Growth and yield of sorghum lines extracted from a population for differences in osmotic adjustment

1995 ◽  
Vol 46 (1) ◽  
pp. 61 ◽  
Author(s):  
T Tangpremsri ◽  
S Fukai ◽  
KS Fischer

From 47 S2 lines which had been extracted from a random mated population of sorghum, eight lines for a glasshouse experiment and four lines for a field experiment were divergently selected for variation in osmotic adjustment, and were grouped into two, High and Low osmotic adjustment (OA). Both the glasshouse and field experiments examined whether osmotic adjustment modified the plants' response to soil water deficit and also whether grain sink demand for assimilates, varied by removal of 50% spikelets, affected osmotic adjustment. In each experiment, there were well-watered control and water stress treatments. In both experiments, the dawn osmotic potential in the High OA group was always lower than in the Low OA group under water limiting conditions, and the difference was significant after anthesis. The difference in osmotic potential was about 0.1 MPa in the field and up to 0.25 MPa in the glasshouse. In the glasshouse experiment, removal of 50% spikelets at anthesis significantly decreased osmotic potential during grain filling, suggesting that osmotic adjustment is influenced by the availability of assimilates in the leaves. Under well-watered conditions, the two groups behaved very similarly in terms of maximum leaf area, green leaf area retention during grain filling, total dry matter production, grain yield and grain number in both experiments. Under water-limiting conditions, the High OA group produced larger maximum leaf area and had better leaf retention during grain filling. Despite similar water use, total dry matter was also significantly higher in the High OA group though the difference was small. Grain number was also greater in this group in both experiments, whereas grain yield was significantly higher in the High OA group in the field, but not in the glasshouse where severe water stress developed more rapidly. It is concluded that the adverse effect of water stress can be reduced by adopting sorghum genotypes with high osmotic adjustment. However, selection for high osmotic adjustment needs to ensure that osmotic adjustment is not solely due to small head size.

1991 ◽  
Vol 42 (5) ◽  
pp. 759 ◽  
Author(s):  
T Tangpremsri ◽  
S Fukai ◽  
KS Fischer ◽  
RG Henzell

Two sets containing large numbers (23 and 47 entries) of sorghum genotypes were grown in the glasshouse to examine the effect of osmotic adjustment on water extraction, dry matter growth and grain yield. Water stress was developed in two periods, one before and one after anthesis. The results were similar in the two experiments despite a large difference in the genetic background of the plant material. Since osmotic potential did not differ significantly among genotypes before water stress was induced, osmotic potential obtained under stress was used directly to indicate the genotype's ability to adjust osmotically. Osmotic adjustment was positively associated with green leaf area retention during grain filling and to root length density at 70 cm depth. Genotypes with high osmotic adjustment used more water during the second drying period. As a result, total dry matter was well related to osmotic adjustment during grain filling, but grain yield was negatively associated with osmotic adjustment in one experiment and not significantly related in the other. When comparison was made for lines which had similar leaf water potential during early stages of growth but which differed in osmotic adjustment during grain filling, there was still a positive effect of osmotic adjustment on total dry matter. This suggests that the positive effect was not caused by large plants extracting more water during early stages of growth, but was due to the difference in line's ability to extract water during grain filling.


1998 ◽  
Vol 49 (4) ◽  
pp. 687 ◽  
Author(s):  
S. B. Utzurrum Jr ◽  
S. Fukai ◽  
M. A. Foale

With development of water stress during grain filling, sorghum crops lose green leaves, and nitrogen (N) is remobilised from the leaves to grain. Supplementary N application just before anthesis may reduce leaf senescence, contributing to dry matter production during grain filling and, hence, grain yield. This hypothesis was tested using 2 sorghum hybrids which were known to differ in capacity for osmotic adjustment and the ability to retain green leaves under water stress, in a rainout shelter experiment in south-east Queensland. When N was applied at depth (>70 cm) where water was available, all N applied was apparently taken up by the plants, resulting in reduced leaf senescence, particularly for leaves in the middle layer. Remobilisation of N from leaf to grain during grain filling was reduced by the supplementary N application. Both stem and leaf were the source of remobilised N which contributed about 65% of the total grain N without supplementary N application, this being reduced to about 30% with N application The hybrid with known high osmotic adjustment had greater total above-ground dry matter, particularly stem dry matter, at anthesis than the other, providing more material for translocation to fill grains. It also maintained greater leaf area during early stages of grain filling. This hybrid produced significantly higher yield (465 v. 412 g/m2) only when supplementary N was applied. Without supplementary N application, their yields were similar at about 350 g/m2. It is concluded that provided N is taken up by the sorghum plants, late N application is effective in increasing grain yield under water-limiting conditions. Cultivars, however, differed in their responses to the application.


