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Aim: This study aims to evaluate the impact of seed primimg with soil microorganism on the germination and metabolism of pearl millet seeds when exposed to the allelopathic effects of some specific weed extracts. Methods: Pearl millet seeds were categorized into five distinct groups. Four of these groups were subjected to priming with different soil microorganisms: Bacillus velezensis, Pseudomonas fluorescens, Serratia marcescens, and Trichoderma viride. The remaining, fifth group underwent hydropriming. Subsequently, these groups were subjected to germination in the presence of weed extracts, a process that extended over five days. Following germination, various factors were assessed, including germination percentage, radicle and plumule length, and seed vigor. Furthermore, the study encompassed the analysis of biochemical parameters such carbohydrate and phytate hydrolysis, oxidative stress markers, antioxidant enzyme activity, and secondary metabolite. Results: The findings of the study revealed that biopriming of pearl millet seeds with soil microorganisms led to a significant enhancement in germination, even when exposed to different weed extract treatments. This improvement was chiefly manifested through heightened levels of antioxidant enzymes, which mitigate the oxidative stress induced by the weed treatments. Moreover, the biopriming process improved the hydrolysis in germinated seeds, resulting in energy savings and a reduction in carbon utilization for secondary metabolism through the shikimic acid pathway and the phenylpropanol pathway. This facilitated the production of defense molecules like phenols and flavonoids. Conclusion: Seed priming with soil microorganism ultimately bolsters the seeds' tolerance against allelochemicals originating from weed residue treatments. [ABSTRACT FROM AUTHOR]

Background and aims: Cover crops are an integral constituent of sustainable subtropical agroecosystems. Using grass/legume mixtures as opposed to monocultures has the potential to maximize their multifunctionality. This project aimed to understand temporal patterns of nitrogen (N) release of cover crop monocultures and mixtures in a subtropical vegetable production system. Methods: A litterbag experiment was established to study N release patterns of two commonly used grasses, two legumes, four two-species mixture each with one grass and one legume, and one four-species mixture. This field experiment was complemented by two laboratory incubations to quantify soil N mineralization after the termination of cover crops in 2020 and 2021. Results: The majority of residue N (> 60%) was lost in the first month of decomposition, suggesting no or minimal N release from cover crops beyond one cropping season. Mixtures enhanced N release relative to monocultures within the first two months; however, the timing of this synergistic effect depended on grass species in the mixture. Initial residue N concentration reasonably predicted the N loss trajectory of all residue types (r = -0.72; p < 0.05). Legumes showed the highest N mineralization rate, followed by mixtures and lastly grasses. Conclusions: Our findings reveal significant temporal variability in N release among different cover crop mixtures, despite the rapid decomposition across all cover crop treatments. Selection of appropriate species in cover crop mixtures helps to facilitate the synchronization of N release and crop update in subtropical systems where N management is extremely time sensitive. [ABSTRACT FROM AUTHOR]

Background and aims: Calcium deficiency is evident in populations worldwide and combating this could be addressed with the biofortification of staple crops. Consequently, identification of Ca concentration in breeding trials would be essential. Here we report the use of energy dispersive x-ray fluorescence (EDXRF) for the rapid screening of Ca concentration in seed samples. Methods: Grain samples of rice, wheat, pearl millet, bean, maize, and cowpea were provided from biofortification breeding programs and analysed with inductively coupled plasma – mass spectrometry (ICP-MS) to determine the reference Ca concentration. A set of samples were used to develop a Ca EDXRF calibration for each crop and another set of samples to validate the method. Results: The EDXRF results were comparable to the reference ICP-MS analysis with an average difference of < ± 5 mg kg-1 for all crops and RSD for duplicate analysis < 10% for all crops. Conclusions: EDXRF is suitable for the rapid analysis of Ca in bean, cowpea, wheat, pearl millet, maize and rice samples. [ABSTRACT FROM AUTHOR]

