Elementary Plot Research Articles

Evaluation of the resistance of three maize varieties to Spodoptera frugiperda (J.E. Smith) and Ostrinia nubilalis Hübner in the Tonkpi region (Man, Côte d’Ivoire)

BackgroundThe corn borer Ostrinia nubilalis and the fall armyworm Spodoptera frugiperda larvae feed on the aerial parts of maize. It is responsible for significant yield losses and are therefore a cause of food insecurity. This study carried out to evaluate the resistance of three maize varieties (EV8766 SR-MRP, PR9131-SR, CEW-SR), in Tonkpi region’s, to S. frugiperda and O. nubilalis damages. Each maize variety seeds were sown on a one hectare plot subdivided into 6 elementary plots with 75 cm between rows and 40 cm between bunches. Sampling of S. frugiperda and O. nubilalis larvae on maize plants was carried out according to the FAO method, from the third to the fifth week after planting. Maize plants damaged, the intensity of infestation and the number of larvae on maize plants were recorded. Maize plants damaged by the insect pests were marked to avoid recounting. At maturity, 100 maize cobs were harvested per elementary plot, then the larvae number and the attacked cobs by S. frugiperda and O. nubilalis larvae were recorded.ResultsThe lowest damage rate by S. frugiperda were recorded in maize variety EV8766-SR-MRP (23.33%); while, the highest damage rate were in the varieties PR9131-SR (43.33%) and CEW-SR (55%). There are no significant difference values of the density of S. frugiperda larvae per maize plant attacked between the three varieties. The index of intensification of maize plant damaged by S. frugiperda larvae was lower for the variety EV8766-SR-MRP (7.50%) and was moderate for the varieties PR9131-SR (15.42%) and CEW-SR (21.67%). The damage rates of O. nubilalis larvae on maize cobs varied between 9.6 and 22.0%. These damage rates were higher for the varieties PR9131-SR (21.83%) and CEW-SR (17.50%) and were lower for EV8766-SR-MRP (9.66%). There was not significantly different from the density of O. nubilalis larvae per maize cob attacked between the three varieties. It was between 1 to 1.2 larvae. Crop losses were lower for EV8766 SR-MRP (10.228%) than those of PR9131-SR and CEW-SR (19.338%).ConclusionsThe maize variety EV8766-SR-MRP is found to be the best variety in the control of, O. nubilalis and S. frugiperda.

Integration of Fish and Poultry Farming into Cropping Systems to Improve Production Yields

This study aims to evaluate and compare the fertilizing effects of fish-breeding water and river water combined or not with composted poultry manure on the growth and production of okra and lettuce crops. Thus, a sample of 2000 Nile tilapia Oreochromis niloticus fry and a sample of 100 Cobb 500 strain chicks were reared and monitored for six months and fifteen days. Poultry manure and fish-breeding water were then collected and used to fertilize and water okra and lettuce crops. Two systems were used for the crops (okra and lettuce) tested in an elementary plot design with replicates for each treatment (T1: fish-breeding water alone; T2: river water alone; T3: fish-breeding water combined with manure; T4: river water combined with manure). Morphometric parameters and phenological traits of okra and lettuce crops as well as the total harvest weight and production yield were evaluated and compared between treatments. The results reveal better growth and higher yields (0.67 kg/m2 vs. 0.45 kg/m2) of okra crops that received treatment T1 compared to T2. The best growth and yields of lettuce were obtained with treatments T3 (3.34 kg/m2) and T1 (1.89 kg/m2) compared to T4 (1.23 kg/m2) and T2 (1.20 kg/m2). These results show that fish-breeding water combined with poultry manure can boost okra and lettuce production and would be a real asset to stimulate local agricultural development. Thus, the adoption of such an agro-ecological approach integrating fish farming and animal husbandry could increase local production and provide food of good nutritional quality.

