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Soil constraints are a major limitation to grain production on waterlogging-prone sodic soils in the medium-rainfall zone of southern Australia, and several options have been proposed to overcome these constraints. A field experiment commenced in 1999 to compare the effectiveness of different management strategies, including improved crop nutrition, soil amelioration by using gypsum with or without deep ripping, applying organic matter, using raised beds or delayed sowing on improving the growth and grain yields of four consecutive crops including wheat (Triticum aestivum) in 1999 and 2002, barley (Hordeum vulgare) in 2000, and faba beans (Vicia faba) in 2001. Improving crop nutrition alone generally did not significantly improve grain yields, whereas adding ameliorants such as composted pig bedding–litter or deep ripping+gypsum produced grain yield increases in all crops by up to 48% compared with the control. Similar increases in grain yields were produced when crops were grown on raised beds, even in seasons when growing-season rainfall was well below average. Greatest yield increases were recorded when both raised beds and ameliorants were used (up to 2t/ha, or 63%). Spring-sown crops consistently produced lower grain yields than the (autumn-sown) control. For the three cereal crops (two wheat and one barley), increases in grain yields resulting from soil amelioration generally were not associated with increased harvest index or kernel size but were associated with greater tiller number and number of grains per m2. For the pulse crop, faba beans, yield increases were associated with greater dry matter production and increased number of grains per m2. All management strategies significantly increased crop nitrogen (N) uptake, although this did not necessarily translate to increased grain protein because of a dilution effect in the highest yielding treatments. Increases in grain yield coincided with improved root growth throughout the profile (up to 140cm depth). All physical amelioration treatments either reduced the degree of temporary waterlogging, as indicated by shallow piezometers, or improved soil structure, as indicated by reduced cone penetrometer resistance, compared with the control. Reduction in soil exchangeable sodium percentage on this highly sodic clay soil, measured within the first season after implementation, was less clear-cut. Increases in grain yield, however, appeared related to improved N supply rather than greater water use. Large increases in grain yields across a range of seasonal conditions appear possible on these soil types in medium-rainfall environments provided both soil structure and nutrition are improved.

Canola-quality Brassica juncea is a potential alternative crop species in lower rainfall Australian environments due to its superior heat and drought tolerance, disease resistance, and pod-shatter resistance compared with the currently grown B. napus species. Canola-quality types of B. juncea that are adapted to flower and mature before water deficits and high temperatures significantly limit yield potential are currently being developed. In this study, the variability in phenological characteristics in canola-quality B. juncea is assessed, with a view to identifying the potential for including a range of genetic phenological controls on the development of the crop to assist with adaptation.Vernalisation response was compared among 17 lines of B. juncea and 3 of B. napus, using a cold treatment of 2.6°C for 25 days. Leaf number, and duration to first flower and maturity were compared in response to the vernalisation treatments. To assess day length response, the same 20 genotypes were sown at five locations with a range of sowing times, and one controlled environment, where day length was artificially extended. Development stages were assessed and the duration of particular phenological phases determined in relation to time, thermal time, and photoperiod.The major factor controlling flowering in canola-quality B. juncea genotypes was day length, with only small responses to vernalisation detected. There was sufficient variability in these traits and in thermal time to flowering under long days (intrinsic earliness) within the current canola-quality germplasm in Australia to select early flowering genotypes with potential adaptation to low-rainfall environments.

The distribution of nitrogen in culms, leaves, chaff and grain at maturity was examined in eight semi-dwarf wheat (Triticum aestivumL) cultivars differing in culm length and maturity, and grown under both low and high nitrogen. There were significant differences between cultivars in days to anthesis and culm length but these were not influenced by the nitrogen treatment. The length of the culm was strongly correlated with the above-ground biomass in both nitrogen treatments (r = 0.52, low nitrogen; r = 0.74, high nitrogen), while the correlations between the length of the culm and plant nitrogen accumulation, total grain weight and total grain nitrogen content, were weaker in both nitrogen treatments with correlation values ranging from r = 0.31 to r = 0.39. In the low nitrogen treatment, nitrogen harvest index increased as the length of the culm increased but it was the reverse under the high nitrogen treatment. The length of the culm was not correlated with grain nitrogen percentage. The correlations between the primary and secondary tillers were positive and moderately high for the nitrogen concentration of grain, culms and leaves, but the correlation was lower for chaff. Mean grain weight and mean nitrogen content per grain from both tiller sources were not substantially different between primary and secondary tillers but values were generally higher for grains from the primary tiller.

