Inheritance of Sugarcane Ratooning Ability and the Relationship of Younger Crop Traits to Older Crop Traits

Abstract

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

Simultaneous selection for yield and ratooning ability in sugarcane genotypes using analysis of covariance

“…Previous studies by Milligan et al (1996) defined ratooning ability as the ratio of second ratoon to plant crop yield and is widely used by sugarcane breeders. Using this data set, an analysis of variance of the ratio of second ratoon to plant crop produced non-significant genotype effects for both sugar yield (P = 0.1622) and stalk population (P = 0.5398), indicating that genotypes had similar ratooning ability.…”

“…Although growers may not evaluate such scenarios at the farm, researchers can present possible options from such studies to provide guidance to growers on variety choice. The ratooning index of Milligan et al (1996) used point estimates ignoring the effect of ratooning cycles. Figures 1 and 2 indicate that the effect of ratooning cycles is important.…”

“…Genotype 93-2317 produced a total of 670 700 stalks ha -1 and 14% more stalks than N14 (587 490 stalks ha -1 ). This analysis would not be possible using the approach described by Milligan et al (1996).…”

“…Statistical methods that provide tests to compare genotypes for yield and ratooning to a control across ratooning cycles would enhance selection for ratooning ability. Previous studies (Milligan et al 1996) compared genotypes using point estimates and thus did not cater for the yield decline that occurs across the ratooning cycles. In the present study, the analysis of covariance method is not used in its strictest form but rather to generate the parameters, for example slopes, that can then be used to describe and compare genotypes for yield and ratooning ability.…”

Analysis of multienvironment trials (MET) in the sugarcane breeding program of Réunion Island

“…They have been quantified for cane yield and sucrose content or for derived sucrose yield in breeding programs at various locations, including Australia (Jackson and Hogarth 1992;Mirzawan et al 1994), Florida (Milligan et al 1996;Glaz and Kang 2008), South Africa (Parfitt 2000;Ramburan et al 2012a), Venezuela (Rea and De Souza Vieira 2002), and Argentina (Mariotti and Clariana 1994). All these examples of MET studies encompassed locations spread over relatively large cultivated areas, necessarily made up of environments that are more or less heterogeneous in various regards, such as soil type (Milligan et al 1996;Glaz and Kang 2008) or cultivation practices (Mirzawan et al 1994). Studies providing formal statistical tests of interactions revealed that both GL and GC effects were always significant for all traits surveyed, except on one occasion (Parfitt 2000).…”