A study of grain number in two contrasting wheat cultivars

1978 ◽  
Vol 29 (3) ◽  
pp. 431 ◽  
Author(s):  
PJ Bremner ◽  
JL Davidson

The origin of the grain number difference between two contrasting wheat cultivars (WW 15, Mexican semidwarf; Timgalen, Australian) was studied in terms of (i) the production and distribution of dry matter during the pre-anthesis development of the ear; (ii) the number of florets initiated; and (iii) interaction between grains during grain set. Grain yield was much more closely related to harvest index than to total dry weight, and harvest index appeared to be largely a function of the number of grains produced per unit area. The difference in grain number between the cultivars bore no relation to the number of florets initiated by them. Nor was the inhibition of grain set in the distal florets of spikelets by rapid growth of grains in basal florets involved. Large differences in grain number occurred between the cultivars where there was no detectable difference between them in the production and distribution of dry matter during pre-anthesis ear development, i.e. the semidwarf cultivar was superior in setting grains for some reason other than the pattern of distribution of dry matter between grain and straw.

1990 ◽  
Vol 26 (4) ◽  
pp. 413-427 ◽  
Author(s):  
S. N. Azam-Ali ◽  
R. B. Matthews ◽  
J. H. Williams ◽  
J. M. Peacock

SUMMARYThe productivity of each component of a sorghum/groundnut intercrop and its constituent sole crops is determined in terms of a ‘Crop Performance Ratio’ (CPR) defined as the productivity of an intercrop per unit area of ground compared with that expected from sole crops sown in the same proportions. The CPR allows productivity, intercepted radiation and seasonal transpiration to be compared so that conversion coefficients for radiation (e; g MJ−1) and dry matter/water ratios (q; g kg−1) can be calculated for each intercrop component and its constituent sole crops. In this experiment, CPR for total dry weight in the intercrop was 1.08 and that for reproductive yield was 1.27. These advantages in overall productivity and yield were typical of those reported elsewhere for sorghum/groundnut intercrops. The proportional increase in total dry matter in the intercrop was largely a result of its greater interception of radiation. The further advantage in reproductive yield was a consequence of an improved harvest index in the sorghum component of the intercrop (0.64) compared with that of its sole crop counterpart (0.55).


1980 ◽  
Vol 95 (2) ◽  
pp. 457-469 ◽  
Author(s):  
D. J. Greenwood ◽  
T. J. Cleaver ◽  
Mary K. Turner ◽  
J. Hunt ◽  
K. B. Niendorf ◽  
...  

SUMMARYFifty-six experiments, each with 15 levels of P fertilizer in the presence of excess N and K fertilizer, were carried out on adjacent sites of the same field where the soil was maintained at the same low P status. Yields, in every experiment where there was a response, were related to level of P fertilizer by a diminishing-retums type curve, and fitted an inverse polynomial equation with a single parameter to define responsiveness. Responsiveness of many crops were similar but there were, nevertheless, considerable inter-crop differences.Applications of P fertilizer increased the % P in the dry matter of lettuce and spinach as well as yields. They increased the % P in the Cruciferae and Chenopodiaceae without appreciably affecting yield. Conversely, theyhad little effect on the % P of leeks, onions, broad beans and French beans but increased yields.When the optimum levels of P fertilizer were applied, % P (in the entire plant) of the different crops was negatively correlated with total dry weight per unit area and total uptake of P was related by a single curved relationship to total dry weight. In addition, the difference between the % P in the foliage and in the storage roots of the various root crops was asymptotically related to mean plant weight.Percentage recovery of added P (100 kg/ha) by the different crops was largely determined by the total weight of dry matter. It varied from 1% when crop dry weight was 2 t/ha to 12% when it was 15 t/ha.Applications of phosphate suppressed leaf scorch of spinach. On occasion they alleviated stem rot in summer cabbage and influenced the bolting of onions and the number of defective Brussels sprouts. Otherwise, the effects on quality were small.