The duration of the basic vegetative phase (measured as the time from transplanting to awn appearance and final number of leaves after four weeks cold treatment at 4°C and growth under an 18 h photoperiod) was determined for the barley cultivars Galleon and Parwan on four, and Schooner on three occasions with different mean temperatures during each experiment. The length of the basic vegetative phase decreased as the mean temperature increased although the ranking between the three cultivars remained consistent. The final number of leaves for each cultivar, however, was not influenced by mean temperature; ie, it was a more intrinsic character than time to awn appearance. A measure of basic vegetative phase, therefore, should always include a record of the final number of leaves on the main culm. Seedlings of the cultivars Galleon and Parwan (which vary for basic vegetative phase and photoperiod response) were interchanged between a short (normal daylength) and a long (normal daylength extended to 18 h) photoperiod at various times up to 22 days after seedling emergence. This technique was used to determine the length of time after seedling emergence that the plants are insensitive to photoperiod. The results showed that the duration of the photoperiod insensitive phase lasted for six to eight days for Galleon and 18 to 22 days for Parwan. Flower initiation, which coincides with the initiation of the final leaf, started between 10 and 12 days for Galleon and at or after 22 days for Parwan. These data suggest that the duration of the photoperiod insensitive phase is associated with the length of the basic vegetative phase and ends sometime before the start of flower initiation.

Plant nitrogen relationships were studied in 10 wheat cultivars sown at 3 sites (Horsham, Boort and Walpeup) in north-western Victoria by determining the nitrogen concentration and nitrogen content of plant components at anthesis and maturity. While the concentration of nitrogen varied in different plant components, whole plants at anthesis had a nitrogen concentration below the value required for maximum growth. The time to anthesis had an influence only on grain yield and grain nitrogen percentage at Horsham. Total assimilation of nitrogen at both anthesis and maturity was more strongly correlated to plant dry matter than plant nitrogen concentration. There was a significant negative correlation between grain nitrogen percentage and both nitrogen harvest index and harvest index. Grain yield was strongly correlated with total nitrogen accumulated at anthesis and more strongly correlated with total nitrogen accumulated at maturity. Grain yield was significantly correlated with nitrogen harvest index and more strongly correlated with harvest index. Grain yield was negatively correlated with grain nitrogen percentage. The negative association between grain nitrogen percentage and harvest index has important implications for the breeding of wheat with higher grain nitrogen percentage while maintaining or increasing grain yield. The results indicated that none of the measured parameters could be used for indirect selection aimed at improving grain nitrogen percentage.

Polyethylene glycol (PEG)-bound poly-l-leucine acts as a THF-soluble catalyst for the Juliá−Colonna asymmetric epoxidation of enones. Excellent enantioselectivities may be obtained even with short chain length polyleucine. FT-IR investigations have determined that the catalytically active polyleucine components of these copolymers have an α-helical structure.

Time to awn emergence and leaf number on the main culm were recorded for 10 barley cultivars grown under a short and long photoperiod after 4 weeks cold treatment at 4°C; the appearance of leaves on the main stem was also recorded at regular intervals. There were differences among the cultivars for photoperiod response and the duration of the basic vegetative phase. Photoperiod response tended to be complementary with basic vegetative phase, as one increased the other decreased and vice versa.Leaf appearance generally did not differ significantly between photoperiod treatments. In the short day, leaf appearance continued for a longer period with more leaves produced on the main stem. Leaf appearance as a function of time was best described by a cubic or a quadratic exponential polynomial function. The absolute rate of leaf appearance (leaves d-1) under short day showed an increase to a maximum followed by a decrease to a minimum and then a further increase. Under long day, three patterns of absolute rate of leaf appearance were evident. There was a rapid increase to a maximum followed by either a rapid or more gradual decline; in several cultivars the pattern was similar to the one seen for the cultivars in the short day treatment, although it was somewhat truncated. The significance of photoperiod response and basic vegetative phase are discussed in relation to crop adaptation and the change in the absolute rate of leaf appearance is discussed in relation to the stage of plant development.

