Cool temperature-induced sterility in spring wheat ( Triticum aestivum L.) at high altitudes in Nepal: variation among cultivars in response to sowing date

• Published in: Field crops research 1998, Vol.55 (1), p.141-151
• Main Authors: Subedi, K.D., Floyd, C.N., Budhathoki, C.B.
• Format: Article
• Language: English
• Subjects: ALTITUD; ALTITUDE; Cool temperature; DATE DE SEMIS; ESTERILIDAD; FECHA DE SIEMBRA; FENOLOGIA; GENETIC VARIATION; Genotypic variation; INFERTILITE; INFERTILITY; NEPAL; PHENOLOGIE; PHENOLOGY; RESISTANCE A LA TEMPERATURE; RESISTENCIA A LA TEMPERATURA; SOWING DATE; Sterility; TEMPERATURE RESISTANCE; TRITICUM AESTIVUM; VARIACION GENETICA; VARIATION GENETIQUE; VARIEDADES; VARIETE; VARIETIES; Wheat
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/S0378-4290(97)00073-7

Cold stresses during the reproductive development of spring wheat ( Triticum aestivum L.) cause grain-set failure in the high altitudes (> 1500 m) of Nepal and other similar parts of the world. Field experiments were conducted during the winter seasons (October to April) of 1992/1993 and 1993/1994 at the Lumle Agricultural Research Center (1675 m) in Nepal to study the relations between temperature, phenology and grain set of spring wheat. Six cultivars of differing response to cool temperature were planted at 7-d intervals on six dates from 11 October to 15 November in both winters. The effect of temperature was evident on the times taken to heading, from heading to anthesis, total crop duration, grain set and grain yield. There was a seasonal difference in the extent of cold temperature: mean sterility was higher in 1992/1993 (19%) than in 1993/1994 (16%). Cool (< 10°C) temperature around heading prolonged the time to anthesis and led to greater degree of sterility in cold-susceptible cultivars. The cooler it was between heading and anthesis, the longer was the period between them and more grains failed to set. This period was longer when the crop was sown earlier, or when the crop faced a cooler period at and after heading and if the cultivars were cold susceptible. All the early heading cultivars studied (i.e., RR-21, BL-1022, BL-1135 and BL-1066) were cold susceptible and had significantly higher sterility than the late cultivars (NL-582 and Annapurna-3). The late-heading cultivars not only escaped the cool period, but also had inherent cold tolerance: the rate of development from heading to anthesis was rapid even under comparably cool temperatures. The reduction in grain set induced by cold stress also varied widely between cultivars and within a cultivar over sowing dates. Sterility was significantly greater (26%) in 11 October-planted crops followed by 18 October (22%), and reduced to 13–15% in the other later dates of sowing, which were not significant. If the period from heading to anthesis occurred in warm temperatures, the crop did not suffer much even if the pre-ear emergence stage of reproductive development coincided with extreme cold suggesting that the period from around heading until anthesis is critically sensitive to cold temperature. Mean temperatures during the period between heading to anthesis were more critical than minimum temperature as a cause of grain-set failure in cold-susceptible cultivars.