Efficacite des bioinsecticides a base de l’huile essentielle de Cymbopogon schoenanthus (L.) spreng contre les punaises rouges (Dysdercus voelkeri, schmidt) en culture cotonniere au Togo

Currently, the fight against red bugs, a pest of the cotton plant, is limited to the use of synthetic chemical insecticides. Many of the products used are persistent and their high toxicity to human health and the environment is of concern. In the search for alternatives to synthetic chemical insecticides, the aim of this research work was to evaluate the insecticidal potential of aqueous emulsions based on the essential oil of Cymbopogon schoenanthus(L.) against Dysdercus voelkeri, one of the redoubtable pests of cotton plant in Togo. Aqueous emulsions at different concentrations were used in phytosanitary treatments on cotton crop compared to vulgarized binary insecticides (lambdacyhalothrin/profenofos 15/300 gha-1and cypermethrin/acetamiprid 36/8 gha-1). D. voelkeri counts on target plants of each elementary plot revealed that the highest dose of the emulsion (6%) of C. schoenanthus essential oil and the control (vulgarized insecticide)were more effective with low bug population densities of 7.14± 1.46 and 4.86± 1.84 bugs/plant,respectively. On the contrary,the other doses (4 and 2%) of emulsions based on C. schoenanthus essential oil had in their plots respectively 39.57 ± 5.81 and 45.28 ± 3.92 bugs/plant and the control (55.71± 5.23 bugs/plant). Health analysis of the young cotton bolls that fell under the cotton plants revealed that the highest dose of the emulsion (6%) and the control reduced stings by 71.40 and 72.33 % respectively, compared to the control. Stings reduction rates in plots with treatments of 4 and 2% of the emulsion were low with rates of 55.32and22.83%,respectively. These results clearly show that the aqueous emulsion formulated and tested in the study can significantly reduce attacks of these pests. This study shows the possibility of using the essential oil of C. schoenanthus as a raw material in the formulation of biopesticide as an alternative to synthetic chemical insecticides in the control of cotton plant red bugs in Togo.

Mass selection of fonio landraces (Digitaria exilis) grown in Benin: Pathway, homogeneity assessment and genotypes screening

AbstractFonio production is generally in polyvarietal mixture and no improved varieties are available yet. This work proposed a pathway for homogenization and mass selection from 19 accessions previously collected in Benin, to sort best genotypes. From 2015 to 2017, accessions were submitted to homogenization followed by separated conduct of different phenotypes appeared each year. Each material was evaluated on elementary plot of 3 m2. Agro‐morphological data collected were submitted to descriptive and multivariate analyses. Results showed homogeneity and selection effectiveness varied following characters and accessions. Better homogeneity level was obtained on qualitative characters compared to morphometric traits. Selection led to derivative accessions earlier or more productive than their parents. Thus, compared to parents, shortenings of 10%–30% on plant cycle and progress of 10%–70% in yield were recorded for some derivative accessions. On grains colour, 86% of accessions are homogeneous from 70% to 100%. Three groups characterized by earliness, productivity and grains homogeneity were identified. AS19‐1‐1, AS1, AS13‐1, AS2‐1‐1, AS15‐1‐1 and AS18 were sorted genotypes. Multi‐local assessments will be conducted for homogeneous and efficient ideotypes responding farmer's needs.

Agronomic Performances and Nutritional Assessment of Three Sweet Potato Varieties (Ipomoea batatas (L) Lam.) Introduced in an Agro-ecological Zone of Groundnut Basin in Senegal