By taking into account the peculiar structure of a-C(:H) thin films and, in particular, the tendencies of C-sp2atoms to cluster, we have developed, by modifying one of the current assumptions of the Hückel model for molecular orbitals (namely the negligible effect of the overlap between nearest neighbours atomic orbitals), a model able to describe the density-of-states of a-C(:H) films. It is shown that the bonding (‘valence’) and anti-bonding (‘conduction’) π-bands have asymmetric shapes. The imaginary part of the dielectric constant is evaluated on the basis of such model, by considering as well the role of many-body effects. The model properly describes the optical properties of a large set of different a-C(:H) films.

Two “S-type” (pelitic) granite suites from the New England Batholith, N.S.W., have Upper Carboniferous ages, indicating that they predate by 40 m.y. the intrusion of hornblende biotite granites, and are the oldest plutons of the batholith. Mineralogically and geochemically both suites have “pelitic” characteristics, one suite containing an Al-rich biotite, muscovite and cordierite, the other an Al-rich biotite and rare pyrope-almandine garnet. Low initial 87Sr/86Sr ratios of 0.706 for both suites probably reflect the volcanoclastic nature and young age of the sedimentary source of these granites at the time of melting. The age of the suites coincides with the last stages of (Andean type?) volcanism along an andesite/dacite volcanic chain to the west, suggesting an origin for the “S-type” granitic magma by partial melting of deformed sediments marginal to a continental region.

Oxygen and hydrogen isotope studies of a number of granite suites and mineral separates from the New England Batholith indicate that dO18 can be used to discriminate the major granite protoliths. The granite suites previously subdivided on the basis of mineralogical and geochemical criteria into S-type (sedimentary) and I-type (igneous) have dO18 values consistently higher in the S-type granites (10.4–12.5) than in the spatially related I-type plutons (7.7–9.9). There appears to be a systematic variation in dO18 from the most S-type to the most I-type granites, the dividing point between the two occuring at dO18 equal to 10. A group of leucocratic granites that form about half of the batholith and difficult to classify mineralogically and geochemically is found to have low dO18 values (6.4–8.1), suggesting an affinity to the most I-type granites. A single leucogranite pluton with minor muscovite has a dO18 of 9.6 which is significantly higher than other leucogranites indicating a different origin perhaps involving amphibole fractionation.

Bodies of pyroxene-bearing rhyodacite in New England, New South Wales, previously considered to be intrusions, are reinterpreted as ignimbritic flows. Small aggregates of pyroxene and plagioclase are inferred to be either compositionally modified crystalline residuals from partial melting or crystal cumulates. An earlier hypothesis involving mixing of solid biotite-diorite with a rhyolitic liquid is questionable, and the origin of the rhyodacite can be explained in terms of recent experimental work on crystal-liquid equilibria under inferred crustal conditions.

Microstructural criteria distinguish two types of fibrolitic sillimanite-bearing aggregates, namely: (1) those with fibrolitic sillimanite in clear microstructural equilibrium with the other minerals, and (2) those with fibrolitic sillimanite that appears to have grown without evident modification of pre-existing grain boundaries of the other minerals. However, microstructural criteria rarely permit unambiguous inferences of the relative “timing” of metamorphic reactions producing fibrolitic sillimanite.

This is the first exposition of a new methodology (or perhaps meta-methodology) for systems practice known as Total Systems Intervention (TSI). Designed to overcome the weaknesses of hard, cybernetic, and soft systems approaches and build on their strengths, TSI represents a practical face of critical systems thinking. It advocates combining three building blocks-systems metaphors, “system of systems methodologies,” and individual systems methodologies—in an interactive manner which is deemed to be particularly powerful and fruitful. In this paper the philosophy, principles, and phases of the TSI methodology are set out and two very different examples of its use are provided.

The influence of vernalization on days to ear emergence in hexaploid wheat (Triticum aestivumL. em. Thell.) was examined in five Chinese Spring/Thatcher (CS/T) chromosome substitution lines. CS/T 5A and 5D were similar to normal Chinese Spring in days to ear emergence after all periods of vernalization while CS/T 3B and 5B were similar after some, but significantly earlier after other periods of vernalization When compared with Chinese Spring. In both the unvernalized condition and when vernalization did not limit development rate CS/T 7B was faster to ear emergence than Chinese Spring. These results are discussed in relation to the known chromosomal and genetical control of vernalization response.

Variation for high molecular weight (HMW) glutenin subunits is reported in Afghan hexaploid wheat landraces from different locations in the country ranging in altitude from 395 to 3170 metres. The variation appeared to be independent of the altitude and geographical location of the landraces. Studies of a number of samples from each of five sites revealed that at some sites there was allelic variation at theGlu-A1 andGlu-B1 loci coding from HMW glutenin subunits, but there was no variation at theGlu-D1 locus within and between sites.

