Accessions totalling 1425 from the Australian Lupin Collection representing 9 Old World lupin species and Lupinus mutabilis Sweet, a New World species, were sampled for seed coat and pod wall percentage, seed weight, and number of seeds per pod. These traits are of importance to the breeding objective of lowering seed coat and pod wall proportions in crop lupins. Seed coat percentage mean values among the species ranged from 12.7 in L. mutabilis to 33.7 in L. pilosus L. The 4 species that have been subject to selection (L. mutabilis, L. albus L., L. angustifolius L., and L. luteus L.) had lower mean seed coat percentages than the other species with little domestication. The rough-seeded lupin species had higher seed coat percentages relative to the smooth-seeded species except for L. micranthus Guss., which had 31.5% seed coat and small seeds. Within L. angustifolius there was no difference between the mean seed coat percentage values for wild v. domesticated or hard v. soft-seeded entries, although wild accessions of L. angustifolius tended to have lower seed weight, higher pod wall percentage, and more seeds per pod than domesticated accessions. There was no correlation in L. angustifolius germplasm between seed coat percentage and pod wall percentage, indicating that selection for one will not influence the other character. Accessions with the lowest seed coat percentage were from Turkey, Greece, and Cyprus, and those with the lowest average pod wall percentage were from Spain and Cyprus. Mean pod wall percentages ranged from 30.9 in L. albus to 57.1 in L. micranthus; figures that are high compared with other legumes. Large ranges in seed weight were found particularly in L. albus, L. pilosus, and L. angustifolius. In addition to the germplasm collection, 21 Australian cultivars, released from 1967 to 1999, were evaluated at one site over 2 years for the same traits. There was a negative correlation between seed coat percentage and seed weight for both L. angustifolius historical cultivars and germplasm, indicating that further reductions in seed coat percentage could be achieved by crossing large seeded types with low seed coat types. Pod wall percentage was negatively correlated with both year of release and yield, and positively correlated with days to flowering. These data support other findings that breeding for the reduction of pod wall can lead to yield improvements. The germplasm collection assessed here provides lines with lower seed coat and pod wall compared with what is available in breeding lines or cultivars.

Simulation of narrow-leafed lupin (Lupinus angustifolius L.) production would be a useful tool for assessing agronomic and management options for the crop. This paper reports on the development and testing of a model of lupin development and growth, designed for use in the cropping systems simulator, APSIM (Agricultural Production Systems Simulator). Parameters describing leaf area expansion, phenology, radiation interception, biomass accumulation and partitioning, water use, and nitrogen accumulation were obtained from the literature or derived from field experiments. The model was developed and tested using data from experiments including different locations, cultivars, sowing dates, soil types, and water supplies. Flowering dates ranged from 71 to 109 days after sowing and were predicted by the model with a root mean square deviation (RMSD) of 4–5 days. Observed grain yields ranged from 0.5 to 2.7 t/ha and were simulated by the model with a RMSD of 0.5 t/ha. Simulation of a waterlogging effect on photosynthesis improved the model performance for leaf area index (LAI), biomass, and yield. The effect of variable rainfall in Western Australia and sowing date on yield was analysed using the model and historical weather data. Yield reductions were found with delay in sowing, particularly in water-limited environments. The model can be used for assessing some agronomic and management options and quantifying potential yields for specific locations, soil types, and sowing dates in Western Australia.

Yield variability in lupin due to variable rainfall and delay in sowing is a key constraint to lupin production in the agricultural region of Western Australia. A lupin simulation model has been developed using the APSIM legume template. Initial testing of the model for Western Australian conditions has shown good performance for phenology, shoot biomass and yield. The model was linked to long-term weather data to simulate yield for two soil types and two sowing decisions rules in a low and high rainfall location. Simulated yields were very variable and declined with delay in sowing. Simulated yields were higher on a loamy sand soil than on a sandy soil. The impact of seasonal variability and sowing decisions on lupin yields was quantified for different rainfall locations in Western Australia.