Aims: To evaluate the agronomic and nutritional performances of three varieties of sweet potato (Kandee, Caromex and Gandiol1) cultivated for the first time in the agro-ecological zone of the groundnut basin in Senegal.
 Study Design: The experiment was arranged in Randomized Completely Block Design.
 Place and Duration of Study: The study was conducted during two growing seasons from April to August 2017 and from October 2018 to February 2019 in Sagna village (Kaffrine, Senegal).
 Methodology: The planting of the cuttings was done with a density of 0.3 x 1 m or 3333.3 cuttings ha-1. Drip irrigation was used and mineral fertilization with 15-15-15 was applied. In each elementary plot, 5 plants were checked monthly for growth and phytosanitary monitoring. The harvest took place at 145 days after planting. The yields and agro-morphological characteristics of the roots were determined as well as their nutritional value and the incidence of bio-aggressor attacks.
 Results: The success percentage of cuttings was 90.1, 90.5 and 88% for Kandee, Caromex and Gandiol1, respectively. The length development of sweet potato stems was variable between the 3 varieties. The Gandiol1 variety with stems longer than 1.6 m was very spread out contrary to Caromex whose average stem length did not exceed 0.5 m. The marketable tuber yields obtained were comparable between the varieties and were 21.5, 22.5 and 13.4 t ha-1 respectively for Kandee, Caromex and Gandiol1. The morphology of the tubers was different in shape (diameter and length) but also in flesh color. Kandee had orange flesh, rich in carotenoids (101.1 mg/kg; P<0.001), Caromex a cream color with carotenes of 43.2 mg kg-1 and Gandiol1 a white flesh. Caromex had the best proportion of dry matter (40.6%; P<0.001) compared to the other varieties. This amount of dry matter was correlated with the marketable root yield (r=0.54; P=0.04) and the carbohydrates amount (r = 0.52; P=0.05). Bio-aggressor incidence on tubers was lower for the Kandee variety (10.3%; P=0.01).
 Conclusion: Sweet potato varieties performed well in the agro-ecological conditions of the groundnut basin and showed comparable agronomic performance. The three varieties can be discriminated on the level of their nutritional quality, particularly on their β-carotene content.

Application of profilograph for evaluation of mechanical tillage of slope lands

In this paper, we analyze a wide range of measurements of the day surface profile of tilled soil in order to substantiate the moving average method for evaluating morphological parameters and studying the influence of the base profile length on the accuracy of the obtained values. The surface roughness of the elementary plot was 4 mm, the surface ridgeness formed by technological furrows was 16 mm, and the slope of the plot was 0.198. The accuracy of the obtained values of roughness and ridgeness of the tilled soil surface depends significantly on the profile length determined by the number of measurements performed. We obtained 5273 data points per one turn of the device on a 6.3 m profile length (1 measurements are made per 1 mm) for the elementary plot. The surface roughness varied from 3, 1 mm to 4, 3 mm, and the ridgeness – 12 ... 21 mm when the number of measurements is from 2000 to 5273. When the measured profile length is about 1.3 m or less (not more 2000 points), the parameters of the tilled soil cover are not considered important. However, they are more critical for ploughed soil than for harrowed soil. On flatter surfaces, the base profile length of 2.5 m may be sufficient to adequately calculate the parameters of the day soil surface.

Selection and genetic parameters for interpopulation hybrids between kouilou and robusta coffee

ABSTRACT Selection of hybrid coffee plants coming from crosses between divergent populations is particularly relevant for the success of breeding programs. This study aimed to outline the best selection strategy in a hybrid population of Coffea canephora var. kouilou and robusta by estimating intrapopulation genetic parameters. Twenty full-sib progenies obtained by North Caroline II were installed in a randomized complete blocks design, with one plant per elementary plot. The following traits were evaluated: vegetative vigor, reaction to rust, plant height, diameter of canopy projection, maturity time, and bean yield. Significant individual genotypic variance and heritability estimates lead to an effective selection. The multi-trait selection index carried out between progenies and at individual level provided 5% and 40% gain, respectively. Thus, intrapopulation selection in a hybrid population is a viable strategy for the selection of superior individuals to compose new crosses and clones for cultivars in the breeding program of C. canephora, even with unbalanced data.

