Genotypic variation in osmotic adjustment in grain sorghum. II. Relation with some growth attributes

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.

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.


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.


1996 ◽  
Vol 47 (5) ◽  
pp. 757 ◽  
Author(s):  
JH Mitchell ◽  
S Fukai ◽  
M Cooper

We investigated the influence of sowing time and genotypic variation for phenology on grain yield of barley in south-eastern Queensland. Over 3 seasons, 8 trials with 10 cultivars and 1 trial with 4 cultivars were conducted under either irrigated or terminal drought conditions at 2 locations. Rainout shelters ensured the development of severe terminal water stress. Trials were either sown on a common date, as conducted in traditional multi-environment trials, or over 3 weeks to synchronise anthesis among cultivars of different phenologies. Within the common sowing date trials, variation (P < 0.01) existed among cultivars for grain yield. From the 6 common sowing trials there was a negative correlation (P < 0.05) between grain yield and days to anthesis; that is, the shorter duration cultivars expressed the highest grain yield. Variation in days to anthesis accounted for 48-72% of the variation for grain yield. In the staggered sowing trials, where anthesis of all cultivars occurred within 4 or 2 days of the mean anthesis date, variation for grain yield was small or non-significant, and there was no association between grain yield and days to anthesis. The staggered sowing experiment with 10 cultivars indicated that duration of the vegetative phase was important in determining total dry matter production at maturity when cultivars were grown under terminal drought. Long-duration cultivars sown earlier had greater total dry matter at maturity than short-duration cultivars. This was associated with a greater water extraction by the long-duration cultivars, especially at depth, which remained inaccessible to later sown, short-duration cultivars. However, due to the low harvest index of the long-duration cultivars, grain yield of long- and short-duration cultivars was comparable when anthesis of cultivars was synchronised. When sown at the same time, a short-duration cultivar is advantageous because of a high chance of escaping water stress that develops during the critical development stage of anthesis. The results from the staggered sowing date experiments, however, indicated that the long-duration cultivars, when sown earlier in the season, had no yield disadvantage in comparison with the short-duration cultivars sown later in the season. Therefore, there is scope to develop barley cultivars of later phenology than is currently available to provide Queensland farmers with the option of utilising early rainfall events which are sometimes the only planting opportunity.


1994 ◽  
Vol 45 (5) ◽  
pp. 985 ◽  
Author(s):  
M Cooper ◽  
DE Byth ◽  
DR Woodruff

The objective of this study was to use classification methodology to characterize the genotypic variation and line by environment (L x E) interaction for grain yield of a sample of advanced CIMMYT wheat lines and three local check cultivars tested over six Queensland environments. The environments were managed to differ in the magnitude of water stress they imposed on the lines at the critical developmental stage of anthesis. The grouping of lines was based on grain yield. The yield differences among the groups were investigated in terms of yield components and dry matter production and partitioning attributes. Groups of CIMMYT lines which outyielded the two groups which contained the three Queensland cultivars were identified. The yield advantage of the groups of CIMMYT lines decreased with increasing severity of water stress at anthesis and in the environment where the most severe stress was characterized there were no yield differences among the groups of lines. The yield advantage of the groups of CIMMYT lines was generally associated with a higher number of grains per unit area and in some cases a higher grain size. While phenology variation could account for some of the yield differences among the line groups there was considerable yield variation among line groups with similar phenology patterns across the environments. Additional measurements taken on the lines to characterize differences in dry matter production and the partitioning of the dry matter to yield components were not effective in explaining the yield variation among the groups of lines after the effects of phenology were taken into account. While the incidence of the large L x (water-stress) interactions encountered in this study would complicate selection for yield, the identification of groups of advanced CIMMYT lines which outyielded the Queensland cultivars in five of the six environments suggests that the L x (water stress) interactions do not preclude scope for further improvement of grain yield of wheat in Queensland.


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.


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.


