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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.

‘L 79‐1002’ (Reg. No. CV‐132, PI 651501) sugarcane (a complex hybrid of Saccharum officinarum L., S. spontaneum L., S. barberi Jeswiet, and S. sinense Roxb. amend. Jeswiet) was released on 26 Apr. 2007 by the Louisiana State University Agricultural Center in cooperation with the USDA‐ARS and the American Sugarcane League, Inc. The cross for L 79‐1002, a F1 hybrid, was made in 1974 using ‘CP 52‐68’ as the female parent and Tainan, a S. spontaneum clone, as the male parent. Initial clonal selection was done in single stools. Testing was done from 1976 through 1983 in yield trials conducted in the traditional sugarcane growing area in south Louisiana and in the colder, non‐sugarcane growing regions of north Louisiana. Yield testing was resumed in 2002 through 2005 as interest in biofuels research renewed. L 79‐1002 was released for an emerging biofuels industry because of its high fiber content and biomass (cane yield) potential. Average fiber content for L 79‐1002 is approximately 257 g kg−1 The new cultivar also has excellent vigor and ratooning ability. Experiments conducted at Bossier City, Louisiana (32.1° N lat) indicated a broader range of adaptability than sugarcane cultivars grown for the production of sucrose.

Without an adequate and uniform rice (Oryza sativa L.) stand, optimum rough rice yields are difficult to attain. Most seeding rate research has emphasized optimizing rough rice yields, with little consideration given to the effect of seeding rate on head rice (percentage of whole milled kernels) and total milled rice (percentage of whole milled kernels plus milled broken kernels). Thus, our objective was to assess the effect of seeding rate on head rice and total milled rice of two very early‐season rice cultivars (Millie and Adair) and two midseason rice cultivars (Katy and Kaybonnet). The experiment was conducted at the Pine Tree Experiment Station near Colt, AR, during 1992 and 1993. The cultivar (maturity group) × seeding rate interaction was significant for head rice and total milled rice, suggesting that, for head rice and total milled rice, the four cultivars responded differently to seeding rate. There was a linear decrease in head rice as seeding rate decreased for Millie, a quadratic decrease in head rice as seeding rate decreased for Adair, and a linear increase in head rice as seeding rate decreased for both Katy and Kaybonnet. We surmise that increased tillering and decreased kernel weights at the lower seeding rates decreased the head rice for Adair and Millie. Total milled rice decreased linearly with decreasing seeding rate only for Adair. When evaluating thin rice stands for potential performance or replanting, both cultivar and head rice and total milled rice losses should be considered.

Estimates of genetic variances and derived statistics of pertinent traits are essential for efficient plant breeding programs. For clonal sugarcane (Saccharum spp.) populations in Louisiana, such estimates (and unconfoanded estimates of genotype by environment [GE] and genotype by crop [GC] variances) were lacking. The objectives of this study were to estimate broad‐sense genetic and GE variance components for a clonal sugarcane population representative of initial stages of replicated testing and to determine the relative importance of years, locations, and crops. Thirty‐seven genotypes were planted in 1983 and replanted in 1984 in replicated tests at five locations. Data from two 3‐yr. crop cycles were used. Genetic advance (GA) indicated considerable improvement potential in sucrose yield, cane yield, and stalk number and weight. Genotypic variance was generally secondary to error variance in determining phenotypic variance; GE variances were tertiary to genotypic and error variances. Within a crop, genotype by location (GL) variances tended to be larger than genotype by year (GY). Estimates of potential of plant cane sucrose yields over years and locations implied testing across locations could substitute for years, effectively reducing the time to identify elite clones. Analysis across crops showed GC, GL and GYL interaction variances were usually larger than GY. Estimates of GA showed no difference in potential gain from replicating across years vs. crops. For several traits, the most potential for improvement is in older crop performance, and selection is best practiced with regard to crop.

Genetic correlations provide useful information to plant breeders for developing selection schemes. Genetic correlations among yield and yield components (panicle number, panicle weight, panicle length, primary branches, and plant height) for U.S. southern long‐grain rice (Oryza sativa L.) have not been reported. The objectives of this work were to estimate and use genetic correlations in developing selection methodologies in rice breeding programs. In 1989, two 4 × 4 crossing factorials (Design II) were completed, and the 32 F1 hybrids and the 16 parents were evaluated in 1990 at two Arkansas locations (Stuttgart and Marianna). Additive genetic and broad‐sense genetic correlations were estimated. At both the additive and broad‐sense genetic levels, yield was positively correlated with panicle weight. Yield was negatively correlated with panicle number, but the effect was diminished at the broad‐sense genetic level. Panicle weight was negatively correlated with panicle number. Path analysis, however, revealed positive direct effects for both panicle number and panicle weight on rice yield at both the additive genetic and broad‐sense genetic levels, with panicle weight exhibiting larger direct effects on yield than panicle number. Selection indices were developed from the additive genetic and phenotypic variances and covariances. The selection indices indicated that selecting for increased yield via selection for either panicle weight or panicle number alone would be ineffective. A selection index that included selection for both increased panicle weight and panicle number to increase yield was estimated to be 91% as effective as selecting for yield directly.