THE EFFECT OF COVER CROPS ON THE CONTENT OF PROTEIN IN GRAIN OF SWEET MAIZE

The study was conducted in the experimental field of the Maize Research Institute Zemun Polje, Serbia, during 2013/14-2014/15. The experiment was established as a block design with four replications. As winter cover crops-CC (factor A) the following plants were grown: CV–common vetch (Vicia sativa L.), FP-field pea (Pisum sativum L.), WO-winter oats, (Avena sativa L.), FK-fodder kale (Brassica oleracea (L.) convar. acephala), two mixture variants of legume crops with oats (CV+WO and FP+WO) and two control treatments: a variant in which the surface was covered with dead organic mulch (DOM) and traditional variant: after ploughing in the fall plot stayed uncovered during the winter (TV). Green biomass of the cover crops was incorporated in the soil, immediately after, half of the elementary plot was infested with bio-fertilizer (BF) - Uniker (mobilizer of nutrients) in an amount of 10 l ha-1 (factor B), which contains the strains of cellulolytic and proteolytic bacteria to support the mineralization of entered crop residues. The seeds of sweet maize ‘ZPSC 421su (FAO 400) were sown at the arrangement of 70 cm between rows and 22 cm between plants in the row (65,000 plants per ha). Preceding crop in both years was winter wheat. The kernel protein content was measured on infrared analyser. The data were processed by ANOVA. The investigated factors (CC and BF) showed significant effect on protein content in sweet maize kernel in both years. As it was expected, the greatest impact on protein content was exhibited in leguminous species grown alone, or in mixtures with oats, particularly in the dry, 2015. Small grains intercropped with legumes obtained higher values of protein content than small grain grown as monocrops.

Low frequency tapping systems applied to young-tapped trees of Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. in Southern Thailand

A declining rubber price and labor shortages in the context of climate variability are problems for rubber smallholders. A low frequency tapping system that may be a solution to these problems was tested in southern Thailand using eight-year-old trees of the RRIM600 clone at the Thepa Research Station, Songkhla province. The experimental design was a randomized complete block with five treatments defined in Table 1 and abbreviated to: T1: S/3 d1 2d/3; T2: S/2 d2; T3: S/2 d3 ET 2.5% Pa1 (1) 8/y (m); T4: S/3 d2 ET 2.5% Pa1 (1) 4/y (m); and T5: S/3 d3 ET 2.5% Pa1 (1) 12/y (m). There were three replications (elementary plot) with 10 trees per treatment in each elementary plot. The results showed that low frequency tapping systems (d3) with stimulation resulted in an equivalent yield in cumulative latex production compared with the other tapping systems and also had higher latex production per tapping. Bark consumption was less in the low frequency tapping systems leading to the possibility of lengthening the economic lifespan of the tapping panels of the tree. A low frequency tapping treatment with stimulation eight times per year induced decreases in the total solids, sucrose and reduced thiol contents; however, the inorganic phosphorus content increased, as is usually seen with the use of ethylene stimulation. The response of rubber trees to a low frequency tapping system should now be tested in the long term.

Do the impact of organic residues on soil quality extend beyond the deposition area under oil palm?

Recycling empty fruit bunches (EFBs) in mature oil palm stands usually consists in distributing them over a limited area representing 3%–10% of the plot. The impact of this practice on soil quality, including soil biodiversity, is not well known at the plot scale. We analysed soil physical, chemical, and biological variables. Five zones were defined around the palm tree to assess spatial heterogeneity due to plant cover and application of organic and inorganic fertilisers. Each zone was analysed separately. Our study revealed marked variations in mineral contents around the palm tree, ranging from deficiency to excess or nutrient imbalance in adjacent zones, particularly in available P and K, Mg and pH. Similar variations in macrofauna were observed both in the litter and the soil. Our results demonstrate that the changes caused by plant cover and applications of fertiliser are mainly limited in space, but that earthworm communities move as a function of variations in nutrient availability or stress associated with EFB deposition over time. The Amacher index, adapted to the soil nutrient status for oil palm, indicated that average mineral fertility at the plot scale was rather good. The average density of soil macrofauna and nematofauna was low compared to other tropical ecosystems, but reference data from Indonesia are lacking. Application of EFBs on the harvest path mainly improved the homogeneity of soil quality within the elementary plot around the palm. However these data did not show that recycling EFB stimulates soil fauna communities or carbon sequestration at the plot scale.