Aims: The interactions between plant roots and the associated microbiota impact soil aggregation, water retention and plant nutrient availability. Thus, selection of plant genotypes that promote microbial species involved in root-adhering soil aggregation and rhizosheath formation could help improve yield sustainably. Here, we tested pearl millet genotypic variation in both root-adhering soil aggregation, microbiological and biochemical characteristics. Methods: A collection of 181 pearl millet inbred lines was phenotyped for their rhizosheath size, and 13 contrasting genotypes were selected and grown under field conditions, and their root-adhering soil (RAS) was sampled. Microbial biomass, pH, mineral N content and six enzymatic activities involved in main nutrients cycles were analyzed, and metabarcoding of 16S rDNA and ITS were performed for bacterial and fungal diversity. Results: Enzymatic activities (chitinase, acid phosphomonoesterase, FDA-hydrolysis and β-glucosidase) were higher in RAS of larger rhizosheath lines than that of smaller rhizosheath one. Bacterial β-diversity showed a separation of the most contrasting lines in the principal coordinate analysis performed with the Bray-Curtis distance matrix. Some bacteria from the Gaiellaceae and Sphingomonadaceae families and the Bradyrhizobium and Mesorhizobium genera were associated with the large rhizosheath phenotype. Concerning the fungal community, we noticed a negative correlation between the specific richness and the rhizosheath size and Trichoderma genus was positively associated to the rhizosheath size. Conclusions: This study demonstrates that in pearl millet, the rhizosheath size is related to soil nutrient dynamics and microbiota diversity. However, it also shows that other factors shape this trait and their relative importance must be determined. [ABSTRACT FROM AUTHOR]

Aims: Cover crop species selection for soybean (Glycine max) production under no-tillage (NT) management may affect soil organic C sequestration by altering the quantity and quality of C inputs, thereby affecting cropping system sustainability. If so, the underlying mechanisms for such regulation are still unclear. Methods: We assessed changes in soil C and N fractions at 0-0.1 m depth and soil C stock at 0-0.6 m depth during the last three years of dry-season cover cropping in a soybean production system managed with NT for 9 years on a Rhodic Hapludox in Sao Paulo, Brazil. Dry-season management treatments were repeated yearly in a split-plot scheme. Main plots during the fall-winter were (1) ruzigrass (Urochloa ruziziensis), (2) grain sorghum (Sorghum bicolor), and (3) the intercropping of ruzigrass and sorghum. Subplots during spring prior to planting soybean were (a) pearl millet (Pennisetum glaucum), (b) sunn hemp (Crotalaria juncea), and (c) forage sorghum (Sorghum bicolor). Results: Soil C and N fractions were affected according to crop residue characteristics of the rotations. Higher soil C stocks in 2012 and 2015 (7 % an average) were observed at 0.2–0.4 m depth by ruzigrass compared to sorghum. High crop residue input with ruzigrass in the fall-winter sequestered 0.61 Mg C ha− 1 yr− 1 at 0-0.1 m soil depth compared with lower C sequestration using grain sorghum (0.29 Mg C ha− 1 yr− 1). Conclusions: The quantity and quality of crop residues impact its retention on soil surface controlling the dynamics of soil C and N fractions and can be considered relevant for soil C sequestration. These aspects could contribute to the mitigation of atmospheric CO2 in crop production systems. [ABSTRACT FROM AUTHOR]

Aims: As soil dries, the loss of soil hydraulic conductivity limits water supply to the leaves, which is expected to generate a nonlinear relationship between leaf water potential (ψleaf) and transpiration (E). The effect of soil drying and root properties on ψleaf and E remains elusive. Methods: We measured E and ψleaf of pearl millet for varying E and soil moisture using a root pressure chamber. A model of water flow in soil and plant was used to fit the ψleaf (E) relationship. Results: The relation between ψleaf and E was linear at all soil moistures. The slope of ψleaf (E) increased with decreasing soil moisture due to the decreasing soil-root conductance. The fact that the relation remained linear also in dry soils and high E is surprising. Indeed, it indicates that the gradients in soil water potential (ψsoil) were small, probably because of the large root surface (13.5 cm cm−3) active in water uptake. ψleaf at E = 0 was less negative than ψsoil, indicating a more negative osmotic potential in the xylem than in the soil. Conclusions: We propose that the linearity between ψleaf and E and the high ψleaf (E = 0) compared to ψsoil support transpiration in drying soils. [ABSTRACT FROM AUTHOR]

