5 research outputs found
Enhancing Maize Grain Yield in Acid Soils of Western Kenya Using Aluminium Tolerant Germplasm
Abstract: Maize (Zea mays L.) is one of the world’s most important cereals and is a staple food for many people in developing
countries. However, in acid soils (pH < 5.5), its productivity is limited by aluminium (Al) toxicity, besides other factors. The
objectives of this study were to: develop Al tolerant maize inbred lines for a maize breeding program in Kenya, develop single cross
hybrids (SCHs) from some of the tolerant inbred lines and determine Al tolerance levels of the SCHs. One hundred and seventy five
inbreds and 49 SCHs were developed and screened in nutrient culture containing 0 or 222 μM using Relative Net Root Growth
(RNRG), hematoxylin staining (HS) and under Al saturated field conditions (44%-45.6%) at Sega and Chepkoilel. Seedling root
growth was inhibited in 95% of the inbreds. F1 hybrids obtained from inbreds varying in Al tolerance, exhibited tolerance equal to or
greater than that of the more tolerant parent indicating a positive transgressive inheritance to Al toxicity. Fifty eight percent of the F1
SCHs were heterotic for tolerance to Al toxicity. Al tolerance estimated by RNRG was well correlated to that of HS (r2 = 0.88, P <
0.005) but minimally correlated with the field estimates (r2 = 0.24-0.35), implying that RNRG can predict field selection under Al
toxic soils by between 24% and 35%. Plant breeders should therefore employ both approaches in selecting cultivars under Al stress.
This study has developed and identified Al tolerant inbreds and SCHs for use in the acid soils of Kenya and similar regions
Development of maize single cross hybrids for tolerance to low phosphorus
Low available phosphorus (P) is one of the major hindrances to maize (Zea mays L.) productivity in acid
soils. The objectives of this study were to: (1) develop P-efficient maize inbred lines, (2) develop single
cross hybrids from the P-efficient inbred lines, and (3) determine their response to P application in the
P-deficient acid soils of western Kenya. Ninety-eight inbred lines and 49 single crosses were developed
and screened at P-deficient (2.0 to 2.2 mg P/kg soil) soils of Sega and Bumala. Mean grain yield (GY) for
the hybrids was 75.3% higher with P-fertilizer than without P for the same hybrids. Thirty-three percent
(33%) of these hybrids were inefficient but responsive to P application, 27% were efficient and none
responsive, only 13% were efficient and responsive, while the rest were inefficient and non-responsive.
GY was positively correlated (r = 0.57**) with plant height (PH) and ear height (EH) (r = 0.60**) and PH
was correlated with EH (r = 0.86***). This study has developed and identified P-efficient maize
germplasm that can be utilized directly or in developing other hybrids for use in acid soils of western
Kenya and in other acid soils where P is limiting
Phylogenetic relationship among Kenyan sorghum germplasms based on aluminium tolerance
Eighty nine (89) sorghum lines sourced from various parts of Kenya were used to determine phylogenetic relationships based on 10 DNA fragments at AltSB loci with SbMATE, ORF9 and MITE primers. Nine lines of varying aluminium tolerance levels were selected to compare their SbMATE gene expression via the real-time PCR quantification of SbMATE gene expression. The sorghum line MSCR O2 expressed a thousandfold more SbMATEgene activity than the sensitive lines (MSCRM49, MSCRN84 and MSCRN61) under Al treatment. Analysis was done by agarose gel electrophoresis stained with ethidium bromide. The objective of this study was to assess the level of phylogenetic relationships among the Kenyan sorghum germplasms at a known Al tolerance locus. Hierarchical cluster analysis joined at 70% simple matching coefficient using average linkage similarity level produced nine groups in which 67 lines fell in three major clusters of 39, 15 and 13 lines each. The three Al tolerant lines MSCRO2, MSCRC1 and MSCRN60 were clustered together. Lines MSCRO2, MSCRC1 and MSCRN60, screened to be Al tolerant were genetically related at 70% average linkage similarity level and therefore recommend their further development as a food security measure in Kenya.Keywords: Aluminium (Al) toxicity, Sorghum bicolor, Sorghum bicolor multi-drug, toxic extrusion compound (SbMATE) gene expressionAfrican Journal of Biotechnology Vol. 12(22), pp. 3528-353
Cheprot et Al_PHYSIOLOGICAL CHARACTERIZATION OF KENYAN SORGHUM LINES.pdf
Eighty nine Kenyan sorghum lines were screened for tolerance to aluminium toxicity in nutrient
solution. Relative net root growth; root tip aluminium content and variation in organic acid
exudation were used to determine the tolerance or sensitivity of the sorghum lines at 148 μM Al for
six days. The lines showed variable reduction in root growth under the Al stress. On the basis of
the relative net root growths, three lines were tolerant, nineteen were moderately tolerant and sixty
seven were sensitive to the Al stress. The tolerant lines secreted up to five times more citrate
compared to sensitive lines under the Al treatment. All the lines secreted extremely low quantities
of malate under aluminium stress despite a significant positive regression (R 2 = 0.83) between
malate secretion and relative net root growth. There was a negative regression between relative
net root growth and root aluminium concentration (R2 = -0.79) among the selected sorghum lines,
and the sensitive lines accumulated up to three times the amount of Al compared to the tolerant
lines.. The Al tolerant sorghum lines were selected for improved sorghum production in acid soil.
The objectives of this study were to (i) identify Al tolerant Kenyan sorghum lines, (ii) investigate
tolerance mechanisms employed by Kenyan sorghum lines against Al stress
Phylogenetic Relationship among Kenyan Sorghum_Cheprot et al 2013.pdf
Eighty nine (89) sorghum lines sourced from various parts of Kenya were used to determine
phylogenetic relationships based on 10 DNA fragments at AltSB loci with SbMATE, ORF9 and MITE
primers. Nine lines of varying aluminium tolerance levels were selected to compare their SbMATE gene
expression via the real-time PCR quantification of SbMATE gene expression. The sorghum line MSCR
O2 expressed a thousandfold more SbMATEgene activity than the sensitive lines (MSCRM49, MSCRN84
and MSCRN61) under Al treatment. Analysis was done by agarose gel electrophoresis stained with
ethidium bromide. The objective of this study was to assess the level of phylogenetic relationships
among the Kenyan sorghum germplasms at a known Al tolerance locus. Hierarchical cluster analysis
joined at 70% simple matching coefficient using average linkage similarity level produced nine groups
in which 67 lines fell in three major clusters of 39, 15 and 13 lines each. The three Al tolerant lines
MSCRO2, MSCRC1 and MSCRN60 were clustered together. Lines MSCRO2, MSCRC1 and MSCRN60,
screened to be Al tolerant were genetically related at 70% average linkage similarity level and therefore
recommend their further development as a food security measure in Kenya