Studies were made of days to ear emergence under the constant temperatures of 9, 14, 19 and 25°C and 16 h photoperiod in three sets of wheat lines each possessing genotypes differing for developmental responses.

Eclogite of high-pressure low-temperature origin occurs within the Great Serpentine belt of New South Wales. The presence of glaucophane-bearing rocks and other medium to high-pressure assemblages associated with the belt is similar in many respects to the Californian and Oregon occurrences. The chemical composition of the eclogite is characterized by low K2O values comparable to many oceanic tholeiites, although one analysis is nepheline-normative. Ti-Zr-Y ratios also show affinities to ocean-floor basalts.The garnet contains approximately 30% grossular and is strongly zoned from almandine (Alm 56%, Py 9%) at the core towards pyrope (Alm 44%, Py 27%) at the margin. Sodic augite contains 30-33% Jd, 4-7% Ac, and 72-74% Di+He.Distribution of Fe and Mg between co-existing garnet and pyroxene would suggest an increasing temperature during eclogite crystallization with a possible range from 290°C to 600°C and a minimum pressure of 7-12 kb.

In this paper six scenarios for the future of systems “problem solving” are investigated in order to ascertain whether an approach can be identified (a) that offers prospects for the long-term survival and success of systems problem solving in practice and (b) that does this without incorporating theoretical contradictions. The six approaches come under the four class headings pragmatism, isolationism, imperialism, and pluralism. The theoretical foundations of each approach are explored in a discursive fashion. This makes explicit to systems practitioners the underlying principles on which their activities are overlaid and puts such approaches into the theoretical context of the six approaches identified herein.

There have been a number of reports indicating that, in the absence of vernalization and photoperiod influences, there is a factor(s) which acts to exert control over the rate of development in bread wheat (Triticum aestivumL. em. Thell.). In an attempt to characterize this phenomenon more fully, three sets of wheat genotypes were examined for their rate of development in the absence of vernalization and/or photoperiod influences. Seventeen spring wheats, prevernalized and grown with an 18‐h photoperiod in an outdoor pot experiment were found to differ in development rate, indicating that it may be of significance to adaptability and yield, at least in this type of wheat. In a set of near‐isogenic lines of ‘Triple Dirk’ (differing for the vernalization response genes vrn 1and vrn 2) their development rates were similar, indicating that it is not a manifestation of the action of genes for vernalization response. Additionally, the absence of a close correlation between the level of vernalization response and basic development rate in the 17 spring wheats indicates physiological independence between the two processes. Using growth apex dissection the various phases of floral development were followed in two Australian spring wheat cvs., Pinnacle and Falcon, at four times of sowing in an outdoor situation and grown under an 18‐h photoperiod. The cv. Falcon was much faster than Pinnacle from sowing to floral initiation, terminal spikelet, and ear emergence at the four times of sowing. While the vegetative phase in Pinnacle was generally longer than in Falcon, the spikelet initiation and stem elongation phases did not show the same relative prolongation. ‘Chinese Spring’/‘Thatcher’ chromosome substitution lines 7B and SD, pre‐vernalized for weekly periods from 0 to 8 weeks and grown with an 18‐h photoperiod in an outdoor pot experiment were used to investigate the chromosomal control of development rate in wheat. Chromosome 7B of Thatcher substituted in Chinese Spring reduced its vernalization requirement and increased its rate of development. Chromosome 5D of Thatcher did not alter either vernalization response or rate of development of Chinese Spring. In view of these data and earlier reports, the term “basic development rate” is proposed to denote differences between wheats in the rate of development in the absence of vernalization and photoperiod influences. Recognition of the phenomenon of basic development rate prompts a re‐evaluation of the developmental basis of flowering in wheat and other temperate plants.

In the random field approach to lattice gas models it has been shown that the one point conditional probabilities determine the finite set conditional probabilities under conditions of strict positivity and regularity. This paper considers the case when strict positivity does not obtain with families of conditional probabilities more general than the one-point conditional probabilities.

In this paper we are concerned to overcome the impoverished use of analogy (and metaphor) to be found in the early days of explicit general systems thinking and modern day interpretive systems thinking. Our aim is to focus on the fundamental methodological principles of analogical reasoning and to reconsider the utility of such thought for systems sciences in terms of systemic dialectics.

