A path analysis was carried out on data obtained in 1984 from research aimed to determine the genetical basis of photosynthesis in maize and its relationships to yield and yield components (MNL 58:116-118, 1984). F1 hybrids of crosses between flint type lines differing in photosynthetic activity were used. The influence of the traits considered on yield was analyzed classifying them as (a) first order factors (ear width, ear length, 100 grain weight, cob weight and plant height) and (b) second order factors (leaf area index and apparent photosynthesis measured during grain filling). Direct and indirect effect estimates according to the path-coefficient technique are shown in Tables 1 and 2. The results indicate that: (1) The first order factors explain 91.1% of yield variations. Among those traits the direct effect of ear width on yield is notorious. Indirect effects of 100 grain weight (+) and ear length (-) through ear width appear to be important; (2) The two second order factors show lower determination coefficients on first order factors and, as should be expected, low correlation coefficients with yield (about 0.15).
Table 1. Direct* and indirect effects of first order factors on yield
Table 2. Effects of apparent photosynthesis on first order factors
Jaime R. Jatimliansky, Maria I. Urrutia and Miguel
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