Aims: To investigate the physiological responses of groundnut (Arachis hypogea) and pearl millet (Penisetum glaucum) that were intercropped with the native evergreen woody shrubs Piliostigma reticulatum (D.C.) Hochst and Guiera senegalensis J.F. Gmel compared to control crops throughout two growing seasons at two sites with contrasting climate and soil types in Senegal.Methods: Shrubs grown in groundnut and millet fields at higher than native density were coppiced annually with aboveground biomass returned to the soil and no additional fertilizer. Crop leaf area index (LAI), handheld normalized difference vegetation index (NDVI), leaf water potential, and soil moisture and temperature were monitored in 2012-2013.Results: At the drier site, the presence of shrubs reduced soil temperature at 5 cm depth by up to 5 °C during early crop growth. Shrub presence increased LAI by up to 266%, NDVI by up to 217% and increased groundnut leaf water potential throughout the day at the wetter site. Shrub effects on crop physiology were stronger overall at the drier site.Conclusions: These results improve the understanding of how this unique agroforestry system alters the growing environment and the physiological response of associated crops throughout the season. [ABSTRACT FROM AUTHOR]

Aims: Rice is often cultivated in drought-prone regions causing growth inhibition. Therefore, we investigated whether close mixed planting of rice with pearl millet would mitigate these effects.Methods: We used pot and lysimeter to evaluate whether close mixed planting with pearl millet is more effective than single-stand planting in suppressing the growth inhibition of rice (NERICA4) under drought.Results: Close mixed planting only slightly alleviated the growth inhibition of rice under drought in the pot experiment and the first year lysimeter experiment, but mitigated this in the second year lysimeter experiment due to the lower levels of competition. Deuterated water applied from the bottom of the pot and lysimeter was present at a higher concentration in the xylem sap of rice under close mixed planting than under single-stand planting, and this tendency was enhanced by drought. Partitioning of the available water between the two crops was also observed under close mixed planting, with the rice and pearl millet depending on water from the soil surface and deep soil, respectively.Conclusions: Close mixed planting with pearl millet effectively mitigates the growth inhibition of rice under drought due to the increased access to deep water and the partitioning of available water between the two crops. [ABSTRACT FROM AUTHOR]

Background: Nitrate leaching is a primary pathway of nitrogen loss from agricultural systems, and is affected by both tillage and cropped species. However, there is little information on conservation systems without nitrogen fertilization.Methods: Nitrate leaching was assessed in soybean (Glycine max) cropped in rotation with the following cover crops under no-till and chiseling: ruzigrass (Brachiaria ruziziensis), grain sorghum (Sorghum bicolor), pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor), Sunn hemp (Crotalaria juncea), triticale (X Triticosecale) and sunflower (Helianthus annuus).Results: Ruzigrass and grain sorghum cropped in the fall/winter resulted in similar NO3− leaching, which was greater under sunflower than under triticale, likely due to high N uptake and immobilization in plant residues. Sunn hemp as a spring crop resulted in higher NO3− leaching than pearl millet at two locations and forage sorghum at one location likely due to a higher N input by biological fixation. Millet resulted in the lowest N leaching by depleting the soil solution. Chiseling/fallow resulted in higher nitrogen leaching as compared with non-fixing N cover crops.Conclusions: Even when N is not applied, it is important to intensify cropping systems in tropical environments using cover crops with vigorous root systems and high N demand, which prevent N leaching, as well as provides N to the following crop as the straw is mineralized. [ABSTRACT FROM AUTHOR]

