Development In Bambara Groundnut Research Articles

A multiscale mathematical model describing the growth and development of bambara groundnut

A principal objective in agriculture is to maximise food production; this is particularly relevant with the added demands of an ever increasing population, coupled with the unpredictability that climate change brings. Further improvements in productivity can only be achieved with an increased understanding of plant and crop processes. In this respect, mathematical modelling of plants and crops plays an important role. In this paper we present a two-scale mathematical model of crop yield that accounts for plant growth and canopy interactions. A system of nonlinear ordinary differential equations (ODEs) is formulated to describe the growth of each individual plant, where equations are coupled via a term that describes plant competition via canopy–canopy interactions. A crop of greenhouse plants is then modelled via an agent based modelling approach in which the growth of each plant is described via our system of ODEs. The model is formulated for the African drought tolerant legume bambara groundnut (Vigna subterranea), which is currently being investigated as a food source in light of climate change and food insecurity challenges. Our model allows us to account for plant diversity and also investigate the effect of individual plant traits (e.g. plant canopy size and planting distance) on the yield of the overall crop. Informed with greenhouse data, model results show that plant positioning relative to other plants has a large impact on individual plant yield. Variation in physiological plant traits from genetic diversity and the environmental effects lead to experimentally observed variations in crop yield. These traits include plant height, plant carrying capacity, leaf accumulation rate and canopy spread. Of these traits plant height and ground cover growth rates are found to have the greatest impact on crop yield. We also consider a range of different planting arrangements (uniform grid, staggered grid, circular rings and random allocation) and find that the staggered grid leads to the greatest crop yield (6% more compared to uniform grid). Whilst formulated specifically for bambara groundnut, the generic formulation of our model means that with changes to certain parameter’s, it may be extended to other crop species that form a canopy.

Seed Scarification Improves Physiological Growth and Development of Bambara Groundnut (Vigna subterranea) Depending on Seed Coat Colour

Seed Scarification Improves Physiological Growth and Development of Bambara Groundnut (Vigna subterranea) Depending on Seed Coat Colour

Identification of Gene Modules Associated with Low Temperatures Response in Bambara Groundnut by Network-Based Analysis.

Bambara groundnut (Vigna subterranea (L.) Verdc.) is an African legume and is a promising underutilized crop with good seed nutritional values. Low temperature stress in a number of African countries at night, such as Botswana, can effect the growth and development of bambara groundnut, leading to losses in potential crop yield. Therefore, in this study we developed a computational pipeline to identify and analyze the genes and gene modules associated with low temperature stress responses in bambara groundnut using the cross-species microarray technique (as bambara groundnut has no microarray chip) coupled with network-based analysis. Analyses of the bambara groundnut transcriptome using cross-species gene expression data resulted in the identification of 375 and 659 differentially expressed genes (p<0.01) under the sub-optimal (23°C) and very sub-optimal (18°C) temperatures, respectively, of which 110 genes are commonly shared between the two stress conditions. The construction of a Highest Reciprocal Rank-based gene co-expression network, followed by its partition using a Heuristic Cluster Chiseling Algorithm resulted in 6 and 7 gene modules in sub-optimal and very sub-optimal temperature stresses being identified, respectively. Modules of sub-optimal temperature stress are principally enriched with carbohydrate and lipid metabolic processes, while most of the modules of very sub-optimal temperature stress are significantly enriched with responses to stimuli and various metabolic processes. Several transcription factors (from MYB, NAC, WRKY, WHIRLY & GATA classes) that may regulate the downstream genes involved in response to stimulus in order for the plant to withstand very sub-optimal temperature stress were highlighted. The identified gene modules could be useful in breeding for low-temperature stress tolerant bambara groundnut varieties.

TEMPERATURE AND DROUGHT STRESS EFFECTS ON GROWTH AND DEVELOPMENT OF BAMBARA GROUNDNUT (VIGNA SUBTERRANEA L.)