1989 ◽  
Vol 112 (3) ◽  
pp. 359-375 ◽  
Author(s):  
A. E. Abuzeid ◽  
S. J. Wilcockson

SummaryIn field experiments in 1983–85 in Northumberland, UK, early sowings achieved a leaf area index (LAI) of 3·5, capable of intercepting 90–95% total incident solar radiation, earlier than late sowings. As there was a close relationship between total dry weight, bud dry weight and amount of intercepted solar radiation, early sowings invariably outyielded later ones. The efficiency of energy conversion of radiation was 1·28, 2·05 and 2·11 g/MJ for total dry weight and 0·97, 0·83 and 0·67 g/MJ for bud dry weight in 1983, 1984 and 1985, respectively. Harvest index ranged from ca. 25% in 1985 to 40% in 1984.Increasing plant density from 2·22 to 6·66 plants/m2 advanced and increased maximum LAI and total and bud dry weight per m2 but had an adverse effect on distribution of dry matter. Maximum total dry weights were achieved at or slightly after maximum LAI. The onset of rapid bud growth coincided with maximum total standing dry weight and was advanced by early sowing but largely unaffected by plant density.Early-sown crops produced more buds than late-sown ones because of a longer growing season. Plant density had a large effect on the number of buds per m2, which was almost directly proportional as the number of buds per plant was not severely affected. However, individual bud size was restricted as a result of competition for assimilates. Approximately 80% of buds finally recorded had been produced before significant bud growth had occurred.Total bud fresh yields averaged over all sowing dates reached 17 t/ha in 1983 and 31 t/ha in 1984. The lower yield in 1983 was the result of late sowing caused by unfavourable weather. Early sowings significantly outyielded late ones because of earlier onset of rapid bud growth which gave a longer growing period. The effect of plant density on total sprout yield was less pronounced than that of sowing date but effects on yield per plant were large.Yields of buds in the freezing grade (20–30 mm) increased rapidly between late September and early to mid-November in both 1983 and 1984 and reached 7·5 and 8·8 t/ha, respectively. The difference between freezing-grade yields in the two years (1·3 t/ha) was much less than the difference between total yields (14 t/ha). Late sowing in 1983 restricted bud growth resulting in a higher proportion in the freezing grade. Plant density had a greater effect on freezing-grade yield than on total yield. Low planting densities gave high yields of small buds at early harvests but denser planting gave higher yields at later harvests. Generally, increases in bud fresh weight over the harvest period were greater than those in bud dry weight because of water uptake. The average dry matter content of buds declined by 2–5 % from October to January.The experiments confirmed that manipulation of sowing date and planting density is an effective way of spreading harvest date throughout the season in order to achieve an orderly sequence of crops for the fresh market and for processing.


1990 ◽  
Vol 26 (4) ◽  
pp. 413-427 ◽  
Author(s):  
S. N. Azam-Ali ◽  
R. B. Matthews ◽  
J. H. Williams ◽  
J. M. Peacock

SUMMARYThe productivity of each component of a sorghum/groundnut intercrop and its constituent sole crops is determined in terms of a ‘Crop Performance Ratio’ (CPR) defined as the productivity of an intercrop per unit area of ground compared with that expected from sole crops sown in the same proportions. The CPR allows productivity, intercepted radiation and seasonal transpiration to be compared so that conversion coefficients for radiation (e; g MJ−1) and dry matter/water ratios (q; g kg−1) can be calculated for each intercrop component and its constituent sole crops. In this experiment, CPR for total dry weight in the intercrop was 1.08 and that for reproductive yield was 1.27. These advantages in overall productivity and yield were typical of those reported elsewhere for sorghum/groundnut intercrops. The proportional increase in total dry matter in the intercrop was largely a result of its greater interception of radiation. The further advantage in reproductive yield was a consequence of an improved harvest index in the sorghum component of the intercrop (0.64) compared with that of its sole crop counterpart (0.55).