Most current cultivars of narrow-leafed lupin have an indeterminate growth habit such that vegetative growth continues while the pods are being filled, causing strong intra-plant competition for assimilates. Restricted-branching (RB) genotypes can reduce this tendency and raise the proportion of the plant's biomass going into grain. Studies on the inheritance of the RB trait showed that two spontaneous mutants, P25598 and P21227, each carried a single incompletely dominant allele conferring the trait, whereas two other spontaneous mutants, P24743 and P25582, and two induced mutants, P26021 and P21238, each carried a single recessive allele conferring the trait. The RB alleles present in P26021 and P21238 seem to be the same, and to be at the same locus as (or tightly linked to) the allele controlling the RB trait in P21227. Similarly, the genes present in P21227 and the induced mutant P25735 appear to be the same when these lines are crossed. However, they do not behave the same in crosses with P26021: thus we propose that there are at least three alleles at the same locus (or at tightly linked loci) that confer RB. Normal-branching plants that are heterozygous at an RB locus generally have fewer leaves on the uppermost branch than homozygous-normal plants. Similarly, RB plants that are heterozygous generally have fewer branchless nodes on the main stem than homozygous-RB plants. The RB trait is associated with a small but significant reduction in the number of leaves on the main stem. However, this relationship is weak and will not prevent plant breeders from selecting both early- and late-flowering RB genotypes.

Environmental and genetic effects on hull and pod wall proportions in lupin were examined by analysing data from 125 advanced genotypes at 17 year x site combinations in Western Australia. In Lupinus angustifolius the effect of genotype dominated the variance for seed hull and pod wall percentage and weight per seed, indicating strong heritability for these traits. Smaller but significant effects of site, and year x site and year x site x genotype interaction, were present for hull percentage, and year x site and year x site x genotype interaction effects were present for pod wall percentage. Hull percentage was found to be stable across branch orders within the plant canopy, but pod wall percentage increased and weight per seed decreased from main stem to higher branch orders. The average value of hull percentage was 24.0 in L. angustifolius with a range from 21.8 to 26.2%. L. albus (cv. Kiev Mutant) had a lower value than L. angustifolius at 18.1% and L. luteus cv. Wodjil gave a value of 24.5%. Hull percentage was found to decrease by approximately 0.5% for each 10 mg increase in seed weight. Hull thickness was found to correlate with site seasonal rainfall (r=0.45*). The correlation between genotype means for hull percentage and pod wall percentage was not significant for this set of breeding lines and cultivars, indicating that selection for one will have little effect on the other. A low but significant correlation was identified between hull percentage and protein percentage (r=-0.38**) and protein + oil percentage (r=-0.46**), showing that selection for lower hull proportion could lead to higher protein and oil concentration in seed. Pod wall percentage averaged 32.0% among L. angustifolius genotypes and was 28.1% in L. albus. At 41.7%, L. luteus had a very large proportion of dry matter in pod walls.Pod wall percentage was weakly negatively correlated with yield among 122 L. angustifolius genotypes (r=-0.19*). Pod wall percentage tended to increase with longer growing seasons. The results demonstrate the relatively narrow range in hull and pod wall percentage available in breeding lines and cultivars representing the current genetic base of Western Australian material but that the traits are highly heritable and selection is likely to be relatively easy. New sources with lower seed hull and pod wall proportions should be sought from wild and semi-domesticated germplasm or through mutagenesis to broaden the genetic base for these traits. The relationships between these traits and resistance to insects and disease are yet to be determined.

