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Methodology: Experiments including brief times of shading (80 %, 7-10 days) amid flower start (Exp.1 and 2) or at interims between botanical ...
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FILLING IN THE GAPS: MODELING AS A SPUR TO RESEARCH IN SUNFLOWER A.J. Lobby, J.E. Cantagallo, C.A.Chimenti, M.C. Rousseaux and N. Trápani IFEVA, Facultad de Agronomía (Univ. Buenos Aires)/CONICET. email: INTRODUCTION Formulation and testing of OILCROP-SUN (Villalobos et al., Agron. J. 88:403-415, 1996) served to uncover various missing connections in data about how the sunflower crop reacts to the earth. A great part of the work with this yield did in Buenos Aires over the resulting years concentrated on these information holes. This notice compresses four contextual investigations. Issue : How does radiation amid the basic period (floret start to end seed setting period) influence grain number? Approach : Experiments including brief times of shading (80 %, 7-10 days) amid flower start (Exp.1 and 2) or at interims between botanical start and [anthesis+20d] (Exp. 3). Conclusions : Shading diminished floret primordia number per capitulum (Fig. 1) without changing grain set (filled grains/floret, information not appeared). Shading after floret separation was finished adjusted grain set differentially as per floret position and timing of shading (Fig. 2). Floret separation and the quick post-anthesis periods showed most extreme affectability to shading (Fig. 3). Reference : Cantagallo, J., Hall, A.J., 2000 – Reduction in the quantity of filled seed in sunflower ( Helianthus annuus L.) by light push. - 15 th International Sunflower Conference – Toulouse – France, pp. D-35-40 CASE 1 . Radiation and grain number determination. 3500 Fig. 1. Relationship between number of botanical primordia per peak and days from flower stage (FS) 5. (begin of floret differentation). Floret separation stops at FS 8. FS5 happened 32 days before anthesis, which, thus, occur 56 days after development. Fig. 2. Extent of seed setting, in every part of the head, as an element of the ontogenetic stage toward the start of the shading treatment. Fig. 3. Number of filled seed (communicated as rate of the Control treatment) as a component of time to anthesis for mid-shade interim. Open circle: shading medications from Exp. 2; filled circles: shading treatment from Exp. 3. LSD: minimum noteworthy contrast. FIG. 1 - 1 3000 - x/ - 3,976 2 (r =0,94) e 2500 - x/ - 5,261 2 (r =0,85) y =-180,3+361,9 e shading Exp. 1 2000 Primordia summit control Exp. 1 1500 shading Exp. 2 control Exp. 2 1000 Floral stage 8 FIG. 2 FIG. 3 500 Exp.1 Exp. 2 0 2 4 6 8 10 FS8 Anthesis Days from FS 5 Problem : No temperature reaction capacities for sunflower grain development were accessible at the time OILCROP-SUN was figured. Capacities for leaf reactions were utilized as a substitute. Approach : Plants were developed in controlled temperature glasshouses and incipient organism development rates and terms decided. Conclusions : Embryo development rate (Fig. 4) and term (Fig. 5) reaction capacities were resolved. The cooperation betwen these variables brought about persistent diminishments of fetus size with temperatures above 20°C (Fig. 6). The cardinal temperatures (T b , T pick ) for grain development term ( - 1°C and 34°C) were fairly diverse to those for leaves ( 4°C and 24°C). Reference : Chimenti et al., 2000, Field Crops Research (in press). CASE 2 . Temperature impacts on grain size. Figure 4. Relationship between developing life development rate and temperature for grains from the fringe position of the capitulum. Figure 5. Relationship between the proportional of developing life development span and temperature for grains from the fringe and transitional position of the capitulum. Figure 6. Relationship between relative fetus last weight (25°C last developing life weight = 100%) and temperature for grains from the fringe position of the capitulum. FIG. 4 FIG.6 FIG.5 Problem : Crops that produce high (> 4) LAI\'s before anthesis start to senesce so that LAI is really falling before anthesis. This doesn\'t happen in sparser shades. What rôle does light [intensity and quality] play in this procedure?. Approach : Experiments including varieties in shading, improvement with red (R) and far red (FR) light and product thickness (D) were utilized to test the speculation that light [intensity and quality] regulates basal leaf senescece in sunflower. Conclusions : Leaf span (LD) (time between most extreme leaf region and 20% starting chlorophyll substance) is subject to every day PAR receipt and is abbreviated by enhancement with FR (Fig. 7) and reached out by advancement with R (Fig. 8). Explores different avenues regarding tobacco lines overexpressing Phytochrome An affirmed the rôle of phytochrome in controlling leaf senescence (information not appeared). Particular leaf nitrogen of basal sunflower leaves relates all the more emphatically with mean day by day R/FR (Fig. 9) than with mean day by day PAR (information not appeared). References : Rousseaux et al., Physiol. Plant. 96: 217-224, 1996; Plant Cell Environ. 20: 1551-8, 1997; Crop Sci. 39: 1093-1100,1999; Physiol. Plant. 110: 000-000, 2000. CASE 3 . Control of pre-anthesis leaf senescence Fig. 7 . Leaf length (days after full development) as an element of mean every day episode PAR for leaves of segregated plants without (squares) or with (triangles) FR improvement. Fig. 8. Leaf length (days after full development) as an element of mean every day partial radiation measured 197 °Cd after full extension in basal leaves of a covering for leaves presented to extra R (triangles), extra green (circles [equivalent dosage of PAR to R]) and controls (squares). Full images: Exp. 1 - vacant images: Exp. 2 Fig. 9. Particular leaf nitrogen/mean every day R/FR relationship for basal leaves in coverings of shifting thickness. FIG. 9 FIG. 7 CASE 4 . Nitrogen consequences for leaf development Problem : The impacts of nitrogen on sunflower leaf photosynthesis had been depicted, however its impacts on sunflower leaf extension had not been concentrated on in awesome point of interest. Approach : Experiments including varieties in nitrogen supply or equal trades amongst high and low levels of N were utilized to look at extension of leaves at different levels of insertion and the impacts of N on cell division (prior and then afterward leaf development) and extension. Conclusions : Leaf extension rates in the semi direct period of development changed between levels of leaf insertion and with particular leaf nitrogen (SLN) (Fig. 10). The edge SLN for leaf development was significantly more noteworthy than that of greatest photosynthesis, fairly nearer to the SLN at which Pmax immerses (Fig. 11). Changes between levels of N accessibility at different phases of the development of rose leaves did not create critical changes in cell division if the changeover ocurred later than 10% of definite leaf size, cell extension kept on reacting to changeovers until the leaf had accomplished no less than 60% of its last size (information not appeared). N accessibility did, be that as it may, produce critical changes (by a variable of ca. x2) in cell number per leaf primordium at the phase of leaf appearance (Fig. 12). References : Trápani and Hall, Plant Soil 184: 331-40, 1996; Trápani et al., Ann. Bot. 84: 599-606, 1999. Fig. 10 Leaf extension rate amid the semi direct development stage (LER lg ) as an element of SLN for chose target leaves L8 through L25. Bends fitted by eye. Fig. 11 Diagram of envelopes for connections of Pmax\' and LER lg with particular leaf nitrogen for leaves of various positions and N supply levels. Bends fitted by eye to distant individual information focuses for every variable. Fig. 12 Dynamics of cell number (N cell ) in unemerged leaves 9 of hydroponically developed sunflower plants under high (  ) and low (  ) nitrogen supply. LER lg

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