Aims: Pearl millet [ Pennisetum glaucum (L.) R. Br.] open-pollinated varieties, which are the predominant cultivars, have never been systematically evaluated for adaptation to low-soil phosphorus (P), a major constraint on pearl millet production in West Africa (WA). Methods: We evaluated grain yield (GY), flowering time (FLO), harvest index (HI), and residual grain yields (RGY) of 102 open-pollinated varieties from WA under low-P (−P) and high-P (+P) field conditions in six environments of WA. In addition, PE-related traits of the varieties were evaluated at early growth stage in a pot experiment. Results: Significant genetic variation was observed for GY, FLO, HI and PE-related traits. P-efficient varieties had higher yield under −P conditions. Varietal performance under −P varied across environments depending on FLO, relative flowering delay under −P (FD) and RGY measured in the field. Low-P-susceptible varieties had higher FLO, lower HI than low-P-tolerant varieties. Response to direct selection under −P field conditions was 20.1 g m, whereas indirect selection response under +P was 16.3 g m. Conclusions: Selection under −P field conditions while taking into account seasonal variations for FLO, FD and PE is expected to be important for improving GY specifically targeting −P environments in WA. [ABSTRACT FROM AUTHOR]

Background and aim: Intuitively, access to water from the soil at key phenological stages is important for adaptation to drought. This study aimed to assess the temporal pattern of water extraction under terminal drought stress. Methods: Pearl millet genotypes with varying levels of terminal drought tolerance were grown in a lysimetric system with a soil volume and plant spacing similar to field conditions. Water extraction was monitored until maturity under differing water regimes. Results: The yield did not differ among genotypes under well-watered (WW) conditions, and the water extraction profile of WW plants was similar across all genotypes. In contrast, the yield of sensitive genotypes was 30-100 % lower than that of tolerant lines under water stress (WS). The total volumes of water extracted by tolerant and sensitive genotypes were similar under WS; however, tolerant genotypes extracted less water prior to anthesis, and more water after anthesis. Grain yield was positively related to the amount of water extracted during week three after panicle emergence. Increased water extraction after anthesis benefitted the tillers more than the main culm and was correlated with higher staygreen scores. Conclusion: Increased water uptake after anthesis, which results from earlier water conservation during pre-anthesis, increases yield under terminal drought in pearl millet. [ABSTRACT FROM AUTHOR]

Background and aims: Rice ( Oryza sativa L.) and pearl millet ( Pennisetum glaucum L.) biofortification breeding programs require accurate and convenient methods to identify nutrient dense genotypes. The aim of this study was to investigate energy-dispersive X-ray fluorescence spectrometry (EDXRF) for the measurement of zinc (Zn) and iron (Fe) concentration in whole grain rice and pearl millet. Methods: Grain samples were obtained from existing biofortification breeding programs. Reference Zn and Fe concentrations obtained by inductively-coupled plasma-optical emission spectroscopy (ICP-OES) were used to calibrate the EDXRF instrument. Calibration was performed with 24 samples and separate calibrations were developed for rice and pearl millet. To validate calibrations, EDXRF analyses were conducted on an additional 40 samples of each species. Results: EDXRF results were highly correlated with ICP-OES values for both Zn and Fe in both species (r = 0.79 to 0.98). EDXRF predicted Zn and Fe in rice to within 1.9 and 1.6 mg kg of ICP-OES values, and Zn and Fe in pearl millet to within 7.6 and 12.5 mg kg of ICP-OES values, at a 95% confidence level. Conclusion: EDXRF offers a convenient, economical tool for screening Zn and Fe concentration in rice and pearl millet biofortification breeding programs. [ABSTRACT FROM AUTHOR]

Root-associated bacteria can have beneficial effects on their host plants. Microbial products can promote and stimulate plant growth or lead to bioprotection against pathogens. This study aimed to isolate putatively beneficial bacteria from traditional cereals grown by subsistence farmers in the Kavango of Namibia. Bacteria were isolated from surface-sterilized roots of Pennisetum glaucum, Sorghum bicolor, and Zea mays, and subjected to phenotypic and phylogenetic analyses. A total of 44 root-associated bacterial strains were isolated. From 33 distinct isolates, 22 belonged to Firmicutes and Actinobacteria, while 11 were Proteobacteria. Eleven novel phylotypes were among the isolates. Features known to contribute to plant growth-promotion and biocontrol were tested in vitro and revealed promising candidates with multiple beneficial characteristics. This is the first report on the characterization of native isolates associated with important agriculture crops in the Kavango region of Namibia. Such isolates have the potential for application as inoculants adapted to poor soils and local crops. Desiccation-tolerant or sporulating Gram-positive bacteria are of particular interest for this region, which is characterized by a long dry season. [ABSTRACT FROM AUTHOR]

