Effects of differences in date of ear emergence and height on yield of winter wheat

Abstract

SUMMARYEarly and late, and short and tall lines were selected from a cross between the winter wheat varieties Norman and Talent. All short selections carried the Rht2 dwarfing gene while the tall ones did not. The selections were compared in field experiments at the Plant Breeding Institute in Trumpington and at The Murrays Experimental Farm of the Scottish Crop Research Institute near Pathhead. In one of the experiments at Trumpington the plots were automatically sheltered from rain and the effects of withholding water before anthesis and withholding water during grain filling were studied.In all trials the early selections gave grain yields equal to or greater than the late selections. There were no differences in number of ears/m2 or in number of grains per ear between the early and the late selections. Mean weight per grain of the early selections was greater than that of the late selections.The short selections gave grain yields equal to or greater than the tall selections, except when water was withheld during grain filling in the sheltered experiment. There were no differences in number of ears/m2 between the short and the tall selections. The number of grains per ear was greater and mean weight per grain was less for the short selections than for the tall selections.It is concluded that for general fitness to U.K. conditions, new varieties should be semi-dwarf, but earlier than current varieties.

Assessment of drought resistance in pearl millet [Pennisetum americanum (L.) Leeke]. I. Factors affecting yields under stress

“…The responses of pearl millet to both stresses differed from those reported in wheat and barley (Day and Intalap 1970;Day et al 1978;Johnson and Kanemasu 1982;Innes et al 1985). In the studies cited the major effect of a pre-anthesis (midseason) stress was a reduction in number of ears per unit area, with a secondary effect on number of grains per ear.…”

“…The advantages of earliness in this type of stress have been documented in many other crops (e.g. Blum 1970;Fischer and Wood 1979;Innes et al 1985).…”

Quality and Value of Organic Grain from Contrasting Breadmaking Wheat Varieties and Near Isogenic Lines Differing in Dwarfing Genes

“…Mercia does not have a specific Rht gene but is, nonetheless, of comparable height to A va1on and Here ward. Despite the prevalence of shorter varieties in modem intensive agriculture older, and often taller, varieties have been considered to have certain potential advantages for organic growers such as the tolerance of weeds (Cosser et al, 1997), better acquisition of soil nitrogen (Cosser et al, 1994;Foulkes et al, 1994 ), provision of early bite in dual grazing plus grain production systems (Gooding et al, 1998), and sometimes a better tolerance of late droughts (Innes et al, 1985;Thompson et al, 1993).…”

Effect of drought stress during grain filling in near-isogenic tall and dwarf hybrids of pearl millet (Pennisetum glaucum)

“…Reductions in number of grains and grain mass under stress were generally similar in dwarf and tall isolines in wheat (Brandle & Knott 1986;Udden & Marshall 1989) and sorghum (Campbell et al 1975). In a controlled study with near-isogenic dwarf (Rht2) and tall lines in wheat, the dwarf lines yielded more than their tall counterparts in fully irrigated conditions and in early and late droughts, although the percentage reduction in the drought treatments was greater in the semidwarf lines than in the tall versions (Innes et al 1985). Dwarf millet thus appears to respond to drought stress in a manner similar to that of dwarf wheat and dwarf sorghum, although it resembles sorghum more than wheat in that there is no clearly established superiority of the dwarfs in favourable environments.…”

“…Hurd (1974) suggested that poorer root development of semidwarf wheats rendered them more vulnerable to drought stress than tall varieties. Innes et al (1985) found that water use was similar in the two height classes of wheat in the early drought treatment but that the tall varieties extracted more water in the late drought treatment. Other studies, however, have reported no differences in rooting pattern or water extraction pattern in semidwarf and tall varieties of wheat (Cholick et al 1977;Pepe & Welsh 1979;Holbrook & Welsh 1980) and barley (Irvine et al 1980).…”