Growth of sugar-beet crops including the influence of synthetic plant growth regulators

Abstract

Observations are presented from a crop of sugar beet grown in Cambridgeshire during 1978, and a field trial at Sutton Bonington during 1985 in which the influence of synthetic plant growth regulators (PGRs) daminozide, chlormequat, GA 4+7 and ethephon were compared.Several distinct patterns of growth were evident, being similar for both growing seasons and described by two intersecting straight lines. Early development was characterized by a slow rate of biomass accumulation, a dominance of foliage production with a constant but small root fraction (around 40%), a low specific leaf area and a slow but conservative rate of sucrose fractionation. Later in the season the rate of stand growth was both constant and maximal, the root fraction doubled, specific leaf area increased and the rate of sucrose accumulation rose markedly.Transitions between developmental phases occurred at various times dependent on variate under consideration. The onset of the main growth period began at the end of June, followed by an increase in the rate of sucrose accumulation about 2 weeks later. Finally, near the end of July, partition of assimilate into the root assumed a faster rate. Changes in the partitioning into both roots and sucrose are discussed in relation to the development of the secondary cambium.Generally there were no effects of PGRs on biomass accumulation, dry-matter partitioning, specific leaf area and sucrose accumulation. However, daminozide increased early canopy expansion and early dry-matter production but failed to influence biomass or sugar yield.

Growth and dry-matter partitioning in sugar beet

“…He identified two phases of constant allometry; an early phase which favoured leaf growth and a later phase dominated by storage-root growth. Green et al (1986) reached a similar conclusion; they also suggested that the transition from one phase to the next was induced by the onset of rapid division and expansion of cells within the secondary cambia of the root and that, perhaps, this was a response to shortening daylength.…”

“…The relationships between the weights of root dry matter or sugar and total dry matter were examined in terms of the slopes and break-point of a two-phase linear regression model, as used by Green et al (1986). The model was fitted using the Maximum Likelihood Program (MLP; Ross, 1980) with weighting to equalize the variance within the wide data range.…”

“…4). The observation by Green et al (1986) of a separation for one of their crops could be viewed as evidence that structures for accumulating sugar develop before the sugar is stored, i.e. the 'ripening' concept of Bouillene et al (1940), Bakhuyzen (1949) and Ulrich (1952Ulrich ( , 1955.…”

“…If successful this approach should provide valuable information on the magnitude of partitioning coefficients and the timing of any changes in these coefficients. In particular, the approach, by its nature, suggests that there is a critical stage at which partitioning coefficients change substantially, and Green et al (1986) suggest that the timing of this stage differs for root dry matter and sugar. These are important physiological suggestions that require further investigation.…”

Dry Matter Production and Partitioning Pattern in Sugar Beet

“…Terry (1968) stated that growth of the root slowly increases until about six weeks after emergence, and after that, the accumulation of dry matter in the root increases from the sum of the leaves and the petiole, thus developing separate stages for growth Leaf and root growth. Green et al (1986) stated that the transition from one stage to another may be due to the shortening of the day. On this basis, it is expected that the rapid root growth takes place in a short time period or at a certain stage of the plant growth period.…”