The inheritance of ratooning ability and the relationship of traits among crops in sugarcane (Saccharum spp. hyb.) has not been well examined. Ratooning ability (RA) was defined as the second ratoon (SR) crop yield percent of the plant cane yield. A replicated 4-yr test at four locations of 37 genotypes was studied for two three-crop cycles. Broad-sense single-plot heritabilities for RA were low (H _< 17%), while the genetic coefficient of variation of RA was largest for sucrose yield and cane yield (GCV = 14.5%), and smallest for stalk diameter (GCV = 1.5%). Cane and sucrose yield RA demonstrated the largest potential for gain, while stalk weight, stalk diameter, and stalk length showed the least. Except for sucrose and cane yield and stalk number, other traits were highly correlated between plant cane and SR crops (r >_ 0.78). Stalk number in the younger crop was the only trait significantly correlated to ratoon crop cane yield (r = 0.56), suggesting that selection for stalk number in the younger crops would enhance older crop yields. The results indicate that SR crop yields could be predicted by first ratoon crop yields. However, the best improvement of SR yields would be realized by selection in the SR. p~ LANTING OPERATIONS and seed (stalks for vegetative propagation) costs constitute the largest input of sugarcane production (Salassi and Giesler, 1995). Inadequate ratoon crop yields limit the economic production of sugarcane in semi-tropical regions such as Louisiana, where ratoon crop yields typically decrease with age (Johnson et al., 1993; Ricaud and Arceneaux, 1986; Shrivastava et al., 1992). The reasons for this decline are complex, but primarily relate to diseases, insects, weed competition, management practices, and winter kill (Shrivastava et al., 1992). Additionally, genotypes can vary substantially in their ratoon crop yields (Chapman, 1988; Chapman et al., 1992; Ricaud and Arceneaux, 1986; Tripathi et al., 1982). Ratooning ability can be enhanced by indirect selection for disease or insect resistance, or by direct selection of genotypes with high ratoon crop yields. Traits such as high stalk number, bud viability, vigorous root formation, high biomass accumulation, and high light use efficiency have been suggested as being indicative of better ratooning cultivars (Sundara, 1989; Ferraris et al., 1993). The importance of maintaining stalk weight in older crops has also been noted (Chapman, 1988; Chapman et al., 1992). Ratooning ability can be defined in either absolute or relative terms. In absolute terms, a good ratooning cultivar is one that produces high ratoon crop yields or several profitable ratoon crops. Relative to other cultivars, a

Sugarcane (Saccharum spp.) fiber, the dry, water‐insoluble component of the stalk, is an important quality component because of its inverse relationship to juice extraction and milling efficiency. Sugarcane cultivars in temperate regions are enhanced with S. spontaneum L. germplasm to provide increased vigor and cold tolerance. Unfortunately, S. spontaneum L. clones typically have low recoverable sucrose and high fiber content. Our objective was to estimate genetic and genotype × environment (G × E) interaction variances for sugarcane fiber content, not previously reported for a temperate sugarcane population. Twenty‐two clones from the first replicated testing stage of the Louisiana Sugarcane Variety Development Program (LSVDP) were studied in a first and second ratoon crop at three locations. Genotype × crop (G × C), genotype × location (G × L), and genotype × crop × location (G × C × L) variances were much smaller than genetic and error variances. Heritability of fiber on a single‐plot basis was 0.71 and 0.91 when heritability was based on three locations, two replicates, and one crop. From path analysis, the direct effect of fiber content on recoverable sucrose was −0.203, indicating a weak inverse relationship between these two traits. Fiber content was significantly correlated with stalk diameter, rg = −0.585, indicating that indirect selection for larger stalk diameter should decrease fiber content. Direct selection for optimum fiber content by evaluating clones in a single crop and/or location would be effective. Evaluation at different locations and during different crops, however, would offset the relatively large error variance, thereby increasing the statistical power to determine differences among clones for fiber.