Development of downy mildew resistant maintainer inbreds (B lines) of Pearl millet for Arid environment

Abstract

Developing early maturing downy mildew resistant male sterile lines of pearl millet, which are also well adapted to the harsh climatic conditions of western Rajasthan, forms an important aspect of the pearl millet breeding programme. To achieve this goal crosses were made among 18 maintainer lines (B lines) suitable for this region. Eighteen crosses found resistant to downy mildew were selfed to obtain F₂ populations. These F₂ populations were evaluated for downy mildew disease at the Central Arid Zone Research Institute, Jodhpur. Disease incidence among populations ranged from 0 to 82% with mean downy mildew incidence of 41% and coefficient of variability 61%. F₂ population resulting form the cross ICMB 95444 x ICMB 93333 was free from downy mildew followed by ICMB 95111 x ICMB 93333, which showed only 6% downy mildew incidence. Five hundred and ninety three F₃ progenies were selected from these F₂ populations. Further evaluation of these F₃ progenies against Jodhpur pathotype of downy mildew revealed that selections from segregating populations of crosses ICMB 95444 x ICMB 94555 gave maximum number (35) of resistant progenies. It was observed that F₂ populations showing higher disease incidence produced less number of resistant F₃ progenies, also disease resistant selections made in the F₂ populations continued to show downy mildew resistance in the F₃ generation. This showed that selection for disease resistance was effective in the F₂ populations. The resistant F₃ progenies were carried forward by pedigree breeding to F₆ and are being utilized in backcrossing for developing new male sterile lines of pearl millet for this region.