Petrological, isotopic, and gravity data for a massive granodiorite with K-rich biotite-diorite and tonalite variants in the New England Batholith, Australia, indicate that the more mafic rock types form the lower parts of a pluton that has been tilted so as to expose the base along its southwestern margin. The mafic rocks are inferred to be cumulates of refractory and phenocrystal phases and not the products of independent K-rich basic magmas. This evidence of tilting in the unfoliated granodiorite Uralla pluton suggests that granite samples should be used cautiously in palaeomagnetic-palaeolatitude studies, for the absence of metamorphic foliation is not sufficient evidence that the granite has not been tilted.

A suite of cordierite-bearing biotite-muscovite intrusive granites in the New England Batholith, New South Wales, outcrops over 3400 sq km and is the largest reported occurrence of granites of this type. Compositionally the granites are close to the low temperature minimum and display only limited chemical variation. The corundum-normative nature of the granites suggests a pelitic sedimentary parentage. Cordierite with an average 100 Mg/ Mg + Fe of 55 occurs as large tabular crystals and is considered to be a refractory phase brought up from the zone of partial melting. The presence of cordierite and the absence of garnet in these granites suggests a partial melting at a pressure maximum of 6 kb, equivalent to 22 km depth.

New data for the Wologorong Batholith, northwest of Goulburn, New South Wales, indicate that it is S-type and probably similar in age to the major batholith in the southern part of the Lachlan Fold Belt. Its component rocks are predominantly biotite and biotite-muscovite adamellite, and have a strong N-S metamorphic foliation. An isochron, defined by fourteen rocks, gives a Rb/Sr age of 405 ±11 Ma and an initial 87Sr/86Sr ratio of 0.7110 ± 0.0012. Five Rb/Sr biotite ages range between 339 and 381 Ma, the older ages being obtained from the least deformed parts of the Batholith. Whereas uncertainties inherent in dating a deformed S-type batholith make 405 Ma a reconnaissance value only, the minimum emplacement age for the Batholith, as determined from two biotites, is around 381 Ma. The younger biotite ages, around 339 to 348 Ma, are considered to date a major period of regional metamorphism in the northeastern part of the Lachlan Fold Belt, similar to that recorded from K/Ar ages of metamorphic biotite in the Hill End region 100 km to the north.The I-S line of Siluro-Devonian granites, defined in the southern part of the Lachlan Fold Belt, extends in a NNE direction, and passes to the east of the Wologorong Batholith. To the north of the Carboniferous Bathurst, the position of the line is uncertain, because of the absence of Siluro-Devonian S-type granites, and establishing its presence may depend on the nature of the volcanic rocks, as yet not investigated.

Woodlark Island, the largest above-sea portion of the Woodlark Rise, has an exposed basement of pre-Miocene (?Cretaceous-Eocene) low-K tholeiitic basalt and dolerite, and minor sediments. The basement is unconformably overlain by Early Miocene limestone and volcaniclastic sediments and later Miocene high-K volcanics and comagmatic intrusives. Pleistocene to Recent sediments partly blanket the Tertiary sequence. Basement low-K tholeiites vary only slightly in composition and are interpreted as ocean floor or possible marginal basin material. The high-K suite appears to be chemically similar to late Tertiary to Recent high-K igneous rocks of mainland Papua New Guinea. It includes porphyritic hornblende-, clinopyroxene-, biotite- and magnetite-bearing shoshonite, latite and toscanite, and intrusive equivalents that range from olivine normative to strongly quartz normative compositions (S1Q2 46% to 75%). Computer mixing models indicate that separation of the pheno-crysts in the shoshonites, particularly pargasitic hornblende, is a feasible mechanism for producing the more silica-rich monzonites and latites.The low-K tholeiitic basement rocks of Woodlark Island are inferred to be part of an ophiolitic slab en echelon with the Papuan Ultramafic Belt, thrust over equivalents of the Cretaceous Owen Stanley Metamorphics or, in part, onto existing oceanic crust. High-K igneous rocks on Woodlark Island appear to form an eastward extension of a province of calcalkaline to shoshonitic volcanic and intrusive rocks, which stretches from Mount Lamington to the Louisiade Archipelago. Late-middle Miocene high-K magmatism at Woodlark Island is consistent with the observation that activity commenced earlier in the E and became progressively younger westwards towards mainland Papua New Guinea. Periodicity in the magmatism was apparently synchronous with major rifting episodes that formed the Woodlark Basin. The data on the Woodlark Island high-K suite support the currently accepted. concept of delayed partial melting of a mantle source previously modified by the introduction of water and LILE from an earlier subduction zone (Johnson et al., 1978b).

