Amc. Furlani et al., COMBINING ABILITY EFFECTS FOR P-EFFICIENCY CHARACTERS IN MAIZE CROWN IN LOW-P NUTRIENT SOLUTION, Maydica, 43(3), 1998, pp. 169-174
This study aimed at obtaining preliminary information on gene effects
of P-efficiency traits in maize grown under low-P concentration nutrie
nt solution, using genotypes from a diallel mating system. An experime
nt with 36 entries (eight parental lines and 28 single crosses) was co
nducted in the greenhouse, at the Experimental Center of Campinas, Ins
titute Agronomico (IAC), State of Sao Paulo, Brazil. Young plants (26
days of age) were evaluated for the P-efficiency characteristics, usin
g a randomized complete block design with five replications. The gener
al combining ability (GCA) and specific combining ability (SCA) inform
ation on crosses were obtained by using the method 4, model I analysis
of Griffing, for the variables: total (whole plant) dry matter (Tdm),
root dry matter (Rdm), total P content in the plant (Total-P) and the
P-use efficiency index (EI). In the average, the higher GCA estimates
for Tdm, Total-P and EI were obtained for the inbred L39, evidencing
the positive contribution of this parental to enhance these characters
in their Fl hybrids. For the Rdm character, the major contribution ca
me from L42. The most expressive estimates of SCA for the characters T
dm, Rdm and EI were detected for the crosses L42xL29, L40xL34, and L11
xL39; and, for Total-P, were the crosses L40xL34, L11xL39 and L39xL42.
L39 and L42 may be considered promissor inbred lines in maize breedin
g programs aimed at selecting and improving more efficient maize genot
ypes under low P conditions. The characters related to P-efficiency in
maize seedlings grown in low P nutrient solution were mainly controll
ed by additive effects, although the non-additive effects have also sh
own to be important. In a breeding program, plant selection in low-P n
utrient solution may be useful and successful when a large number of p
lants are tb be evaluated and when cycles of selection are alternated
with field evaluations.