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