Supporting Cotton Productivity in Côte d’Ivoire through Agronomic Interventions ()
1. Introduction
After achieving a record production of 400,000 tons of seed cotton and a yield of 1400 kg/ha in 1999/2000, the sociopolitical crisis in Côte d’Ivoire led to a sharp decline in production to 145,000 tons and a decrease in yield to 732 kg/ha from 2003/2004 [1]. Since 2010/2011, thanks to the recovery efforts led by the State of Côte d’Ivoire, the stakeholders in the sector, and development partners, cotton cultivation has regained momentum [2]. However, field yields remain well below the pre-crisis level of 1.4 tons per hectare.
This situation is largely due to the misalignment of farming practices with the current context marked by climate change, with planting densities in the field generally being lower or higher than those recommended by research [3].
Moreover, the decline in soil fertility under cotton, characterized by soil acidification, the emergence of new pests and diseases, and prolonged rains at the end of the season promoting regrowth of cotton vegetation and rotting of already mature capsules, represent additional constraints explaining the low yields [3].
In light of the low seed cotton yield observed in the cotton basin, the objective of this study is to develop agronomic strategies that can ensure the sustainability of cotton production.
2. Materials and Methods
2.1. Updating Seeding Densities in Cotton Crops
2.1.1. Monitoring of Yield Trends as a Function of Sowing Densities in Farmer Areas
This activity was carried out by collecting data from farmers on a network of around 500 plots. These plots were selected in June 2023 in 50 localities, with 10 plots per locality (or cotton-growing zone). The plots were selected in proportion to the different decades or sowing periods. Agronomic data were collected on each plot, including the name of the cotton variety sown, the sowing date, the dates of cultivation operations, the sowing density (number of cotton plants/ha) and the seed cotton yield. Simple correlations between sowing density and seed cotton yield obtained by farmers were established for the major cotton companies. A one-factor Analysis of Variance (ANOVA) was also used to determine the optimum sowing densities for farmers.
2.1.2. Evaluation of the Effects of Seeding Densities on Cotton Yields at the Station and on the Observation Post
A trial was set up in Bouaké (Cotton Station) and duplicated on the Observation Posts (PO). The experimental set-up is made of Fisher blocks with four repeats. Only one seeding rate factor was evaluated, with 19 levels (Table 1). The elementary plot is 48 m2, 10 m long and 4.8 m wide. The distance between two blocks is 2 m.
Table 1. Cotton seeding densities compared at the station and the observation posts.
Treatments |
Seeding geometry |
Number of seeds/pocket |
Densities (seeds/ha) |
T1 |
1.0 × 0.40 |
2 |
50,000 |
T2 |
1.0 × 0.30 |
2 |
66,666 |
T3 |
1.0 × 0.20 |
2 |
100,000 |
T4 |
1.0 × 0.15 |
1 |
66,666 |
T5 |
1.0 × 0.10 |
1 |
100,000 |
T6 |
0.9 × 0.40 |
2 |
55,555 |
T7 |
0.9 × 0.30 |
2 |
74,074 |
T8 |
0.9 × 0.20 |
2 |
111,111 |
T9 |
0.9 × 0.20 |
1 |
55,555 |
T10 |
0.9 × 0.15 |
1 |
74,074 |
T11 |
0.9 × 0.10 |
1 |
111,111 |
T12 |
0.8 × 0.40 |
2 |
62,500 |
T13 |
0.8 × 0.30 |
2 |
83,300 |
T14 |
0.8 × 0.20 |
2 |
125,000 |
T15 |
0.8 × 0.15 |
1 |
83,333 |
T16 |
0.8 × 0.10 |
1 |
125,000 |
T17 |
0.7 × 0.25 |
2 |
114,285 |
T18 |
0.7 × 0.20 |
2 |
142,857 |
T19 |
0.7 × 0.15 |
1 |
95,238 |
2.1.3. Observations and Measurements of the Morphological Parameters of Cotton
These observations were made on 10 plants chosen from the three central lines, taking care to leave 2 m at each end. On the first of the three lines, three consecutive plants are chosen by the observer. He then makes a lateral move to reach the second line. On this line, the observer travels 1 linear meter and will choose four successive plants. The same lateral movement is made to reach the third line. At this level, the observer travels another 1 meter and chooses three consecutive plants. This makes it possible to have ten plants per elementary plot.
Plant height (cm): The height of the main stem (HT) is measured from the cotyledonary nodes to the apex of the plant. Measurements are made on the 30th, 60th, 90th day after emergence (DAE) and at harvest.
Number of nodes: Knots are counted at the 30th, 60th, 90th DAE and at harvest.
Number of vegetative and fruiting branches: the count of vegetative and fruiting branches is carried out at harvest. These branches are counted from those between the cotyledonary nodes and the apex of plants.
Average number of green bolls: Of the ten plants labelled in the four central lines, green bolls are counted at the 60th, 75th, 90th and 105th DAE.
Rate of flower bud and green capsule shedding: this operation is performed at the 60th and 90th DAE. It consists of counting the flower buds and fallen green capsules, in order to obtain an indication of the intensity of the losses suffered by the plants, according to the treatments (sowing densities). To do this, after collection, a sorting is carried out to distinguish healthy organs from those that are attacked (with a hole or insect bites). This activity is done every 3 days in the two interlines of the three central lines, leaving 2 m at each of the two edges.