INTERACTION BETWEEN THE MANAGEMENT OF SOIL FERTILITY AND MACROFAUNA REDUCES RUNOFF ON A LIXISOL IN THE NORTH-SUDANIAN ZONE OF BURKINA FASO

SUMMARYA study that aims to assess the impact of the interaction between soil macrofauna and soil fertility management methods on runoff, was conducted in the north-sudanian zone of Burkina Faso on a Lixisol with an average slope of 1.5%. Runoff was measured using a runoff plot of 1.04 m2 and crop yields were measured on the effective area of the elementary plot. Biocide treatments used to control the population of macrofauna have eliminated 95% to 99% of soil macrofauna. Except for urea treatment, the results showed that the presence of macrofauna has led to the reduction of runoff in the other treatments. The absolute contribution of macrofauna to runoff varied between 24.58% and 30.74%. Runoff reduction was higher on soil management based on sorghum straw + urea (71.24% in 2008 and 78.80% in 2009) in the presence of soil macrofauna. We concluded that in cropping systems with low external inputs, stimulating the activity of macrofauna by burying material with high ratio of carbon to nitrogen reduces runoff and thus maintains the potential of farm land.

Yielding capacity of different varieties of winter wheat depending on conditions of its cultivation in the northern steppe of ukraine

The paper presents the results of study of the yielding capacity of different varieties of winter wheat depending on agrotechnical methods of their cultivation in the Northern Steppes of Ukraine. A comparative analysis of the processes of formation of the yield formula elements in growing winter wheat after bare fallow, soybeans and spring barley was carried out. It was established that varietal reaction of the tested varieties to predecessors and the level of mineral nutrition were different. Thus, the highest yield was formed by Zira and Rozkishna varieties. On average, during the years of study, depending on the growing conditions, it varied within 2.80 to 5.12 and 3.03 to 5.82 t/ha respectively.Methods. The study was conducted during 2010-2013 on the experimental farm "Dnipro" of the State Institution Institute of Agriculture of Steppe Zone of NAAS, in the field three-factor experiment, which was laid using the method of successive plots, in a systematic way. The area of the elementary plot was 60 m2 and of accounting plot - 40 m2. Repetition in the experiment: three times.The main objective of the research was to study more advanced agrotechnical efficiency in cultivation of different varieties of winter wheat in the conditions of the Northern Steppe of Ukraine.Results. The research results show that plants of different varieties of winter wheat depending on their varietal characteristics responded differently to their predecessors and the level of mineral nutrition. When sown after bare fallow, Zira and Rozkishna varieties, over the three years of research on average, provided the yields of 5.12 and 5.82 t/ha respectively and the yield index of Zamozhnist variety was 5.03 t/ha. When all the studied varieties were sown after the spring barley, their yields were significantly lower. Thus, on the plots of this predecessor, where N60P60K60 was applied before cultivation with subsequent nourishment in the spring with nitrogen N30 applied on the half-melted soil and N60 applied in the phase of spring tillering, the grain productivity of Zira variety was 3.74 t/ha; Zamozhnist - 3.50 t/ha; Rozkishna - 3.96 t/ha. Also the varietal response of plants to the level of their mineral nutrition in the spring and summer period when growing after soybeans was traced quite clearly. The research helped establish the most effective rate of nitrogen fertilizer. Thus application of N45P45K45 before cultivation and subsequent nourishment of plants with N30 on the half-melted soil in spring followed by application of N30 locally in the spring tillering phase provided the yield of Zira, Zamozhnist and Rozkishna varieties from 3.71 to 4.07 t/ha.Conclusions. When growing winter wheat in the Northern Steppe of Ukraine such varieties as Zira, Zamozhnist and Rozkishna should be sewn after bare fallow and according to the technology that provides application of N30P30K30 during the primary tillage, N30 on the half-melted soil and the local application of N30 in the spring bushing phase, which provides the grain yield within 5.03 to 5.82 t/ha. When growing winter wheat after soybeans the preference should be given to semi-intensive and versatile varieties such as Zira and Rozkishna and they should be grown with application of N45P45K45 during primary tillage, N30 on the half-melted soil and N30 locally in the spring tillering phase. After spring barley it is advisable to grow Rozkishna, winter wheat of a versatile variety, using the technology that provides application of N60P60K60 during the primary tillage, N30 on the half-melted soil and the local application of N60 in the spring tillering phase.