1988 ◽  
Vol 111 (2) ◽  
pp. 221-232 ◽  
Author(s):  
M. M. Husain ◽  
G. D. Hill ◽  
J. N. Gallagher

summaryThe response of 4 crops of autumn- and spring-sown field beans cv. Maris Bead to irrigation applied during the vegetative, flowering and pod-filling phases was examined during 1981–2 and 1982–3. The crops, grown on a Templeton silt-loam, were irrigated weekly in amounts equal to the difference between the estimated evapotranspiration and rainfall of the previous week using trickle irrigation.Seed yield of fully irrigated autumn- and spring-sown crops (averaged over the two seasons), was 5·2 and 3·3 t/ha respectively, about 45% greater than the yield of unirrigated crops. The increase in yield due to irrigation was mainly associated with an increase in total dry matter (TDM) production as harvest index varied little within each sowing. The yield response to each mm of applied irrigation water ranged from 0 to 9 kg/ha and did not appear to be related in any way to the developmental phase of the crop when irrigation was applied.Seed yield within each sowing was closely correlated with the number of beans per unit area and the number of pods per plant. Autumn sowings yielded about 55% more than spring sowings mainly due to a higher harvest index which was associated with a much heavier mean weight per bean.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yingying Sun ◽  
Suiqi Zhang ◽  
Jiakun Yan

AbstractEight dryland winter wheat cultivars (Triticum aestivum L.), which were widely cultivated from the 1940s to the 2010s in Shaanxi Province, China, were selected and grown in plots, and two water treatments (irrigation and drought) were used to identify the contribution of ears, leaves and stems to grain weight and grain number associated with cultivar replacement. The plant height and stem dry weight of the dryland wheat decreased significantly during the cultivar replacement process, but there was a remarkable increase in the dry matter translocation of stems under irrigation. Shaded-ear and defoliation treatment could decrease the grain number and grain weight, and the grain weight was more influenced. Both the leaf and ear are important photosynthetic sources for dryland wheat, and the contribution of ear assimilates showed a significant increase over time; however, the contribution of leaf assimilates showed a negative correlation with cultivation over time. The accumulation of stem assimilates and ear photosynthesis both increased the grain weight potential. In the future breeding process, cultivars with more assimilates stored in the stem and greater assimilative capacity of ears, especially a greater contribution of ear assimilates, are expected to increase the grain yield.


Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 751-757 ◽  
Author(s):  
David T. Patterson ◽  
Maxine T. Highsmith ◽  
Elizabeth P. Flint

Cotton, spurred anoda, and velvetleaf were grown in controlled-environment chambers at day/night temperatures of 32/23 or 26/17 C and CO2concentrations of 350 or 700 ppm. After 5 weeks, CO2enrichment to 700 ppm increased dry matter accumulation by 38, 26, and 29% in cotton, spurred anoda, and velvetleaf, respectively, at 26/17 C and by 61, 41, and 29% at 32/23 C. Increases in leaf weight accounted for over 80% of the increase in total plant weight in cotton and spurred anoda in both temperature regimes. Leaf area was not increased by CO2enrichment. The observed increases in dry matter production with CO2enrichment were caused by increased net assimilation rate. In a second experiment, plants were grown at 350 ppm CO2and 29/23 C day/night for 17 days before exposure to 700 ppm CO2at 26/17 C for 1 week. Short-term exposure to high CO2significantly increased net assimilation rate, dry matter production, total dry weight, leaf dry weight, and specific leaf weight in comparison with plants maintained at 350 ppm CO2at 26/17 C. Increases in leaf weight in response to short-term CO2enrichment accounted for 100, 87, and 68% of the observed increase in total plant dry weight of cotton, spurred anoda, and velvetleaf, respectively. Comparisons among the species showed that CO2enrichment decreased the weed/crop ratio for total dry weight, possibly indicating a potential competitive advantage for cotton under elevated CO2, even at suboptimum temperatures.