1990 ◽  
Vol 41 (1) ◽  
pp. 51 ◽  
Author(s):  
JM Santamaria ◽  
MM Ludlow ◽  
S Fukai

The contribution of osmotic adjustment to grain yield in Sorghum bicolor (L.) subjected to water stress before anthesis was studied using six entries. Three of the entries (Goldrush, E57, and DK470) were selected for high osmotic adjustment and the other three (Texas 6 1 OSR, Texas 67 1, and SC 219-9-1 9-1) for low osmotic adjustment, and divided into early, intermediate and late maturity groups. Entries were either well watered, or subjected to a 41-day period of water shortage prior to anthesis and well watered for the remainder of their growth. Entries selected for higher osmotic adjustment developed higher levels of osmotic adjustment during the pre-anthesis stress period than those selected for low osmotic adjustment in intermediate and late maturity groups, but not in the early group. However, the level of osmotic adjustment was not related to the maturity group, when water stress was imposed at the same developmental stage. Entries with high osmotic adjustment produced higher grain yields than those with low osmotic adjustment. The response varied from 15% for the mean of all maturity groups to 34% for the mean of intermediate and late groups, where there were significant differences in osmotic adjustment. The higher mean grain yield was due mainly to a larger grain number (19%). Even though entries with high osmotic adjustment bad a greater root length, soil water extraction and dry matter production during the pre-anthesis stress period, there was no significant difference in dry matter yield at physiological maturity between low and high osmotic adjustment groups. Consequently, the higher mean grain yield was related solely to a higher harvest index (27%), which was associated with a higher distribution index (25%) and a higher grain number (19%). A detailed analysis is given of the mechanisms by which osmotic adjustment contributed to grain yield in plants subjected to a pre-anthesis stress.


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.


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.


1988 ◽  
Vol 110 (1) ◽  
pp. 71-79 ◽  
Author(s):  
P. Q. Craufurd ◽  
F. R. Bidinger

SummaryThe phenotype of medium duration pearl millet varieties grown in West Africa differs from that of the shorter duration millets grown in India. African varieties are usually much taller, have longer panicles, fewer productive tillers, and a lower ratio of grain to above-ground dry-matter (harvest index). The effect of crop duration on plant phenotype was investigated in two hybrids using extended daylengths to increase the duration of the vegetative phase (GSl: sowing to panicle initiation). The two hybrids, 841A × J104 and 81A × Souna B, were considered to represent the Indian and African phenotype, respectively. Tiller production and survival, leaf area, and dry-matter accumulation and partition, were monitored over the season. Grain yield and its components were determined at maturity.The two hybrids responded similarly to the short and long daylength treatments. The duration of GSl was increased from 20 to 30 days, resulting in increased number of leaves, leaf area, and stem and total dry-matter accumulation; there was no effect on tiller production and survival, or on panicle growth rate. Grain yield was, therefore, the same in both GSl treatments, and harvest index (HI) was much reduced in the long GSl treatment owing to the increased stem growth. One evident effect of a longer GSl was on dry-matter partitioning between shoots; partitioning to the main stem (MS) was increased, whereas partitioning to the tillers was reduced.There was no difference in crop development, growth or yield between the two hybrids in either GSl treatment. The only significant differences were in the efficiency with which intercepted radiation was converted to dry matter, which was greater in 841A × J104 than in 81A × Souna B, and in the balance between MS and tillers; the grain yield of the MS was significantly greater in 81A x Souna B than in 841A × J104, but at the expense of number of productive tillers.The results demonstrate that both African and Indian phenotypes are equally productive under good agronomic conditions. The lower HI in longer duration African millets is a consequence of a much extended stem growth phase and therefore increased competition between stem and panicle during grain filling. Possible ways to increase grain yield in the medium duration African millets are considered.


1990 ◽  
Vol 41 (1) ◽  
pp. 67 ◽  
Author(s):  
MM Ludlow ◽  
JM Santamaria ◽  
S Fukai

The contribution of osmotic adjustment to grain yield in Sorghum bicolor (L.) subjected to water stress between anthesis and maturity was studied using six entries. Three of the entries (Goldrush, E57, and DK470) were selected for high osmotic adjustment and the other three (Texas 610SR, Texas 671, and SC 219-9-19-1) for low osmotic adjustment, and divided into early, intermediate and late maturity groups. Entries were either well watered, or subjected to a 50-day period of water shortage after anthesis following being well-watered prior to anthesis. Entries selected for high osmotic adjustment had mean values of osmotic adjustment at the end of the post-anthesis stress more than double those selected for low osmotic adjustment. The corresponding mean grain yield of entries with high osmotic adjustment were 24% higher than that of entries with low osmotic adjustment. The higher yield was due to both more and larger grains, and it was associated with higher harvest index and distribution index. At best, the difference in dry matter at maturity could explain only a few per cent of the difference in grain yield between entries with low and high osmotic adjustment. Water stress prior to anthesis (previous paper) reduced yield more than a post-anthesis stress of the same intensity. However, osmotic adjustment was equally effective in minimizing the reduction in grain yields in both stages. The use of osmotic adjustment as a selection trait in programs to improve the yield of grain sorghum is briefly discussed.


