Male-sterile seed parents for the breeding of landrace-based topcross hybrids of pearl millet [Pennisetum glaucum (L.) R. Sr.] for the arid zone II. Downy mildew resistance, terminal drought tolerance, plant type and potential productivity

Abstract

In the first part of this study, topcross hybrids (TCHs) of pearl millet [Pennisetum glaucum (L.) R. Sr.] based on landrace pollinator showed a clear advantage in stability of grain and stover yields, compared to their pollinator, in arid zone environments. In this part of study, TCHs were evaluated for additional traits viz., downy mildew resistance, terminal drought tolerance, individual yield components and potential productivity in order to identify male-sterile (A) lines that would enhance the performance of TCHs in comparison to that of their landrace topcross pollinator (TCP). Downy mildew incidence in TCHs ranged from 0% to 60%: several A-lines (841 A, ICMA 88004, ICMA 91333, ICMA 92666, leMA 94111, ICMA 97333 and RMS 3A) produced hybrids resistant to all three downy mildew pathotypes. Many A-lines produced TCHs which had positive drought response index (DRI) and hybrids based on sixteen of the A-lines tested were significantly better than their pollinator in their ability to set and fill grain under stress conditions at Patancheru. None of the A-lines produced TCH with significantly better tillering than ERajPop, but ten of the TCHs had tillering at par with TCP. The majority of hybrids were significantly superior to their TCP for grain size, but this advantage was offset by significantly lower grain number panicle-1 in two-thirds of the TCHs. Eight of the TCHs had significantly greater growth rates, and consequently greater biomass, grain and/or stover yields than the TCP under high input conditions designed to assess potential productivity. Fertility restoration was adequate for the TCH of all A-lines except ICMA 90111 and ICMA 95333. Thus there are a number of opportunities to retain, in the TCH, favourable traits in the TCP and to improve less favourable ones as required.