SUMMARYThe effect of drought and temperature on the growth and development of bambara groundnut (Vigna subterranea (L.) Verdc.) was studied in controlled environment glasshouses in the United Kingdom. There were two landraces, S19-3 (from a hot, dry environment; Namibia) and Uniswa Red (from a cool, wet environment; Swaziland), two temperature regimes (23 °C and 33 °C) and three watering regimes (2006; fully irrigated), 2007 (drought imposed at 77 days after sowing (DAS)) and 2008 (drought imposed at 30 DAS)). Bambara groundnut responded to drought by slowing the rate of leaf area expansion and reducing final canopy size and total dry matter (TDM). Drought also caused significant reductions in pod dry matter, pod numbers and harvest index (HI), leading to a decrease in final yield that was different between landraces. Throughout the three growing seasons, landraces grown at 33 °C produced more TDM than the landraces grown at 23 °C. The two landraces differed in their phenology; S19-3 exhibited a reduced phenology where leaf numbers started to decrease before Uniswa Red at both temperatures, while Uniswa Red maintained the longest life cycle. The lowest pod yield was produced by Uniswa Red in 2008 at 33 °C (maximum of 35.5 gm−2), while S19-3 produced a minimum pod yield of 56.6 gm−2 at 33 °C, also in 2008. However, both landraces produced considerably more pod yield at 23 °C throughout the three growing seasons (minimum of 151 gm−2 and 162 gm−2 for Uniswa Red and S19-3, respectively). Under moderate drought, S19-3 at 33 °C gave the highest pod yield (365 gm−2) among the treatments throughout the three growing seasons and maintained HI better under drought. Despite being from a hot, dry environment, S19-3 also performed well at low temperature, which indicates the adaptation of S19-3 to low temperature that it also experiences in the country of origin.

Growth and development of bambara groundnut ( Vigna subterranea) in response to soil moisture : 2. Resource capture and conversion

A study was conducted in controlled environment glasshouses to investigate the effects of soil moisture on resource capture and conversion of three landraces (DipC, S19-3 and UN from Botswana, Namibia and Swaziland, respectively) of bambara groundnut ( Vigna subterranea (L.) Verdc.). The study was conducted under two soil moisture treatments: an irrigated control and a drought treatment where irrigation was withheld from approximately flowering to final harvest. Drought reduced the mean fractional intercepted radiation ( f) from 0.8 to less than 0.7 across landraces. The mean light extinction coefficient (=0.46) was not affected either by landrace or watering regime, while cumulative intercepted radiation ( S ci) reduced under drought because of the reduction in f. Drought reduced total transpiration ( E c) only in DipC while it had no effect on the other two landraces. Crops under irrigation extracted most of the water from the top 50 cm of the profile while those under drought extracted water down to 90 cm. The conversion coefficient for intercepted radiation ( ɛ s; g MJ −1) was reduced by 32%, from 1.51 to 1.02 g MJ −1. Similarly, drought reduced the dry matter/transpired water ratio ( ε w ; g kg −1) by 20% from 2.05 to 1.65 g kg −1.

Growth and development of bambara groundnut ( Vigna subterranea) in response to soil moisture : 1. Dry matter and yield

The effect of drought on the growth and development of bambara groundnut ( Vigna subterranea (L.) Verdc.) was studied in controlled-environment glasshouses in the UK. There were three landraces (S19-3, DipC and UN from Namibia, Botswana and Swaziland, respectively) and two watering regimes; a control that was irrigated weekly to 90% field capacity and a drought treatment with no irrigation from 49 days after sowing (DAS) until final harvest (147 DAS). Bambara groundnut responded to drought by reducing the rate of leaf area expansion, final canopy size and total dry matter (TDM) during vegetative growth. Drought also caused significant reductions in pod dry matter (PDM), pod number, seed weight and harvest index (HI), leading to a decrease in final pod yield that was different between landraces. Across landraces, drought reduced mean pod yield from 298 g m −2 to 165 g m −2, representing 45% yield loss. Despite the reduction in all landraces, the mean pod yield across the droughted treatments that had received no water for almost 100 days indicated the resilience of the species to drought. The three landraces differed in their phenology; S19-3 exhibited a reduced phenology while UN maintained the longest life cycle. The different responses of the landraces reflect their adaptation to their local climates where mean annual rainfall ranges between 365 mm (Namibia) and 1390 mm (Swaziland). We discuss the significance of these results for future breeding programmes on bambara groundnut.