In direct sowing, desiccation of the cover crops with herbicides can affect N availability in agroecosystems, reducing N use efficiency by the crop in succession. In this sense, the objective of the study was to evaluate nitrogen losses in the soil–plant system after application of the herbicides glyphosate and glufosinate-ammonium on pearl millet [ Pennisetum glaucum (L.) R. Brown, var. ADR500]. Plants were grown in a sandy soil, fertilized with 15N ammonium sulfate, at N dose of 135.7 mg kg−1. After herbicide application, the N distribution within the plant was changed, with an observed N reduction in leaves and increased N in stalks. The glyphosate and glufosinate reduced, by 25 and 30%, respectively, the amount of N in plant tissues and increased by 3.0 g m−2 the losses in the soil–plant system of the N provided from the fertilizer. This information can be useful in preparing management strategies that will provide greater nitrogen fertilization effectiveness and, consequently, smaller environmental impacts from the use of nitrogen fertilizers and herbicides. [ABSTRACT FROM AUTHOR]

Many microbial turnover processes in acidic sandy subtropical soils are still poorly understood. In a 59-day pot and a 189-day laboratory incubation experiment with two West African continuous cereal soils, the effects of 2 mg g−1 root residues were investigated on growth of sorghum seedlings, soil microbial biomass and activity indices, using cowpea, groundnut, pearl millet, maize and sorghum. The effects of root residues were compared with mineral P or mineral P + N treatments and with a non-fertilized control treatment. On the Alfisol (Fada, Burkina Faso), shoot dry mass was always significantly higher than on the Ultisol (Koukombo, Togo). Highest shoot dry mass was observed after application of mineral P + N on the Alfisol and after mineral P alone on the Ultisol. The application of legume root residues led to small and non-significant increases in dry mass production compared to the non-amended control, whereas the application of cereal root residues led to a decline, regardless of their origin (millet, maize or sorghum). Contents of microbial biomass C, microbial biomass N and ergosterol were 75 to 100% higher in the Alfisol than in the Ultisol, while ATP was only 36% higher. Organic amendments increased ergosterol concentrations by up to 145% compared to the control and mineral P application. Microbial biomass C and microbial biomass N increased by up to 50% after application of root residues, but ATP only up to 20%. After application of legume root residues, cumulative CO2 production was similar in both soils with an average of 370 µg CO2-C g−1 over 189 days. After application of cereal root residues, cumulative CO2 production was higher in the Alfisol (530 µg g−1) than in the Ultisol (445 µg g) over 189 days. [ABSTRACT FROM AUTHOR]

