation Coefficients between molecular and phenotypic classifications were inconsistent that justified the need of molecular markers in the selection process. This study demonstrated that the molecular approach of fingerprinting progeny to confirm parentage prior to field planting even with only one microsatellite marker might substantially increase selection efficiency.

Biomass production of herbaceous energy crops in the United States: field trial results and yield potential maps from the multiyear regional feedstock partnership

Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small‐scale and short‐term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long‐term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field‐scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm‐scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM‐ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country.

Comparison of biparental and melting pot methods of crossing sugarcane in Hawaii

Sugarcane (Saccharum hybrid spp.) breeders at the Hawaiian Sugar Planters’ Association used biparental and melting pot (modified polycross) crossing methods concurrently from 1935 to 1985. While the annual effort expended to make biparental crosses exceeded the effort to make melting pot crosses over this 50-year period, annual viable seed yield from biparental crosses was usually less than 15% of that from melting pot crosses and hence, the numbers of seedlings planted to the field from those crosses usually accounted for less than 20% of the total seedling population. In 1985, nine of the 10 sugarcane cultivars listed in Hawaii’s variety census originated from melting pot crosses; only one originated from a biparental cross. In the face of a shrinking sugar industry in Hawaii and a smaller work force in the breeding program, the decision was made in 1985 to rely primarily on melting pot crosses for the production of commercial cultivars. From 1985 to 2005, twelve additional clones that were bred prior to 1985 eventually attained “commercial cultivar” status by exceeding 1% of the total cane growing area. All twelve originated from melting pot crosses. Over the 50-year period that the two crossing methods were used, the melting pot method proved to be more labour efficient and ultimately contributed more than the biparental crossing procedure toward the development of new commercial cultivars for the Hawaiian sugar industry. From 1985 forward, the biparental crossing method was used more for introgressing desired traits from exotic germplasm than for the development of commercial cultivars.