Quantifying photothermal influences on reproductive development in bambara groundnut ( Vigna subterranea): models and their validation

The effects of photoperiod and temperature on reproductive development in two bambara groundnut ( Vigna subterranea) selections from contrasting origins were quantified by using linear models. The two selections were ‘DodR94’ from Tanzania (6°10′S) and ‘DipC94’ from Botswana (24°40′S). The models were based on a semicontrolled-environment study with four constant photoperiods (10.5, 11.8, 13.2, and 14.5 h per day, covering the range of photoperiods in the tropics) and four constant temperatures (20, 23, 26, and 29°C). Higher temperatures were also included, but plants died at constant temperatures of 33 and 36°C. The rate of progress from sowing to flowering of both selections could be described by a thermal response plane. For ‘DipC94’, the rate of progress from flowering to podding could be described well by a combination of a thermal response plane and a photothermal response plane. In the case of the podding response of ‘DodR94’, the intervals between the experimental photoperiods were too large to allow quantification of the photoperiod effect. Validation of the photothermal models with the results of glasshouse experiments in The Netherlands and field experiments in Tanzania and Botswana gave mixed results. Predicted and observed time to flowering for ‘DipC94’ corresponded well, and predicted and observed time from flowering to podding reasonably well. Flowering predictions for ‘DodR94’ were not accurate, possibly because flowering in this selection is influenced by long photoperiods at high temperatures.

Development, growth and dry matter partitioning in bambara groundnut (Vigna subterranea) as influenced by photoperiod and shading

A semi-controlled environment study was conducted from May to September 1996 in Wageningen, The Netherlands, to investigate the interaction between growth and development in bambara groundnut (Vigna subterranea) and the influence of photoperiod on dry matter partitioning. The experimental design was a split-plot with four photoperiods (10·5, 11·8, 13·2 and 14·5 h/d) and two light treatments: unshaded and shaded (42% light reduction). The selection used was ‘DipC94’ from Botswana. The dates of 50% flowering and 50% podding were determined, and samples of plants were harvested at 22, 36, 50, 64, 78, 92, 106 and 120 days after sowing. Total dry matter production was 41% lower in the shaded treatment than in the unshaded treatment, but the rates of progress from sowing to flowering and flowering to podding decreased by only 3 and 12% respectively. This suggests that growth and development in bambara groundnut are largely independent. Photoperiod influenced dry matter partitioning indirectly, through its influence on the onset of podding. There were, however, no strong direct photoperiod effects on dry matter partitioning, either before or after the onset of podding.

Phenological development in bambara groundnut (Vigna subterranea) transferred from 14 to 11 h photoperiods

SUMMARYAspects of the photoregulation of phenological development in bambara groundnut were studied in a glasshouse experiment in The Netherlands. The influence of a 14 h photoperiod (which retards podding) during a period of variable length prior to an 11 h photoperiod (which induces podding) on flowering, yield and on the position of pods on the plants was determined. The third generation of three plants of genotype ‘Ankpa 4’ from Nigeria was used as the split-plot factor in a split-plot design with three replicates. The main plots were four daylength treatments: a period of 21, 28, 41 or 54 days under the 14 h photoperiod before transference to the 11 h photoperiod. Plants transferred after 28 or more days started flowering sooner the earlier they were transferred. Plants transferred after 21 and 28 days began flowering at the same time (51 days after sowing), thus indicating juvenility. At harvest, 135 days after sowing, the total seed dry weight per plant was higher for plants transferred after 41 and 54 days than for plants transferred after 21 days. Plants transferred after 28 days gave an intermediate value. Most (79–91%) pods were produced on branches that developed on nodes 1–4 of the main axis. There were no differences in the fractional distribution of the pods along the main axis in plants transferred after 28 or more days. Pods of plants transferred after 21 and 28 days were more evenly distributed over the nodes of the first two primary branches than pods of plants transferred after 41 and 54 days. Plants of the latter treatments produced their pods more towards the tips of the branches and concentrated on two neighbouring nodes (nodes 5 and 6 for plants transferred after 41 days and nodes 6 and 7 for plants transferred after 54 days). Delaying the induction of podding in this experiment therefore resulted in higher seed yields per plant and a more synchronized development and hence maturity of pods.

