Assessment of Agronomic Performance and Haploid Induction Rate of Tropically Adapted Inducer Maize Lines
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Date
2018
Authors
Nzamu, Janet Mwende
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Publisher
Kenyatta University
Abstract
Hybrid maize varieties are developed using inbred lines. Conventionally, inbred lines are developed by self-pollination, which takes 6-8 generations. The technology of doubled haploid (DH) is new and the most efficient in the development of inbred lines since complete homozygosity is achieved in 2 crop seasons. Haploid inducers have been refereed variedly as genetic stock which through crossing to a diploid plant, result in a mix of haploid and diploid kernels. These progeny segregates to diploid (2n) and haploid (n) kernels due to anomalous fertilization. The International Maize and Wheat Improvement Center (CIMMYT) and Hohenheim University have developed several tropicalized inducer Lines (TAILs) that have not been tested for haploid HIR under the Kenya maize growing environment. A study was therefore set up in collaboration with CIMMYT at the DH facility located at Kiboko in Makueni County to test seven TAILs (first generation TAILs 7, 8, 9, Hybrid 9×7 and 9×8 and second generation TAILs 008 and 009) for HIR in Kenya. The objective was to improve the efficiency of hybrid maize development using haploid inducers with good agronomic performance and highest haploid induction rate. A split plot arrangement was used in the experiment in which the inducers were the main plots while the female populations were the sub plots. Randomized complete block design (RCBD) was adopted with three replications. Three female populations (ligule less tester and two normal populations) were crossed with the seven TAILS. The F1 were germinated and the seedlings used to determine HIR of the Tails using their morphological plant characters. Pollen was harvested randomly from 10 plants of each haploid inducer line three days after pollen shed. TTC (2, 3, 5- triphenlytetrazolium chloride) solution was used as the staining technique of pollen at different times of day to determine pollen viability. Data collected was subjected to ANOVA using R- software version 3.2.3. Means of HIR and agronomic characters of the inducers were separated using the least significance difference (LSD) at 5% level of significance. The results showed that Tail 009 had the best plant and ear height, while Tail 7 had the best number of tassel braches and large tassel size. Pollen viability was high in the morning hours to noon and started to reduce in the afternoon hours. Despite this, pollen viability was above 90% in all the inducers, with TAIL 7 having the highest viability (98.45%) and TAIL 009 the lowest viability (92.77%). The ligule less tester and normal population 2 showed the highest HIR of 7.62-8.49% respectively; hence they can be used for the determination of HIR of target haploid inducer lines. Tail 8 and 9 had the highest HIR hence they can be used for haploid induction in target germ plasm. Plant height and HIR on the ligule less tester showed a positive correlation. The study was fundamental in identifying haploid inducer lines with high HIR for commercial development of homozygous lines and the results could lead to more efficient haploid induction in elite maize germplasm
Description
A Research Thesis Submitted In Partial Fulfillment of the Requirement for the Award of Masters of Science Plant Breeding in the School of Agriculture and Enterprise Development, Kenyatta University. November, 2018