Principles of seed science and technology I Lawrence O. Copeland and Miller B. McDona1d.-3rd ed. p. cm. Includes bibliographical references and index.

p. cm. lncludes bibliographical references.

ported that moisture content represents an accurate indicator of PM for soybean. Formation of a black layer The ability to identify physiological (PM) and harvest maturity at the base of kernels (Daynard and Duncan, 1969; (HM) of canola (Brassica napus L.) by phenological characteristics Carter and Poneleit, 1973) and/or progression of the would permit timely harvest to avoid problems of both under-and overripe pods. This study was conducted to identify PM and HM milk line (Afuakwa and Crookston, 1984) have been of six winter and spring canola cultivars using morphological and suggested as reliable indicators of PM in corn (Zea mays physiological markers including seed and pod color, seed dry weight L.). Black layer formation in the placental area of the (DWT), seed moisture content (SMC), and to measure seed quality seed was reported to be a good indicator of PM in (germination and vigor) at PM and HM. Pods and seeds from each sorghum [Sorghum bicolor (L.) Moench] (Eastin et al., cultivar were sampled at weekly intervals from pod formation until 1973). Because quick field estimation of PM from physi-HM. Standard germination, accelerated aging, and cold tests were ological measurements such as seed dry weight or moisconducted to assess seed quality. Canola attained PM when pods ture content is somewhat difficult, methods for deturned from green to greenish-yellow or light brown, and contained termining PM in canola based on morphological seeds ranging from brownish green to greenish brown and light brown.indicators are needed.The seeds were firm. Seed DWT did not change significantly from PM to HM. Seed MC at maximum DWT ranged from 203 to 360 g Four winter canola cultivars, Cascade, Crystal, Glacier, and Lirabon, and two spring cultivars, Topas and Westar, were

Genetic distance among canola cultivars was estimated through multivariate analysis. Thirty cultivars from various sources were analyzed and clustered based upon five morphological characteristics and yield components-crown diameter, number of branches plant(-1), number of pods plant(-1), number of seeds pod(-1) and yield plant(-1) -and placed in three distinct clusters. Two cultivars from each cluster were selected as parents and 15 partial-diallel inter- and intra-cluster crosses were made between the six selected parents and evaluated at two locations in Michigan in 1990/1991. The association between genetic distance and mid-parent heterosis was investigated. The correlation between genetic distance and heterosis was positive and highly significant for seed yield, number of pods plant(-1), and number of seeds pod(-1). Clustering, based on yield and yield-component traits, demonstrated that inter-cluster heterosis was greater than intra-cluster heterosis in the majority of cases.

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