Phenological development in bambara groundnut (Vigna subterranea) at alternate exposure to 12 and 14 h photoperiods

SUMMARYThe developmental phase in which photoperiod sensitivity for podding occurs was determined for two bambara groundnut genotypes grown in 1987 and 1990 in glasshouse experiments in the Netherlands, namely genotypes ‘Tiga Nicuru’ from Mali (day-neutral for flowering and photoperiod-sensitive for podding) and ‘Ankpa 4’ from Nigeria (photoperiod-sensitive for both flowering and podding). Eighteen photoperiod treatments were given to each genotype. Two treatments consisted of a constant 12 or 14 h photoperiod and started 21 days after sowing for ‘Tiga Nicuru’ and 18 days after sowing for ‘Ankpa 4’. Eight treatments were introduced by transferring plants with at least 20 flower buds (33-day-old plants of ‘Tiga Nicuru’ and 35-day-old plants of ‘Ankpa 4’) from a 12 to a 14 h photoperiod or vice versa. In ‘Tiga Nicuru’ transference was for 4, 8, 12 days or until harvest, and in ‘Ankpa 4’ it was for 8, 12, 16 days or until harvest. Another eight similar treatments were given to plants transferred after having had at least 20 open flowers (48-day-old plants of ‘Tiga Nicuru’ and 62-day-old plants of ‘Ankpa 4’). Transferring plants of ‘Tiga Nicuru’ to the 12 h photoperiod for at least 8 days induced podding. Plants were susceptible to podding induction for nearly 4 weeks: podding was induced in plants which had been in the natural photoperiod (≥ 15·5 h) for 21 days, followed by 12 days in the 12 h photoperiod and subsequently in the 14 h photoperiod until harvest, and it could still be induced in 48-day-old plants that had had &gt; 20 open flowers. However, transference to the 12 h photoperiod for 16 days did not induce podding in ‘Ankpa 4’. Transferring plants from the 12 to the 14 h photoperiod or vice versa caused differences in the number of flowers and pods/plant, petiole length and leaf area. The influence of photoperiod was most obvious on the number of pods/plant. Leaf area and number of pods/plant seem suitable parameters for modelling crop growth under different photoperiods. Leaf area development correlated with the number of developing pods/plant, but was also more directly influenced by the prevailing photoperiod.

Phenological Development in Bambara Groundnut (Vigna subterranea) at Constant Exposure to Photoperiods of 10 to 16 h

The flowering and fruit-set of a bambara groundnut selection from Ankpa, Nigeria, were studied in greenhouses at constant exposure to photoperiods of 10, 12, 12·5, 13, 14 and 16 h. The development of embryos was determined in ovaries from plants under photoperiods of 11·5 h and ⩾ 14 h. The beginning of flowering, recorded as the number of days from sowing to the first open flower, was delayed by lengthening the photoperiod. It started 7 d later under 16 h than under 10 h. This difference increased during the production of the next nine open flowers. Lengthening the photoperiod also caused a delay in the beginning of fruit development. Under 13 h it was delayed by more than 40 d compared with fruit development under 10 h. Some plants under 14 and 16 h even failed to produce pods. After the beginning of fruit development dry matter partitioning to pods was substantially less under 14 and 16 h photoperiods than under photoperiods of 13 h or less; this was reflected in a strong reduction of pod growth rates.Under an 11·5 h photoperiod two groups of ovaries could be distinguished. In both, embryo development was identical up to 17 d after anthesis, but then the embryos in the first group continued to develop until they were full-grown at about 41 d after anthesis, whereas the growth of the embryos in the second group stopped. Embryo development under a photoperiod of ⩾ 14 h was similar to that in the ovaries with discontinued embryo growth under the 11·5 photoperiod. Healthy-looking embryos were found in ovaries up to 32 d after anthesis under a photoperiod ⩾ 14 h. From then onwards embryos started to shrivel and degenerate. Finally, the ovaries aborted.

Preliminary observations on photoperiod regulation of phenological development in bambara groundnut (Vigna subterranea)

The effects of photoperiod on the development of bambara groundnut ( Vigna subterranea (L.) Verdc.), a leguminous food crop cultivated mainly in Africa, were studied. In eight selections from the International Institute of Tropical Agriculture, two groups were distinguished: (a) day-neutral for flowering, with fruit-set delayed by long photoperiods (14 h); and (b) day-neutral for flowering, with fruit-set inhibited by long photoperiods. Two more categories, (c) delayed flowering and no fruit-set under long photoperiods, and (d) no flowering at long photoperiods, were found in later research, not reported here, on other selections. The delay or absence of fruit-set in long photoperiods is caused by the growth of fertilized ovaries being checked. Photoperiod affects plant phenology; plants grown in a 14-h photoperiod continue leaf production much longer than plants grown in 10-h or 12-h photoperiods, and therefore after 101–103 days their leaf areas may be three times larger.