Optimal number of observation, treatment and replication in field experiments

Experimental recognostic trial was carried out in spring barley agrophytocenoses, evaluating data standard error (SE) and mean accuracy (MA%) depending on arranged elementary trial plots, treatment and replication number, their model size. The received experimental data are applicable carrying out all agronomical and biological field trials. Trial field was divided into 222 elementary plots of 13.44 m2. The trial objective was agrophytocenoses of spring barely Roland. Observation number increasing from 2 to 6, trial data accuracy demonstrably increases, while increasing it from 6 to 10 accuracy increases more slowly, and increasing the number of observations from 10 to 30, accuracy almost does not change. Enlarging plot size from 13.44 to 134.4 m2, the accuracy of experimental data increased. However, experimental field was homogeneous enough. Increasing replication number, trial SE regularly decreases independently of the arranged treatment number in the trial. Modelling trial with 40 m2 size plots with 2 to 3 replications, data accuracy reaches 10.2 to 6.2%, so trials can be acknowledged as inaccurate. Increasing replication number from 4 to 6, data accuracy decreases from 4.7 to 2.8%. Increasing replication number to 10, trial accuracy increases to 2.0%. Further increasing replication number from 10 to 37, data accuracy progressively increases from 1.5 to 1.6%. Therefore, carrying out field trials in moderate plots relating to 40 m2, experiments should not have less than 3 to 4 replications. Optimal number of treatments, according to SE and accuracy evaluation, is between 4 and 7. Then the highest accuracy of experimental data is reached. Key words: Elementary plot, number of observation, replication, treatment, recognostic field trial, standard error, data accuracy.

The Development of the Tales of Magic and the Problem of Their Origin

Researchers who traced the origin of the tales of magic back to the times of the formation of the tribal system (V. Propp) or its decay (E. Meletinsky) assumed that tale plots were rather stable. This article aims at demonstrating the development of plot structures and the reflection of new social problems – the weakening relations among kin members and changing forms of marriage. The ancient tales may have been pragmatic works limited to one elementary plot or to simple structures of semantic pairs of elementary plots showing the opposing actions of two acting figures. The process of the formation of artistic tales with complicated structures was not even. Tales of magic and myths are spreading a heterogenous knowledge which they have accumulated.