Establishment of restricted branching narrow-leafed lupins (Lupinus angustifolius L.) is often poorer than that of the normal branching counterparts. This study focused on establishment of the cultivars Tallerack and Merrit, as representative of restricted and normal branching lupins, respectively. Establishment from seeds of both genotypes harvested manually was high, but machine harvesting decreased establishment, at some sites markedly, and generally more so in Tallerack than in Merrit. Establishment problems were related to germination and not emergence or seedling vigour. A similar contrast was found when seeds were harvested from several near-isogenic pairs of restricted- and normal branching genotypes. The basis of the generally greater sensitivity of the restricted branching genotypes to harvest damage, and the interaction with environment is not clear. It is not related to differences between genotypes in the seed size, proportion of hull in seeds or seed moisture content, but hull composition and embryo morphology warrant further study. Irrespective of its basis, higher harvest damage to seeds of restricted branching genotypes is likely to be avoided by minimising harvester drum speeds and harvesting at higher seed moisture concentrations.

We studied the adaptation of narrow-leafed lupin (Lupinus angustifolius) and yellow lupin (L. luteus) to waterlogging because yellow lupin may have potential as a new legume crop for coarse-textured, acidic, waterlogging-prone areas in Western Australia. In a controlled environment, plants were waterlogged for 14 days at 28 or 56 days after sowing (DAS). Plants were more sensitive when waterlogged from 56 to 70 DAS than from 28 to 42 DAS, root growth was more sensitive than shoot growth, and leaf expansion was more sensitive than leaf dry weight accumulation. Waterlogging reduced the growth of narrow-leafed lupin (60–81%) more than that of yellow lupin (25–56%) and the response was more pronounced 2 weeks after waterlogging ceased than at the end of waterlogging. Waterlogging arrested net root growth in narrow-leafed lupin but not in yellow lupin, so that after 2 weeks of recovery the root dry weight of yellow lupin was the same as that of the control plants but in narrow-leafed lupin it was 62% less than the corresponding control plants. Both species produced equal amounts of hypocotyl root when waterlogged from 28 to 42 DAS but yellow lupin produced much greater amounts than narrow-leafed lupin when waterlogged from 56 to 70 DAS.

This study determined whether the tolerance of yellow lupin to waterlogging, observed in experiments in controlled environments, occurs under field conditions. Of particular interest is the impact of waterlogging on the distribution of roots because lupin is exposed to terminal drought in the south of Western Australia, which in itself can have a profound effect on yield. A field experiment was undertaken in the central grain-growing region of Western Australia near Beverley using hydraulically isolated plots to impose and remove waterlogging in a duplex soil. The responses of root and shoot growth of narrow-leafed and yellow lupin to waterlogging in the field were similar to those observed in the controlled environment experiments. In the field experiment, waterlogging had no effect on seed yield of yellow lupin but reduced it by 61% in narrow-leafed lupin. Waterlogging more than halved the dry weight of narrow-leafed lupin but reduced it by only 19% in yellow lupin. In yellow lupin, yield was 3.4 t/ha with waterlogging and 3.8 t/ha without waterlogging, compared with 1.4 t/ha with waterlogging and 3.5 t/ha without waterlogging in narrow-leafed lupin. Waterlogging had no effect on the harvest index of yellow lupin (0.26) but reduced it from 0.36 to 0.31 in narrow-leafed lupin. The larger effect of waterlogging on the yield of narrow-leafed lupin was mainly attributable to fewer pods.Net root growth ceased during waterlogging in both species. After waterlogging, roots of yellow lupin grew at a similar rate to the controls, whereas roots of narrow-leafed lupin grew at a much slower rate than the controls. Waterlogging halved the root density of yellow lupin at 25 cm depth and almost eliminated the roots of narrow-leafed lupin at this depth. After waterlogging, root production in the surface 10 cm increased to about 0.5 cm/cm(3) in yellow lupin but to 0.2 cm/cm(3) in narrow-leafed lupin. At depth (> 20 cm), roots of waterlogged yellow lupin continued to grow while those of waterlogged narrow-leafed lupin grew little, if at all. Yellow lupin tolerated waterlogging in the field better than narrow-leafed lupin because it re-established its root system at depth after waterlogging was removed and it produced more fertile pods.

