Utility, Limitations and Lacunae

Abstract

There are no holidays in hybrid seed production, because for a single F₁ combination, emasculation and pollination have to be done repeatedly and carefully, the former being more tedious, time-consuming and harder than the latter. Furthermore, emasculation is especially difficult in plants with small and fragile flowers. This tedium of hand emasculation is greatly obviated by using mst lines. Even with most careful emasculation, over 5–15% selling occurs, in contrast to mst lines, where it is 1–5%. Furthermore, unlike in emasculation, the mst plants are undamaged, suffer less from various infections, can be fertilized more easily and produce higher yields. Moreover, pollen sterility relieves plants from the burden of pollen production and from the stress on plants during flowering. This results in a higher yield in mst’s compared to in those emasculated artificially especially in maize, rice, barley and pea. In maize, high plant populations, drought and hot weather are the types of stress which give advantage to mst lines (Duvick 1965). Since mst lines are effective females, in outbreeders the seed set on these lines is hybrid seed, being the product of NCP. On the other hand, in inbreeders pollination through pollen transfer from mft to mst parents has to be done. This pollen transfer is a formidable obstacle to large-scale hybrid seed production and is now being solved through use of mechanical and other devices.