Despite the evidence for a critical role of Mn in malate decarboxylation and CO2 release for carbon fixation reactions in C-4 plants, there is a lack of information on their Mn requirement. The objective of this study was to establish Mn levels needed for optimum growth and photosynthesis of four agriculturally important C-4 species, NAD-ME C-4 pearl millet and purple amaranth, and NADP-ME C-4 corn and sorghum, as compared to two C-3 species, wheat and squash. Plants were grown hydroponically in a complete nutrient solution with Mn concentrations ranging from 0 to 100 μM. We report that under these conditions, C-3 and NADP-ME C-4 plants reached their maximum biomass production with 2–5 μM Mn, the concentration commonly used in plant nutrient media. In contrast, Mn concentrations supporting maximum performance of NAD-ME C-4 plants were up to 20-fold higher and ranged between 50 and 100 μM. Although leaf tissue Mn concentrations increased in parallel with Mn nutrition in all plants, the higher leaf Mn had no effect on NADP-ME C-4 or C-3 plants, but it caused a large, up to 100%, increase in net photosynthetic rate in NAD-ME C-4 species. The highest photosynthetic rates across the spectrum of photon flux density were recorded for C-3 and NADP-ME C-4 plants receiving 2–5 μM Mn, and for NAD-ME C-4 species millet and amaranth supplied with 50 or 100 μM Mn, respectively. Squash (C-3) plants were the most sensitive to Mn and their photosynthetic rate was severely depressed with more than 10 μM Mn. The increase in photosynthetic rates of NAD-ME C-4 species occurred without an increase in stomatal conductance, eliminating CO2 uptake as the main cause. We propose that the higher photosynthetic rates in NAD-ME C-4 species supplied with higher Mn were a result of increased activation of the Mn-dependent NAD-ME in bundle sheath cells, producing greater CO2 supply for Calvin cycle reactions. This is, to our knowledge, the first report on a significantly higher Mn requirement for optimum photosynthesis and biomass production of NAD-ME C-4 species. [ABSTRACT FROM AUTHOR]

Increasing population density and food needs in the Sahel are major drivers behind the conversion of land under natural vegetation to arable land. Intensification of agriculture is a necessity for farmers to produce enough food. As manure is scarce and fertilizers expensive, this study looks into the potential role of cowpea ( Vigna unguiculata L.) and short duration fallow in maintaining soil fertility and productivity and in reducing the major weed problem Striga hermonthica (Del.) Benth. The research was carried out ‘on-farm’ in a traditional millet ( Pennisetum glaucum (L.) R.Br.) growing area in the Malian Sahel, near Bankass. The four year experiment combined 0, 2, 5, and 7 years of preceding fallow with (i) 4 years of millet, (ii) 1 year of cowpea + 3 years of millet, and (iii) 1 year of cowpea + 3 years of millet/cowpea inter-cropping. Total millet production (4 years) was 1440 kg ha−1 for all systems with 2, 5 or 7 years of preceding fallow against 1180 kg ha−1 for systems without fallow. Cowpea grain production showed no significant differences between fallow treatments. Over 4 years, all cropping systems produced similar total amounts of millet grain, implying that the millet ‘lost’ during the year with a pure cowpea crop in treatments (ii) and (iii) was compensated within three years, while the cowpea grain production was an additional benefit. Such compensation was however not observed for increasing number of preceding fallow years, showing that there is no additional production benefit in 5–7 years of fallow as compared to 2 years. The soil organic carbon content decreased more slowly in treatments with a cowpea pure crop in 1998 than in the millet pure crop, while overall higher contents were observed after preceding fallow also after four years of cropping. Striga hermonthica infestation decreased linearly with duration of preceding fallow, but also after seven years of fallow and one year of cowpea the hemi-parasitic weed still re-appeared. Overall the intensification through a cowpea pure crop and cowpea intercrop in these millet-based systems improved production and a number of other characteristics of the system, making it more viable. [ABSTRACT FROM AUTHOR]

Winter cover crops can affect N nutrition of the following maize crop. Although legumes have been recommend for maize rotations, in tropical areas grasses may be more interesting because they provide a longer protection of soil surface. Legumes can add N to the system and grasses can compete with maize for the available nutrient. An experiment was conducted in Botucatu, São Paulo State, Brazil, to study N dynamics in the soil surface straw-maize system as affected by N fertilization management and species included in the no-till rotation. Treatments were fallow, black oat (Avena strigosa), pearl millet (Pennisetum glaucum), white lupins (Lupinus albus), black oat fertilized with N. and pearl millet fertilized with N. Maize was grown afterwards in the same plots, receiving 0.0, 60.0 and 120.0 kg ha-1 of N sidedressed 30 days after plant emergence. Soil, straw and maize samples were taken periodically. The highest corn yields were observed when it was cropped after pearl millet fertilized with N. Nitrogen side dressed application up to 120 kg ha-1 was not able to avoid corn yield decrease caused by black oat. Grasses can be recommended in maize rotations in tropical areas, provided they receive nitrogen fertilizer and show no allelopathy. Due to its higher C/N ratio and dry matter yield they are better than legumes, protecting the soil surface for a longer period. Pearl millet is particularly interesting because it enhances N use efficiency by the following maize crop. For a better N availability/demand synchronism, the cover crops should be desiccated right before maize planting [ABSTRACT FROM AUTHOR]

