Phenotypic evaluation of BC1F2 population to improve resistance to downy mildew (Peronosclerospora philippinensis) in high protein maize cultivar

Date

8-2016

Degree

Bachelor of Science in Agriculture

Major Course

Major in Agronomy

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Tonette P. Laude

Abstract

A backcross population was developed from crossing IPB Var 6 and UPLBCnN15, with IPB Var 6 as the recurrent parent and UPLBCnN15 as the donor parent. IPB Var 6 is a white QPM variety with susceptibility to downy mildew, and UPLBCnN15 is one of farmers? selected variety that was observed to have only 18.8% downy mildew incidence. The study was conducted at the Central Experiment Station, College of Agriculture, UPLB to assess the genetic variability and heritability for downy mildew resistance in BC1F2 families and to estimate the genetic improvement for downy mildew resistance from selected BC1F2 families. The experiment was consisted of 190 BC1F2 families and four checks (IPB Var6, UPLBCnN15, F1, and BC1F1), and was laid out in a single location unreplicated trial following an augmented design with 18 blocks. Evaluation for downy mildew infection was done at three different stages of infection (two, four and six weeks after plant emergence). The analysis of variance among entries for downy mildew infection revealed significant differences (Pr<0.01) at both stages II and III among BC1F2 families and among check entries. Thus, variability is high in the BC1F2 population. At stage III, broad-sense heritability was estimated as 53.38%, which implies that downy mildew resistance is largely affected by the environment. Hence, the inheritance of downy mildew resistance from UPLBCnN15 may be controlled by many genes with minor effects. Results showed that out of the 190 BC1F2 families, the 12 resistant to moderately resistant BC1F2 families had better resistance than IPB Var 6, F1 and BC1F1, and similar resistance for downy mildew with UPLBCnN15. Recombining the selected 12 BC1F2 families is expected to decrease downy mildew infection by 37.62%. Thus, this study demonstrated that the incorporation of downy mildew resistance from UPLBCnN15 to IPB Var 6 could provide broad spectrum resistance to downy mildew and selected families can be used for further studies for the improvement of the crop.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2016 A3 /S63

Document Type

Thesis

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