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Narrow-leafed lupin (Lupinus angustifolius) is an important dryland crop, providing a protein source in global grain markets. While agronomic practices have successfully controlled many dicot weeds among narrow-leafed lupins, the closely related sandplain lupin (Lupinus cosentinii) has proven difficult to control, reducing yield and harvest quality. Here, we successfully trained a segmentation model to detect sandplain lupins and differentiate them from narrow-leafed lupins under field conditions. The deep learning model was trained using 9171 images collected from a field site in the Western Australian grain belt. Images were collected using an unoccupied aerial vehicle at heights of 4, 10, and 20 m. The dataset was supplemented with images sourced from the WeedAI database, which were collected at 1.5 m. The resultant model had an average precision of 0.86, intersection over union of 0.60, and F1 score of 0.70 for segmenting the narrow-leafed and sandplain lupins across the multiple datasets. Images collected at a closer range and showing plants at an early developmental stage had significantly higher precision and recall scores (p-value < 0.05), indicating image collection methods and plant developmental stages play a substantial role in the model performance. Nonetheless, the model identified 80.3% of the sandplain lupins on average, with a low variation (±6.13%) in performance across the 5 datasets. The results presented in this study contribute to the development of precision weed management systems within morphologically similar crops, particularly for sandplain lupin detection, supporting future narrow-leafed lupin grain yield and quality.

Genetic variability in bacterial populations that nodulate Lupinus cosentinii in Tunisia was investigated. Phylogenetic studies of 40 isolates using recA partial sequences categorized them into three clusters within the Bradyrhizobium genus. Twenty-three strains selected from the three clusters were thoroughly examined through housekeeping genes (recA, glnII and rpoB) multilocus sequence analysis (MLSA). Our results showed that 23 representative strains were distributed in five distinct clusters, with 13 strains belonging to Bradyrhizobium canariense BTA-1T/Bradyrhizobium lupini USDA3051T (10 strains) and Bradyrhizobium hipponense aSej3T (three strains) lineages. Interestingly, eight strains occupied a separate position and could belong to two putative novel Bradyrhizobium species. The nodC phylogeny placed the 23 strains within three symbiovars: genistearum (19 strains), lupini (two strains) and, for the first time, the symbiovar cyanophyllae (two strains). Based on the worldwide phylogeography of rhizobial symbionts nodulating lupine (14 species), our results reported that eight species occurred in more than one continent, and six species were specific for one continent, e.g., Bradyrhizobium rifense, Bradyrhizobium diazoefficiens, Phyllobacterium sp. and Devosia sp. were specific to the African continent, the Bradyrhizobium iriomotense/Bradyrhizobium stylosanthis group to America, and Bradyrhizobium valentinum to the European continent.

Molecular cytogenetic analysis of Lupinus angustifolius and Lupinus cosentinii was performed using flow cytometry, fluorescence in situ hybridisation (FISH) and differential chromosome staining. Genome size was determined as 2.07 pg for L. angustifolius and 1.54 pg for L. cosentinii. Analysis of nuclear DNA amount in cells during plant development has shown endopolyploidisation in different organs. The highest level of endopolyploidy was in cotyledons and reached 32C in L. angustifolius and 64C in L. cosentinii. Both of the investigated Lupinus species belong to the polysomatic type of plants. Double FISH with rDNA probes provided chromosomal landmarks for 10 out of 40 chromosomes for L. angustifolius and 8 out of 32 chromosomes for L. cosentinii. In L. angustifolius, the number and localisation of 25S rDNA hybridisation signals precisely corresponded to the chromomycin A3 (CMA(+)) bands, while in L. cosentinii both 25S and 5S rDNA loci overlapped with CMA(+) bands. Silver staining revealed that only 45S rRNA genes located in secondary constriction regions were transcriptionally active. FISH with Arabidopsis-type telomeric arrays revealed the presence of signals at termini of all chromosomes. Despite the application of different DNA probes for FISH and different chromosome staining, a relatively small proportion of chromosomes in the Lupinus karyotypes can be distinguished. Identification of all chromosomes requires the use of more chromosome-specific markers.

Seed globulins isolated from 58 accessions representing 12 Old World Lupinus species were studied using two techniques of high-performance liquid chromatography (HPLC): reversed-phase (RP-HPLC) and ion-exchange (IE-HPLC). Differences in quantitative and qualitative composition of globulins between smooth-seeded and rough-seeded lupins appear to be significant. Each investigated species/subspecies is distinguished by its specific protein HPLC pattern of globulins. The number of globulin peaks recorded in particular species varied from four to eight. In total, 72 retention times of protein peaks were distinguished in the investigated taxa. Chromatographic data were subjected to statistical analysis using hierarchical UPGMA grouping of the examined taxa. Heterogeneous smooth-seeded lupins proved to be distantly related to rather homogeneous rough-seeded lupins except for the new species L. anatolicus. Within the rough-seeded lupins three subgroups are distinguished: (1) L. atlanticus, L. cosentinii and L. digitatus, (2) L. palaestinus and L. pilosus and (3) L. princei. The obtained data are discussed with reference to taxonomic relationships in the Old World lupins.

To learn the effect of wind on a species native to a windy site, I compared germination, seedling survival, seedling form, and the force required to uproot seedlings in a wind-exposed and a wind-sheltered site. In February 1992, the sand dune perennial Lupinus arboreus Sims, was planted in wind-exposed and wind-sheltered plots at Bodega Head, California. Half the individuals were planted from seed and the other half were transplanted from nearby. By late July 1992, 26/43 of the germinants or transplants were still alive in the wind-protected plot but only 3/42 in the windexposed plot. This suggests the importance of wind-sheltered sites as safe sites for establishment of this dune species. By 57 days after planting the average plant was smaller in the wind-exposed than the wind-swept plot (P < 0.05), but those seedlings that would survive until harvest (day 151) were significantly larger in both plots than those that would die (P < 0.05). These data suggest that rapid early growth was important to survival. The wind-exposed survivors at day 151 (n = 4) tended to have morphologies more resistant to wind: they averaged twice the stem diameter (2 cm above the ground) and half the height of wind-protected plants (n = 28). There were no significant differences in the force required to uproot plants by treatment (P < 0.05). Two non-native lupines were also planted from seed to learn how congeners respond to wind. Germination, establishment, and growth of L. cosentinii Guss. plants were unaffected by wind, perhaps because the large seed permits rapid development of a taproot to aid in water acquisition. Seedlings of L. angustifolius L. cv. Ganja died quickly after total defoliation by caterpillars, suggestive of a major role of chemical defenses for survival of lupines at this sand dune site.

The influence of pasture species and pasture/crop rotations on the fate of K fertilizer in the soil profile of a sandplain soil was investigated. Results for Lupinus cosentinii, subterranean clover and a subterranean clover/wheat rotation are presented. Potassium was applied as KCl at six rates up to 150 kg K ha⁻¹ for three years; bicarbonate-extractable K was measured at five depths in the profile (0-100 cm) for four years. The net change in available K in the top 100 cm of the profile (kg ha⁻¹) was calculated. There was a gradual increase in K down the profile under all species with fertilizer application. The increase was largest for L. cosentina, which also appeared to redistribute K from below 100 cm to the soil surface. The K residual value on this soil type was higher than expected with most of the fertilizer applied over three years being retained in the top 100 cm.