Root sampling in crop stands of low planting density requires reliable information on horizontal distribution of roots. This applies particularly to pearl millet in the Sahel, which is sown at a rate of less than two pockets of seed per m2. The objective of this study was to investigate the spatial variability of root length density (RLD) among sampling positions in an improved management system with ridging and under traditional sowing. RLD between ridges (bR) was lower compared to sampling positions within ridges (wR) at soil depth layers from 0 to 80 cm soil depth. We found a highly significant, positive correlation between the sum of the root length (RL) of four sampling dates (tillering, booting, flowering, and maturity) with shoot dry mass (SDM) at maturity. The square of the correlation coefficient was highest when calculation of RL was based on RLD at all four sampling positions. While SDM exhibited significant differences among three pearl millet varieties, sole root sampling wR at a lateral distance of 60 cm relative to the pocket would not allow for the detection of varietal differences in RL, while all other sampling positions did. The correlation between RL and SDM was considerably improved if information of RLD bR was included. Under traditional sowing, RLD directly under the plant was lower compared to sampling positions at lateral distance 25 and 50 cm from the centre of the pocket, but this effect of sampling position was not significant. RLD estimates within deeper soil layers were not systematically affected by direction and lateral distance. To obtain accurate information about depth of rooting and RL under traditional sowing, samples should be taken from lateral distances between 20 and 40 cm from the pocket centre. [ABSTRACT FROM AUTHOR]

Root parameters are important traits for the acquisition of nutrients and water under resource-limited conditions. In order to investigate the extent of varietal differences in rooting parameters in pearl millet, we compared a total of eight pearl millet varieties in two experiments (ridging and traditional sowing) over four years at the ICRISAT Sahelian Centre, Niger. We found substantial genotypic variation for root length density (RLD), root dry matter, and total root length (RL), but not for specific root length, depth of rooting, or partitioning of roots between topsoil and subsoil (> 20 cm depth). RL showed a highly dynamic pattern over the growing season. RL and shoot dry matter were positively correlated over P supplies and contrasting levels of field productivity. The relationship between RL and grain yield as well as harvest index were less clear. The root fraction responded to variation in soil productivity, increasing from roughly 20% under high productivity to more than 40% at low productivity, but we found no evidence of varietal differences in this trait despite pronounced differences in maturity and plant stature. Identification of pearl millet varieties suited for growth under low input conditions in south-west Niger can potentially make use of existing genotypic variability in root parameters, but we suggest that, due to high variability for root traits, indirect selection for shoot parameters (e.g., number of stems) is more promising than direct selection for RLD or RL. [ABSTRACT FROM AUTHOR]

Assesses the effects of tillage, crop residue incorporation and legume rotation on the growth and yield of sorghum and pearl millet on a loamy sand and a loam soil. Chemical characteristics of a loamy sand; Grain yield of cereal on the loamy sand; Stover yield of sorghum on the loam.

In the original version of this article, equations 4 and 9 unfortunately contained errors [ABSTRACT FROM AUTHOR]