1984 ◽  
Vol 35 (1) ◽  
pp. 1 ◽  
Author(s):  
GS Gill ◽  
WM Blacklow

A field experiment was conducted at Badgingarra, W.A., during 1981 to study competition between wheat (cv. Gamenya) and great brome (Bromus diandrus Roth.). Shoot dry matter per plant of wheat was reduced from 1.41 g per plant in wheat monoculture to 0.50 g per plant after competing for 71 days with great brome at density of 400 plants m-2. Tiller production was reduced from 605 tillers m-2 in monocultures of wheat to 336 tillers m-2 when growing in association with 400 plants m-2 of great brome. Competition with great brome reduced the concentration of nitrogen and phosphorus in wheat shoots; at Feeke's scale 3 (tillers formed) wheat plants competing with 400 plants m-2 of great brome had 3.15 � 0.09% (mean � s.e., w/w) nitrogen and 0.58% phosphorus against a concentration of 4.05 � 0.1% nitrogen and 0.77% phosphorus in the monoculture of wheat. The reduction in the nitrogen - and phosphorus concentrations in wheat shoots earlier than any significant reductions in their dry matter suggested that great brome competed with wheat for absorption of nitrogen and phosphorus. Competition with great brome also resulted in significant reduction in the grain yield (r = - 0.77) and yield determinants of wheat. Reduction in mass per grain (r = - 0.77) was probably due to competition with great brome for water during grain-filling.


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.


1987 ◽  
Vol 14 (6) ◽  
pp. 669 ◽  
Author(s):  
BP Naidu ◽  
GP Jones ◽  
LG Paleg ◽  
A Poljakoff-Mayber

Fifteen species of Melaleuca and two species of Callistemon from the field were examined to determine whether they accumulated nitrogen-containing compatible solutes and, if so, which. In addition to L-proline, N-methyl-L-proline (MP) (isolated for the first time from plants), trans-4-hydroxy-N-methyl- L-proline (MHP), and N, N'-dimethyl-trans-4-hydroxy-L-proline (DHP) were found in various combinations in the 15 Melaleuca species. M. lanceolata seedlings were subjected to water or salinity stress and M. uncinata to water stress under laboratory conditions. In both species significant reductions in leaf water potential (Ψw), osmotic potential (Ψs), turgor potential (Ψp), and relative water content (RWC) were observed in response to water stress. Salinised M. lanceolata plants showed considerable osmotic adjustment and maintained Ψp comparable to that of control plants; salinity, however, decreased RWC. In response to the imposed stresses under laboratory conditions, proline and MHP levels in M. lanceolata, and MHP and DHP levels in M. uncinata, increased. In addition to possible protective or osmotic roles in vivo, these proline analogues may be useful in chemotaxonomic investigations of Melaleuca species.


1995 ◽  
Vol 35 (4) ◽  
pp. 495 ◽  
Author(s):  
RG Flood ◽  
PJ Martin ◽  
WK Gardner

Total crop dry matter (DM) production and its components, remobilisation of stem reserves, and the relation of these to grain yield were studied in 10 wheat cultivars sown at Walpeup, Boort, and Horsham in the north-western Victorian wheatbelt. Between sites, all DM components decreased in the order Horsham > Boort > Walpeup. Differences between Boort and Walpeup were not always significant. Total DM at anthesis for Walpeu,p and Boort was in a similar range, and less than that for Horsham. Yields increased in the order Walpeup < Boort < Horsham. When data from the 3 sites were combined, leaf, stem (excluding cv. Argentine IX), and total DM were related to grain yield. Within sites, ear DM at anthesis was related to grain yield. Grain yield for all cultivars at Horsham and Walpeup and 5 cultivars at Boort was greater than the increases in crop DM from anthesis to maturity, indicating that pre-anthesis stored assimilates (stem reserves) were used for grain filling. Post-anthesis decrease in stem weight was inversely related to grain yield only at Horsham, which supports the view of utilisation of stem reserves for grain filling at this site. At Boort and Walpeup there was a similar negative trend, but values for 2 cultivars at each site were outliers, which weakened the trend. The wide adaptability of the Australian cultivars used in this study may be related to the differential remobilisation of stem reserves at each site. A measure of yield stability, however, was not related to stem weight loss during the grain-filling period.


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