1994 ◽  
Vol 45 (5) ◽  
pp. 965 ◽  
Author(s):  
M Cooper ◽  
DE Byth ◽  
DR Woodruff

Wheat improvement in Australia has made extensive use of germplasm developed by the International Maize and Wheat Improvement Center (CIMMYT). The opportunity for further yield improvement in Queensland was investigated by comparing CIMMYT lines and Queensland cultivars in irrigated and dryland environments at three locations. CIMMYT lines were identified, with greater than 20% yield advantage in individual environments and between 15 and 20% yield advantage over the six environments. The line mean repeatability for yield was moderate (0.492), with the variance component for line by environment (L x E) interaction 4.2 times that for lines. Therefore, while the CIMMYT lines expressed considerable L x E interaction, there was scope for further yield improvement. The water stress differential between the irrigated and dryland environments at the three locations strongly influenced L x E interaction for grain yield. Pre-anthesis water stress generated more L x E interaction for grain yield than post-anthesis stress. At the two locations where pre-anthesis water stress was severe in the dryland environment, there was no association (P > 0.05) between yield under irrigated and dryland conditions. However, at the location where there was little pre-anthesis stress and a degree of post-anthesis stress there was a strong association (P < 0.01) between yield under irrigated and dryland conditions. Grain yield was positively associated with the yield component grain number per unit area in all environments. Grain weight showed little L x E interaction across environments and the majority of L x E interaction for grain yield resulted from L x E interaction associated with grain number per unit area. Grain number per unit area was positively associated with the component grains per fertile tiller but not tiller number per unit area. Grains per fertile tiller was in turn positively associated with total dry matter at anthesis; however, there was no direct association between total dry matter at anthesis and grain number per unit area. There was a weak association between days to anthesis and grain yield in four of the six environments.


1991 ◽  
Vol 18 (1) ◽  
pp. 53 ◽  
Author(s):  
PC Pheloung ◽  
KHM Siddique

Field experiments were conducted in the eastern wheat belt of Western Australia in a dry year with and without irrigation (1987) and in a wet year (1988), comparing three cultivars of wheat differing in height and yield potential. The aim of the study was to determine the contribution of remobilisable stem dry matter to grain dry matter under different water regimes in old and modern wheats. Stem non-structural carbohydrate was labelled with 14C 1 day after anthesis and the activity and weight of this pool and the grain was measured at 2, 18 and 58 days after anthesis. Gutha and Kulin, modern tall and semi-dwarf cultivars respectively, yielded higher than Gamenya, a tall older cultivar in all conditions, but the percentage reduction in yield under water stress was greater for the modern cultivars (41, 34 and 23%). In the grain of Gamenya, the increase in 14C activity after the initial labelling was highest under water stress. Generally, loss of 14C activity from the non-structural stem dry matter was less than the increase in grain activity under water stress but similar to or greater than grain activity increase under well watered conditions. Averaged over environments and cultivars, non-structural dry matter stored in the stem contributed at least 20% of the grain dry matter.


1975 ◽  
Vol 26 (3) ◽  
pp. 497 ◽  
Author(s):  
EAN Greenwood ◽  
P Farrington ◽  
JD Beresford

The time course of development of a lupin crop was studied at Bakers Hill, Western Australia. The aim was to gain insight into the crop factors influencing yield. Weekly measurements were made of numbers and weights of plant parts, and profiles of roots, leaf area and light interception. A profile of carbon dioxide in the crop atmosphere was taken at the time of maximum leaf area, and the net carbon dioxide exchange (NCE) of pods was estimated for three successive weeks. The crop took 10 weeks to attain a leaf area index (LAI) of 1 and a further 9 weeks to reach a maximum LAI of 3.75, at which time only 33% of daylight reached the pods on the main axis. Once the maximum LAI was attained at week 19, leaf fall accelerated and rapid grain filling commenced almost simultaneously on all of the three orders of axes which had formed pods. Measurements of NCE between pods on the main axis and the air suggest that the assimilation of external carbon dioxide by the pods contributed little to grain filling. Grain dry weight was 2100 kg ha-1 of which 30%, 60% and 10% came from the main axis, first and second order apical axes respectively. Only 23% of the flowers set pods and this constitutes an important physiological limitation to grain yield.


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