1977 ◽  
Vol 4 (5) ◽  
pp. 785 ◽  
Author(s):  
I Sofield ◽  
LT Evans ◽  
MG Cook ◽  
IF Wardlaw

Controlled-environment conditions were used to examine the effects of cultivar and of temperature and illuminance after anthesis on grain setting and on the duration and rate of grain growth. After an initial lag period, which did not differ greatly between cultivars, grain dry weight increased linearly under most conditions until final grain weight was approached. Growth rate per grain depended on floret position within the ear, varied between cultivars (those with larger grains at maturity having a faster rate), and increased with rise in temperature. With cultivars in which grain number per ear was markedly affected by illuminance, light had relatively little effect on growth rate per grain. With those in which grain number was less affected by illuminance, growth rate per grain was highly responsive to it, especially in the more distal florets. In both cases there was a close relation between leaf photosynthetic rate as influenced by illuminance, the rate of grain growth per ear, and final grain yield per ear. The duration of linear grain growth, on the other hand, was scarcely influenced by illuminance, but was greatly reduced as temperature rose, with pronounced effects on grain yield per ear. Cultivars differed to some extent in their duration of linear growth, but these differences accounted for less of the difference in final weight per grain than did those in rate of grain growth. Under most conditions the cessation of grain growth did not appear to be due to lack of assimilates.


Weed Science ◽  
1986 ◽  
Vol 34 (6) ◽  
pp. 876-882 ◽  
Author(s):  
David T. Patterson ◽  
Ann E. Russell ◽  
David A. Mortensen ◽  
Robert D. Coffin ◽  
Elizabeth P. Flint

Texas panicum (Panicum texanumBuckl. # PANTE) is a native of the Southwest, now increasing as a weed throughout the southern United States, whereas wild proso millet (Panicum miliaceumL. # PANMI) is an introduced weed currently increasing in importance in the northern Midwest. In controlled-environment chambers, both species produced more tillers, greater leaf area, and more total dry weight at 30/24 C day/night (simulated growing season temperature in Georgia) than at 24/18 C (simulated growing season temperature in Minnesota). Texas panicum accumulated more dry matter at 30/24 C than did wild proso millet, while wild proso millet accumulated more dry matter at 24/18 C than did Texas panicum. When the two species were grown together, Texas panicum was the superior competitor at 30/24 C while wild proso millet was superior at 24/18 C. Exposure to short photoperiods at an intermediate temperature of 27/21 C accelerated flowering and limited vegetative growth in both species. In the range of photoperiods (10 to 16 h) examined, wild proso millet always flowered earlier and, consequently, produced less vegetative growth than Texas panicum. Its responses to temperature and photoperiod indicate that wild proso millet probably would be competitively inferior to Texas panicum and other adapted grass weeds in the southern United States.


1971 ◽  
Vol 77 (3) ◽  
pp. 445-452 ◽  
Author(s):  
R. W. Willey ◽  
R. Holliday

SUMMARYTwo barley experiments are described in which a range of plant populations were shaded during different periods of development. Shading during the ear development period caused considerable reductions in grain yield, largely by reducing the number of grains per ear. Shading during the grain-filling period caused no reduction in grain yield. It is suggested that under conditions of these experiments there was probably a potential surplus of carbohydrate available for grain filling and that grain yield was largely determined by the storage capacity of the ears. The importance of the number of grains per ear as an indicator of individual ear capacity is emphasized.The effects of plant population on grain yield and its components are also examined. It is concluded that the number of grains per ear is the component having greatest influence on the decrease in grain yield at above-optimum populations and attention is again drawn to the possible importance of ear capacity. It is argued that on an area basis the number of grains per unit area may give a good indication of ear capacity. Examination of this parameter shows a close relationship with grain yield per unit area for both the shading and population treatments. It is particularly evident that a decrease in grain yield at high populations was associated with a comparable decrease in the number of grains per unit area. It is suggested that this decrease in grain number may be due to a lower production of total dry matter during ear development rather than an unfavourable partitioning of this dry matter between the ear and the rest of the plant. This lower production of total dry matter is attributed to the crop growth rates of the higher populations having reached their peak and then having declined before the end of the ear development period. This crop growth rate pattern, through its effect on grain number per unit area, is put forward as the basic reason why, in the final crop, grain yield per unit area decreases at above-optimum populations.


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