NEW ARTEMISIA ANNUA HYBRIDS WITH HIGH ARTEMISININ CONTENT

NEW ARTEMISIA ANNUA HYBRIDS WITH HIGH ARTEMISININ CONTENT

Slave-Girl Lost and Regained: Transformations of a Story

A story found in many forms in Arabic has the following basic structure: (1) A man owns a slave-girl. Usually, the man is young and wealthy and the girl both beautiful and accomplished, especially in singing and playing. It is understood that the girl is the man's concubine (as is normal according to traditional Islamic law). (2) The man and the slave-gin love each other. This is not always stated explicitly, but must then be inferred from the rest of the story. (3) The man becomes, destitute. Often this is the man's fault, by spending all his money on his girl. In one version (see nos. 14-15 below in the appendix), it is not his fault but caused by the discontinuation of a regular stipend. (4) The man sells the girl. The initiative may be taken by either. There is a touch of paradox here, for one would expect true lovers to prefer suffering extreme poverty to being separated. Some versions explain it as an act of unselfishness on the part of the man or the girl. (5) The new owner becomes aware of their attachment. (6) He generously returns the slave-girl to her lover. He does not ask his money back and often gives some extras. The sequence (1)-(6) can be further reduced to the following very elementary plot summary: Union/Possession (1+2) Separation/Loss (3+4) Reunion/Repossession (5+6) This is a basic structure of the Relief After Distress genre; it is not surprising that al-Tanukhi (d. 994), author of a collection of stories on this theme, offers many versions. The linking of (re)union with (re)possession and of separation with loss is of course a result of the traditional Muslim system of concubinage. It does not necessarily imply that from a narrative point of view the girl is inferior to the man. On the contrary, morally, intellectually and artistically she is usually the superior partner. Some versions are expanded by complications coming between (4) and (5) or (5) and (6). Exceptionally (see no. 17), a reduced structure is found: a man sells a slave-girl and only afterwards falls in love with her. This may be represented as (1-4-5-6-2). All versions are essentially realistic, without demons, magic or other supernatural elements. The realism is often enhanced by means of details from everyday life, by real place names and names of real-life protagonists, or by providing a chain of authorities for the story. Several clusters of closely related versions can be discerned. The Thousand and One Nights contains two stories of this type (as well as some stories with closely related motifs). Far more versions, some of them virtually identical to those of the Nights, are found in works belonging to polite or elite literary culture, from the ninth century onward. It is likely that the type was around already in the time of al-Madâini (d. ca. 850; see no. 8). The oldest source used here is al-Muhabbar by Muhammad Ibn Habib (d. 860; see no. 2). From a narrative point of view the stories are often rather uninteresting since they lack a human opponent, Fate being the principal adversary. To make up for this, some elaborations enhance the role of Fate, either by introducing the usual unlikely coincidences or by introducing real adversaries, such as is found in the story of al-Hikâyât al-'ajiba (no. 19). An inventory of plot summaries of the versions I have found, with some comments and references, is attached as a lengthy appendix. The authors' sources, often given in the form of a chain of authorities, are omitted here. It is impossible to establish a precise chronological order, and the order in the following presentation is to some extent arbitrary. Mention of historical persons in the story is of course no guarantee for its veracity, and the story may have been invented much later. However, if such persons are relatively obscure, rather than famous, there is a good chance that the story is not much later than the time frame of the person mentioned. …

Relationships between plant and soil water status in five field-grown cotton ( Gossypium hirsutum L.) cultivars

The objective of this study was to evaluate the possibility of using the fraction of transpirable soil water (FTSW) under field conditions, to analyse genotypic differences in plant responses to soil water deficit. Two years of field experiments were carried out on a sandy soil under sub-sahelian conditions in Senegal. Five cotton cultivars ( Gossypium hirsutum L.), with similar phenology but different yield responses to drought, were compared under two irrigation treatments differentiated after flowering. Because of differences in the rainfall pattern during the pre-flowering period, the two years resulted in marked differences in soil water hydration and effective rooting depth. Soil water deficit experienced by the plants in each elementary plot was characterized with FTSW, calculated with volumetric soil water content (measured with a neutron probe) from soil surface to the estimated effective rooting depth. Despite large differences of soil water content between years and irrigation treatments, FTSW was closely related to the predawn leaf water potential measured on the same day. Plant responses to soil water deficit were analysed with leaf water potential ( ψ l), relative water content (RWC), stomatal conductance ( g s), and crop water stress index (CWSI) measured during the crop cycle. Genotypic differences for these plant variables were found on some days, but they were frequently associated with genotypic differences in FTSW. The relationships between plant variables and FTSW, over two years of measurements and contrasting soil water profiles, were adjusted to typical logistic functions, previously used in other species. Leaf water status ( ψ l and RWC), g s and CWSI did not change appreciably until FTSW reached 0.4–0.5. Significant genotypic differences were found in the relationships of RWC and CWSI with FTSW, which allowed the ranking of the five cultivars for dehydration avoidance. The absence of genotypic differences in the relationships between g s and FTSW indicates that the higher dehydration avoidance of one of the cultivars (STAM F) is not linked to stomatal regulation, but probably to osmotic adjustment. Calculation of FTSW from soil water content measurements provided an efficient way to conduct genotypic comparison of plant response to drought in field conditions over two years of contrasted rainfall pattern.