Yellow lupin (Lupinus luteus) may have potential as a legume crop in waterlogging-prone areas of Western Australia. To elucidate the physiological response of yellow lupin and the widely grown narrow-leafed lupin (L. angustifolius) to transient waterlogging we conducted experiments in controlled environments. Narrow-leafed lupin and yellow lupin were grown in pots and waterlogged for 14 days from 28 to 42, or 56 to 70 days after sowing, each being followed by a 14-day recovery period. Root and shoot growth responses, leaf gas exchange, water relations, and N accumulation were assessed. During the period of waterlogging, net nitrogen accumulation ceased in both species at both ages. During recovery, yellow lupin accumulated more nitrogen than narrow-leafed lupin. Waterlogging reduced leaf gas exchange more with older plants than with younger plants, and more so with narrow-leafed lupin than yellow lupin. Some components of leaf gas exchange, particularly leaf conductance, were reduced by up to 80%. Waterlogging had no effect on leaf water potential of yellow lupin but reduced it in narrow-leafed lupin, from about –450 to –1100 kPa, especially during the recovery period. Yellow lupin was more adapted to transient waterlogging than narrow-leafed lupin because it maintained its leaf water status, it accumulated more nitrogen during recovery, and its photosynthetic activity recovered quickly afterremoval of waterlogging.

To understand how yellow lupin tolerates waterlogging better than narrow-leafed lupin, we investigated the roles of the roots and the shoots of these species. Reciprocal- and self-grafted combinations (scion = shoot/rootstock) of yellow and narrow-leafed lupin were made at the 2-leaf stage and waterlogged 45 days later (8–10 leaf stage). Responses to waterlogging were examined at the end of waterlogging and following a recovery period of 14 days.Waterlogging of reciprocal and self-grafted plants reduced total plant dry weight by 15–58% compared with non-waterlogged controls. These reductions were greater when the rootstock was narrow-leafed rather than yellow lupin, and were similar for the roots and shoots. Waterlogging increased dry weight of hypocotyl roots in most grafting combinations (by 2–19-fold), but grafts with narrow-leafed lupin scions produced almost twice the hypocotyl root length of grafts with yellow lupin scions. During the waterlogging period, leaf gas exchange decreased by 16–74% in all grafting combinations except in narrow-leafed lupin scion/yellow lupin rootstock where it increased by 17–30%. During waterlogging, stem water potential decreased and leaf osmotic pressure increased. These changes compensated one another and consequently there was no effect on bulk leaf turgor. After 14 days recovery, water relations returned to initial values. Tolerance of the whole plant to waterlogging was influenced more by the root genotype than the shoot genotype. However, production of hypocotyl roots in response to waterlogging was related to the shoot genotype rather than the root genotype.

Narrow-leafed lupin (Lupinus angustifolius) is now an established major crop in southern Australia, albus lupin (L. albus) is grown on a smaller scale, and there is interest in cultivating other lupin species. With any new crop, it is crucial that its phenology, particularly times of flowering and maturity, matches the target environment. We investigated times of flowering, maturity, and seed filling of several lupin species of agricultural interest to southern Australia. Established genotypes of L. angustifolius and L. albus flowered earliest, in 70-75 days, but L. luteus cv. Teo and some L. angustifolius lines with restricted branching matured earliest. Differences between genotypes in rates of seed filling and final seed weights meant that time of maturity was only poorly correlated with flowering time. We investigated the role of photoperiod in the timing of flowering and maturity in 12 lupin species/genotypes by: (a) growing plants under both long days in the UK and short days in Australia; and (b) growing plants under short days in Australia with or without lighting to extend the photoperiod. Flowering was clearly hastened by long days in all genotypes in both situations. However, the responses were much greater when days were naturally longer than when they were artificially lengthened. This was probably due to the illuminance requirements for perception of photoperiod by lupin not being saturated by the artificial lighting.