Variability of Phytic Acid and Inorganic Phosphorus Contents in Seeds of Tropical Maize （Zea mays L.）

The correlation coefficients and scattering were studied in Ki and new inbred lines for phytic acid （PA） and inorganic phosphorus content （InP） content in seeds of tropical maize （Zea mays L.）. The understanding of the variability in PA and InP characters would be useful in a breeding program. A total of 16 Ki and 25 new inbred lines of tropical maize were planted in Completely Randomized Design （CRD） during late rainy season, 2007 to early rainy season, 2009 at Inseechandrastitya Institute for Crops Research and Development, Thailand. The result showed low correlation with no statistical significant between PA and InP contents in corn seeds performed either in different sources of inbred lines or years. For PA content, most of inbred lines were skewed toward high PA （〉 900 mg/100 g） both in Ki and new inbred lines in every year. The lowest PA value found in Ki inbred lines both in two years were Ki10, Ki15, Ki20, and Ki52.30A10-S11-43-1-3 was the lowest PA inbred lines observing in two years in new germplasm.

The Genetic Variances for the Phytic Acid and Inorganic Phosphorus Contents of Elite Inbred Lines in Tropical Maize

The study aimed to determine the genetic variances of phytic acid （myo-inositol 1,2,3,4,5,6 hexakis-dihydrogen phosphate） （PA） and inorganic phosphorus contents （InP） in grains of tropical maize （Zea mays L.）. The understanding of genetic variances in PA and InP in tropical maize would be useful for breeding management in tropical region. A total of 16 Ki inbred lines and 26 new inbred lines of tropical maize were planted in Completely Randomized Design （CRD） on the dry season 2008 at lnseechandrastitya Institute for Crops Research and Development, Thailand. The results showed that genotypic differences were highly significant （P 〈 0.01） for InP in both sources of germplasm, but genotype effect only was found significant in new inbred lines for PA content. The values for broad sense heritability （h2b） was generally lower on PA in maize grains compared with InP both in Ki and new inbred lines [h^2b of PA： 2.42 （Ki）, 14.18 （commercial hybrid extracted）; h^2b of InP： 32 （Ki） and 29.53 （commercial hybrid extracted）].

Composition of Starch and Protein in the Endosperm of Newly Generated Double Recessive Waxy and Opaque 2 Maize （Zea mays L.） Genotypes

Waxy maize with its pure amylopectin starch is the staple food of many ethnic minorities in hilly regions of Southeast Asia （SEA）. A combination of waxy and quality protein maize （QPM） traits would improve the quality of protein of waxy maize for human consumption. Double recessive waxy-QPM （wx-o2） genotypes had been generated from Southern Chinese material by haploid induction of crosses heterozygous for the two quality traits with an absolutely conserved waxy type and an improved amino acid profile. The vitreous kernel trait （due to the additional modifier genes present in QPM） was lost in the wx-o2 plant material; this may be due to the waxy mutation, this is anyhow desirable for acceptance as waxy maize is preferred due to its soft grains. The content of the quality limiting amino acid lysine was greatly increased in double recessive wx-o2 genotypes compared to standard waxy maize, but still with a high variation among genotypes for future improvement. Conclusively, it was indeed possible to combine two grain quality mutations successfully within one genotype and prototypes of double quality wx-o2 are available now to contribute to meet human requirements in essential amino acids and thus reduce malnutrition in various regions of Asia.