Effects of Day Length and Light Intensity on Growth of Barley V. Response by Plants in the Field to Night Interruption

For 12 cultivars of wheat grown under a 21°C day/16°C night temperature regime, spikelet number was closely related to grain number, but not to grain yield per ear as individual grain weights differed considerably between cultivars. However, when spikelet number was varied by day length or vernalization treatment, grain yield per ear was clearly dependent on spikelet number within each cultivar.An increase in spikelet number per ear was always associated with longer development. In cultivars with a pronounced response to vernalization (e.g. Late Mexico 120), the length of the period to floral initiation was of prime importance, because during this time potential spikelet sites were established; once floral initiation occurred, development of the inflorescence proceeded rapidly, and few further spikelet primordia were differentiated. In cultivars with no vernalization response (e.g. Triple Dirk), the duration of the period from floral initiation to terminal spikelet formation, during which all the spikelet initials appeared, determined spikelet number. The spikelet number of cultivars with a slight response to cold was associated with the lengths of both these periods.Spikelet number in Triple Dirk was modified by the number of long-day cycles to which plants were exposed; increase in the number of inductive cycles up to nine reduced the period from flOl'al initiation to the appearance of the terminal spikelet, and also reduced spikelet number per ear from 24 to 17. Exposure to only two longday cycles resulted in production of double ridges but caused slow inflorescence development thereafter, and there was an appreciable lag before a terminal spikelet appeared. However, development could be accelerated by exposure to further inductive cycles at any time before the spikelet primordia became swollen.

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“…Wislocka 1959; cf. also Paleg and Aspinall (1966) for barley], and by temperature and light intensity (e.g. Friend 1965).…”

Section: Introductionmentioning

confidence: 99%

Spikelet Number, Its Control and Relation to Yield Per Ear in Wheat

Rawson¹

1970

Aust. Jnl. Of Bio. Sci.

121

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“…Dans les montagnes des régions tempérées, le tallage herbacé (Kobold, 1974) (Paleg et Aspinall, 1966); -l'émission des talles herbacées cesse quand l'azote ne suffit plus aux besoins (Aspinall, 1961;Masle-Meynard, 1981) (Vincent, 1986), sont servies prioritairement (Masle, 1985 (Hétier, 1971 (Gosse et al, 1986) alors que la température limite la croissance en taille des végétaux (Durand, 1967 (Triboï et al, 1985;Gate et al, 1990 (Dagnélie, 1984 (Bachacou et al, 1981 …”

Section: Introductionunclassified