It is well known that surface mulched crop residues (CR) lead to large yield increases of pearl millet (Pennisetum glaucum L.) on acid sandy soils of the West African Sahel. This effect is generally attributed to mulch-induced changes in chemical properties of the surface soil and the protection of millet seedlings from erosive sand storms. However, previous research has failed to separate the anti-erosive effects of CR on plant growth from chemical effects due to the release of nutrients during CR decomposition. To this end a mulching trial with surface applied millet stalks at a rate of 2000 kg ha?1,an equivalent 10% surface coverage obtained by inert polyethylene (PE) tubes and a bare control treatment was conducted from 1992 to 1994on an acid sandy soil in southwest Niger. Across treatments, sand flux at 0.1 m height was more than twice as high in the rainy seasons than in the dry months and mulching reduced sand flux by between 25 and 50% during rainy season storms compared with 67% during the dry season. Over the 21 months measurement period, cumulative erosion by wind and water was almost 270 t ha-1 of soil in unmulched control plots. In mulched plots, in contrast, between 160 and 200 t ha-1 of soil was deposited. Surface soil temperature at 0.01 mdepth reached above 40 deg. C in bare plots but was up to 4 deg. C lower with CR. Mulch reduced soil penetration resistance at 0-0.02 m and 0-0.05 depth by more than half and decreased runoff leading to higher water contents at flowering and grain filling in the upper 0.3 msoil layers in 1993 and throughout the entire profile in 1994, a year with particularly high rainfall. Both mulch types were similarly effective in increasing final stand density of millet in the first two years between 5 and 23% compared with bare control plots. Relative tothe bare control CR mulch effects on total dry matter of millet at harvest increased from 35% in 1992 and 108% in 1993 to 283% in 1994, wherea [ABSTRACT FROM AUTHOR]

Variability in plant growth is high on most sandy soils of the West African Sahel, often requiring extensive destructive sampling for thereliable estimation of treatment effects. A non-destructive method using aerial photographs and topographic measurements integrated in a Geographic Information System (GIS) was evaluated to determine the effects of organic and inorganic soil amendments on the growth of millet [Pennisetum glaucum (L.) R. Br.] and Guiera senegalensis J.F. Grmel. Based on aerial photographs, quantitative methods were developed toestimate the dry matter of millet plants and Guiera coppices presentin the field each year prior to millet sowing. Integrating digital images of both plant species, measurements of the field's topography and a map of the experimental layout in a GIS allowed successful monitoring of the growth of both species as influenced by phosphorus application and the shrub-crop interaction. Regressions between the dry matter of Guiera coppices and the canopy area were good (r = 0.76 to 0.93) and permitted the calculation of the individual coppice dry matter for the entire field with fewer than 40 destructive measurements. The information on coppices' positions extracted from the aerial photographs and the topographic grid used as covariates explained a significant proportion of the millet growth variability. The use of these covariates also improved the precision of the analysis of variance of millet dry matter data by reducing the residual sum of squares by as much as 33% in the first experimental year. The study demonstrates the potential of non-destructive measurements integrated in a GIS to improve the collection and interpretation of data from field experiments. [ABSTRACT FROM AUTHOR]

In the Sahel, short periods of intra-seasonal drought, caused by unfavourable rainfall distribution, often have stronger effect on crop growth than fluctuations in annual rainfall. The interactive effects of nutrient deficiency and water shortage (during panicle initiation, flowering and grain filling) on yield and yield components of pearl millet (Pennisetum glaucum (L.) R. Br.), were studied on-farm along a cultivated slope, during three years with close to average annual rainfall. Grain yield was correlated to plant nutrient availability but not to annual rainfall, which was explained by the capacity of the crop to compensate for damage caused by water shortage during early growth phases. The performance of each yield component was positively correlated to cumulative rainfall during the growth phase when it was formed. Leaf area index (LAI) was very low, and leaf development followed rainfall distribution. Water and nutrients interacted during eachgrowth phase for all fertility levels. Fertilised millet suffered less during water shortage at panicle initiation and at grain filling compared to non-fertilised millet. However, compared to favourable soil water conditions yield components were systematically lower for alltreatments, indicating the synergistic effect of water and nutrients. The results suggest that water availability plays an exclusive roleduring flowering. Grain number dropped significantly due to water shortage and was similar for all treatments. Despite extremely high spatial variability in yields (varying with a factor 46 within the field), a significant slope effect was observed, of progressively increasing yields when moving downslope. Spatial redistribution of surface runoff resulting in higher soil water availability on lower slope positions, contributed to the yield gradient, which was reinforced for fertilised millet. For each drought period, yield components suffered systematically more upslope than downslope. This slope effect was smoothed [ABSTRACT FROM AUTHOR]