Ultramafic hornfelses containing the assemblages hornblende + olivine + spinel + magnetite, and clinopyroxene + olivine + spinel + magnetite, are reported from two localities in the Biggenden Beds in southeastern Queensland. They are associated with mafic hornfelses in the contact metamorphic aureoles of the Mungore Adamellite and the Wateranga Gabbro. Chemical composition and minerology of the olivine + amphibole + spinel + magnetite hornfelses suggest that they represent metamorphosed picritic rocks, or possibly, altered serpentinites (blackwall rocks), whereas the clinopyroxene + olivine + spinel + magnetite hornfelses are interpreted as metamorphosed altered clinopyroxene-rich picritic rocks. Cr-Fe spinel relations in the hornfelses indicate partial homogenisation of primary chromian spinel with secondary magnetite ± ferrichromite during contact metamorphism.

Systems and cybernetic methodology have traditionally drawn upon the concepts of analogy and metaphor. These are, however, contentious on both philosophical and practical grounds. The work we present in this paper mostly aims to overcome the philosophical difficulties by uncovering the basic principles of analogic modeling and by showing how these can complement inductive and deductive reasoning. Analogy and metaphor are then shown to be complementary and can be considered to be on one spectrum, from creative metaphor to the more formal approach of analogy. Contention on practical grounds is allayed as the role of analogy and metaphor in systems and cybernetic methodology is outlined.

This paper seeks to open up debate between organization theorists and cyberneticians on the basis or commonalities of concern and similarities in the recommendations made to managers. Stafford Beer's "viable system model" is put forward as a framework which can be employed to integrate the findings of these two disciplines into a practical management tool. The VSM itself, as an exalted expression of the organization theory/cybernetic orthodoxy, is then "put on trial," with a view to drawing conclusions about the relevance and value to managers of this type of thinking.

The Ben Bullen plutons constitute a small medium-K gabbro-tonalite-trondhjemite suite spatially and temporally associated with extensive adamellite and granite of the Bathurst Batholith. The mafic composition of the bulk of the Ben Bullen rocks suggests a mantles source for the parent magma. Chemical and petrographic studies indicate that the rocks are closely comparable with medium-K calc-alkaline volcanic suites in island arcs. The Ben Bullen series are M-type granites in the sense of being formed by crystal fractionation of a gabbroic parental magma. Initial crystallization and separation of olivine and pyroxene followed by marked fractionation of hornblende probably drove the differentiating magma along a typical calc-alkaline trend of strong alkali-enrichment. It is possible that the rise of these mantle-derived melts into the crust initiated the crustal melting that produced the associated felsic K-rich granitoids of the Bathurst Batholith.

The first of 2 studies reported in this paper investigated the variation in 15 barley genotypes for the durations of 3 periods of pre-anthesis development [leaf initiation (LI), spikelet initiation (SI), and spikelet growth (SG) phases], and the degree of independence of the duration of the SG phase from each of the LI and SI phases. There were differences between genotypes in the duration of the SI and SG phases which were not closely correlated (r = – 0·58, P < 0·05) across genotypes, indicating the feasibility of genetically combining different durations of the 2 phases while maintaining a constant time to anthesis. The duration of the LI phase was closely correlated with time to anthesis (r = 0·82, P < 0·001) but not with the duration of either the SI or SG phase. The rate and duration of spikelet initiation were negatively correlated across genotypes (r = – 0·75, P < 0·01). There was little variation in the number of spikelet primordia formed over the range of genotypes but there was considerable variation in the number of aborted spikelet primordia. The study indicated the likelihood that in breeding to increase the yield potential of the spike in barley, there is more potential for reducing the level of spikelet primordia abortion during the SG phase than increasing the number of spikelet primordia per spike. The second study investigated whether 3 photoperiod regimes (15·5, 14, and 12–13 h), imposed for the duration of the LI and SI phase, had any subsequent effect on the duration of the SG phase in 2 cultivars, Bandulla and Galleon. There were no major effects, suggesting that the duration of the SG phase was largely independent of the duration of the 2 previous phases. Additional keywords: spikelet initiation, spikelet abortion, yield potential.

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