Nighttime temperature increment reduces grain yield in wheat and barley: A field study

GARCIA G; MF DRECCER; SERRAGO RA; MIRALLES DJ

Congreso; 6th. International Crop Science Conference, Bento Goncalvez,; 2012

Climate models predict reductions in the diurnal temperature range as consequence of greater nighttime minimum temperatures without an equivalent change in daytime maximum ones. A better understanding of the impact of nighttime temperature increment (NTI) ion the processes affecting wheat and barley grain yield and quality would lead to improved simulation capability in crop growth models and informed development of adaptation strategies. . The objective of this study was to analyse the impact of a NTI during the critical period on grain yield and its numerical and physiological components in, wheat and barley. The field study combined (i) two crop species: a bread wheat cultivar ( Baguette 13) and a two-row malting barley (cv. Scarlett), with (ii) two nighttime temperature regimes: a control (natural temperature) and an increment of ca. 5°C over from jointing to 10 days post-anthesis. The crops were modern high-yielding cultivars with similar flowering time, grown in the field at Facultad de Agronomía, Universidad de Buenos Aires (34°35´S, 58°29´W, 26masl) during 2011 without water, nutritional or biotic constraints. The NTI was achieved using transparent polyethylene chambers (2x2x1.5m) with an iron frame, equipped with electric heaters automatically controlled to increase inside temperature as a differential from outside temperature. NTI was set to 5C and the chambers were were placed on the crop at 8 pm and removed at 8 am. Grain yield was similarly reduced in both species (ca. 13%) due to a NTI of 5C, as consequence of a minor biomass accumulation (ca. 17%) without changes in harvest index. Reduction in biomass production was a result of combined effects on both growth and development process. NTI reduced the duration of the critical period (ca. 5 and 4 days in wheat and barley, respectively) without important differences in radiation interception efficiency, determining lower intercepted accumulated radiation (ca. 8 and 10% in wheat and barley respectively) with respect to the control. Interestingly, radiation use efficiency was also reduced (ca. 15 and 11% in wheat and barley, respectively) by NTI. Changes in grain number per unit of area associated with number of spikes (r=0.84, p=0.04 and r=0.77, p=0.07 in wheat and barley, respectively) explained most of the grain yield variation due to NTI (r=0.91, p