Data from research previously reported (MNL 58:116-118, MNL 60:77), which include 1985 results, were analyzed using the path coefficient technique with the aim of investigating the relationships of dry matter production and its components. F1 hybrids of crosses between flint type inbreds differing in photosynthetic activity were used. According to their influence on dry matter (DM) production the traits classified as first order factors were straw DM and kernel DM; second order factors were cob DM, ear length, leaf area index (LAI) and plant height (related to straw DM) and ear length, ear diameter, ear per plant, cob weight and 100 kernel weight (related to yield). Direct and indirect effect estimates are shown in Tables 1, 2 and 3. Both first order factors show similar direct effects on total dry matter production. Second order factors explain 61% of variance in straw and 82% in grain yield. Among them, ear length, cob DM and LAI are the main traits influencing straw through direct effects; in a similar way, cob weight, ear/plant number and ear diameter are shown to be the main traits influencing grain yield. Results are in general agreement with those obtained in 1983 and 1984. Differences are attributable to a higher ear/plant number in 1985 which caused diminution of ear size traits.

Table 1. Direct (D) and indirect effects of first order factors on yield.

Table 2. Direct (D) and indirect effects of first order factors on straw.

Table 3. Yield and straw effects on total dry matter.

Jaime R. Jatimliansky, Maria I. Urrutia and Miguel J. Arturi

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