INHERITANCE OF SUGARCANE RATOONING ABILITY AND THE RELATIONSHIP OF YOUNGER CROP TRAITS TO OLDER CROP TRAITS

The inheritance of ratooning ability and the relationship of traits am ong crops in sugarcane (Saccharum spp. hyb.) has not been well examine d. Ratooning ability (RA) was defined as the second ratoon (SR) crop y ield percent of the plant cane yield. A replicated 4-yr test at four l ocations of 37 genotypes was studied for two three-crop cycles. Broad- sense single-plot heritabilities for RA were low (H less than or equal to 17%), while the genetic coefficient of variation of RA was largest for sucrose yield and cane yield (GCV approximate to 14.5%), and smal lest for stalk diameter (GCV = 1.5%). Cane and sucrose yield RA demons trated the largest potential for gain, while stalk weight, stalk diame ter, and stalk length showed the least. Except for sucrose and cane yi eld and stalk number, other traits were highly correlated between plan t cane and SR crops (r greater than or equal to 0.78). Stalk number in the younger crop was the only trait significantly correlated to ratoo n crop cane yield (r = 0.56), suggesting that selection for stalk numb er in the younger crops would enhance older crop yields. The results i ndicate that SR crop yields could be predicted by first ratoon crop yi elds. However, the best improvement of SR yields would be realized by selection in the SR.