Growth of florets of sunflower (Helianthus annuus L.) in relation to their position in the capitulum, shading and nitrogen supply

Sinsawat, Veerana; Steer, B. T.

doi:10.1016/0378-4290(93)90113-2

Cited by 18 publications

(7 citation statements)

References 10 publications

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“…However, estimating source size on the basis of leaf area implies that both the photosynthetic capacity per unit leaf area and the proportion of assimilates allocated from storage sinks into seeds were assumed to be identical in treated and untreated plants. The interpretation of the present results relies on these assumptions, although under certain circumstances both characteristics may change (Sinsawat & Steer 1993; Sadras et al . 1992).…”

Section: Discussionmentioning

confidence: 79%

Effect of source–sink ratio on seed set and filling in sunflower (Helianthus annuus L.)

Alkio

Schubert

Diepenbrock

et al. 2003

Plant Cell & Environment

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Poor seed development in sunflower may result from insufficient assimilate supply (source limitation). To test this hypothesis, the effects of changed source–sink ratio on seed set (measured as percentage of empty achenes) and seed filling (measured as dry mass per filled achene) in individual plants were investigated. Source–sink ratio, defined as leaf area per floret (LAF), was experimentally altered using invasive (floret removal, defoliation) and non‐invasive (pulse of chilling, short days or shading during leaf or floret initiation) treatments. Shading at floret initiation proved the most effective non‐invasive method. Generally, an increase, or decrease, in LAF improved, or impaired, both seed set and filling. Increasing LAF by 2.0 cm2[95% confidence interval (1.5, 2.5)] decreased the percentage of empty achenes by 36.9%‐points (−41.9, −30.9) and increased dry mass per filled achene by 20.1 mg (13.6, 26.7) in the capitulum centre. The effect of source–sink ratio on seed set was always strongest in the centre, whereas peripheral whorls were not affected. Achene mass was affected in all parts of the capitulum. It is concluded that source limitation is a major cause for empty achenes in sunflower plants grown under non‐stress conditions.

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Section: Discussionmentioning

confidence: 79%

Effect of source–sink ratio on seed set and filling in sunflower (Helianthus annuus L.)

Alkio

Schubert

Diepenbrock

et al. 2003

Plant Cell & Environment

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“…The highest performance in seed yield (Table 2), total N uptake, oil and protein production (Figure 2) was obtained with 100 kg ha -1 of N fertilizer (N100 treatment), confirming the results of other researches (Ujjanaiah et al, 1995;Dalla Costa and Giovanardi, 1996). Therefore, considering that sunflowers can absorb a high amount of residual N from the soil (Leto et al, 1997) and that they produce satisfactory yield with low N input (Sinsawat and Steer, 1993), fertilizer N should be applied only when required, according to total annual N uptake. Table 5 shows the sunflower yield components.…”

Section: Resultsmentioning

confidence: 99%

Four-year field experiment on nitrogen application to sunflower genotypes grown in semiarid conditions

Montemurro

Fornaro

2007

Helia

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A four-year field experiment was carried out to study the effects of different N levels on yield, yield components, N uptake and seed quality of sunflower genotypes grown in semiarid Mediterranean conditions. Five genotypes (four commercial hybrids and one newly selected genotype) and three N fertilization levels (0, 50 and 100 kg N ha -1 ) were compared over four years (1996, 1997, 1998 and 1999).Sunflower plants were taken at flowering time and their dry weight, leaf area index and total N content were determined. At maturity stage, yield, yield components, oil content, protein content, N uptake and seed quality were determined.The obtained results indicated significant differences in yield performance (seed, oil and protein production) throughout the years (from 2.52 t ha -1 in 1996 to 3.81 in 1999), confirming the need to use recommended genotypes and adjust fertilizer rates to crops requirements, especially in the Mediterranean environment where weather conditions are unpredictable and inconsistent. In fact, the genotypes showed different behavior in all years regarding total N uptake, seed, oil and protein production, indicating that the sunflower crop is responsive to agronomic management. The highest level of N fertilizer resulted in the best sunflower performance although, due to variations in year and genotype, fertilizer N could be applied according to total annual N uptake. Finally, the N uptake and the diameter of head were the most important parameters that influenced sunflower yield performance.

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“…In spite of these changes, the hierarchy in 1000-seed weight among the sectors remained the same in all cases. The greater weight of seeds nearer the periphery may be due to a larger supply of nutrients or to less competition among seeds as a consequence of the greater available space per seed in the receptacle (4,18). Seed oil content increased or decreased from the periphery to the center of the head, depending on the level of radiation intercepted and the genotype.…”

Section: Discussionmentioning

confidence: 99%

The effects of intercepted solar radiation on sunflower (Helianthus annuus L.) seed composition from different head positions

Santalla¹,

Dosio

Nolasco³

et al. 2002

J Americ Oil Chem Soc

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The effect of intercepted solar radiation during fruit filling on seed weight and oil content from seeds of three sectors of the head in two sunflower (Helianthus annuus L.) hybrids of low and high potential oil percentage was investigated. Seed weight in each sector depended on both the level of radiation intercepted (modified by shading and thinning plants) and the genotype grown. A higher level of intercepted solar radiation increased seed weight in each sector. Central seeds of shaded plants showed the lowest weight. The seed and kernel oil content hierarchy among the three sectors was modified only in the hybrid with high potential oil content. For each head sector, variations in seed oil content associated with changes in the level of intercepted radiation could be accounted for by changes in the kernel oil content, not in the kernel/seed ratio. Significant relationships were found between seed oil and kernel oil contents when analyses between treatments (R > 0.86) and sectors (R > 0.92) were carried out. These relationships together with the growing conditions of plants during seed filling, the genotype, and the seed position on the head are essential factors that should be taken into account when selecting seeds in sunflower breeding programs since they affect the commercial/industrial quality of seeds.Paper no. J9773 in JAOCS 79, 69-74 (January 2002). Means accompanied by the same letter for each sector are not significantly different at P < 0.05 using Tukey's method.

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Growth of florets of sunflower (Helianthus annuus L.) in relation to their position in the capitulum, shading and nitrogen supply

Cited by 18 publications

References 10 publications

Effect of source–sink ratio on seed set and filling in sunflower (Helianthus annuus L.)

Effect of source–sink ratio on seed set and filling in sunflower (Helianthus annuus L.)

Four-year field experiment on nitrogen application to sunflower genotypes grown in semiarid conditions

The effects of intercepted solar radiation on sunflower (Helianthus annuus L.) seed composition from different head positions

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