2.1.4. Observations and Measurements of Entomological Parameters of Cotton
These observations are made on the main pests of cotton. On each elementary plot, the count of the different insects is carried out on 30 plants taken in groups of five consecutively on the three central lines, according to the diagonal method. Observations of the cotton entomofauna are made on a weekly basis, from the 35th to the 122nd DAE. These direct observations on plants are supplemented by health analyses of green capsules. Three to six weekly health analyses (ASCV) are carried out on 25 green capsules of the same age (greater than 2 cm in diameter) between the 80th and 115th DAE. The harvested green bolls are carefully dissected with a knife to determine which ones have internal rot and which are healthy. Eventually, the rates of healthy and rotten capsules are determined as well as the number of lepidopteran larvae encountered.
2.1.5. Observations and Measurements of Production Parameters
Boll average weight (BAW): after the bolls have been fully opened, out of five cotton plants belonging to the lateral lines of each of the elementary plots, three bolls in position 1 of the fruiting branches (BF) are harvested. These capsules are collected from the BFs in the low, middle and terminal positions [4]. The BAW is calculated per plot by dividing the total weight of seed cotton by the number of bolls harvested.
Seed cotton yield: the seed cotton is harvested on the three central lines of 8 m long, taking care to leave 1 m of border at the 2 ends of each line.
For plots with 0.7 m row spacing, the harvesting area is: 3 lines × 0.7 m × 8 m = 16.8 m2.
For plots with 0.8 m row spacing, the harvesting area is: 3 lines × 0.8 m × 8 m = 19.2 m2.
For plots with 0.9 m spacing, the harvesting area is: 3 lines × 0.9 m × 8 m = 21.6 m2.
For plots with 1 m spacing, the harvesting area is: 3 lines × 1 m × 8 m = 24 m2.
2.1.6. Statistical Analyses
The data collected were subjected to an analysis of variance (ANOVA) under the R.4.0.1 software, after verification of the normality of the distribution. When a significant difference is observed (p < 0.05) between seeding densities (treatments) for a given parameter, multiple comparisons are made using the Duncan test at the 5% threshold.
2.2. Evaluation of the Effects of Increasing Doses of Zinc Sulphate on the Agromorphological Parameters of Cotton
2.2.1. Experimental Design
This activity is carried out through an experiment at the Cotton Station in Bouaké. The experimental set-up is made of Fisher blocks with four repeats. A single factor corresponding to the dose of zinc sulphate, with eight levels, is evaluated (Table 2). The elementary plot measures 64 m2, 10 m long and 6.4 m wide. The elementary plots are separated by 1 m and the blocks are 2 m apart.
Table 2. Fertilizer treatments including doses of zinc sulfate evaluated.
Treatments |
NPK (kg/ha) |
Urea (kg/ha) |
Zinc sulphate (kg/ha) |
Absolute control (without manure) |
T0 |
0 |
0 |
0 |
Positive control or recommended fertilization |
T1 |
200 (15 JAL) |
50 (45 JAL) |
0 |
Recommended fertilisation (FR) + 150% ZnSO4 |
T2 |
200 (15 JAL) |
50 (45 JAL) |
6 (15 JAL) |
Recommended fertiliser (FR) + 125% ZnSO4 |
T3 |
200 (15 JAL) |
50 (45 JAL) |
5 (15 JAL) |
Recommended fertiliser (FR) + 100% ZnSO4 |
T4 |
200 (15 JAL) |
50 (45 JAL) |
4 (15 JAL) |
Recommended fertiliser (FR) + 75% ZnSO4 |
T5 |
200 (15 JAL) |
50 (45 JAL) |
3 (15 JAL) |
Recommended fertilisation (FR) + 50% ZnSO4 |
T6 |
200 (15 JAL) |
50 (45 JAL) |
2 (15 JAL) |
Recommended fertiliser (FR) + 25% ZnSO4 |
T7 |
200 (15 JAL) |
50 (45 JAL) |
1 (15 JAL) |
2.2.2. Observations and Measurements of the Morphological Parameters of Cotton
These observations are made on 10 plants chosen from the three central lines, taking care to leave 2 m at each end of each line. On the first of the three lines, three consecutive plants are chosen by the observer. He then makes a lateral move to reach the second line. On this line, the observer travels 1 linear meter and will choose four successive plants. The same lateral movement is made to reach the third line. At this level, he travels another 1 meter and chooses three consecutive plants. This will make it possible to have ten plants per elementary plot.
Plant height (cm): The height of the main stem (HT) is measured from the cotyledonary nodes to the apex of the plant. Measurements are made on the 30th, 60th, 90th day after emergence (DAE) and at harvest.
Number of nodes: Knots are counted at the 30th, 60th, 90th DAE and at harvest.
Number of vegetative and fruiting branches: The count of vegetative and fruiting branches is carried out at harvest. These branches will be counted from those located between the cotyledonary nodes and the apex of the plants.
Average number of green bolls: Of the ten plants labelled in the four central lines, green bolls are counted at the 60th, 75th, 90th and 105th DAE.
Rate of fall of flower buds and green capsules (shedding): This operation is performed from the 60th and 90th JAL. It consists of counting the flower buds and green capsules that have fallen off, in order to obtain an indication of the intensity of the temporary loss suffered by the plants, depending on the treatments (sowing densities). To do this, after collection, a sorting is carried out to distinguish healthy or attacked organs (with a hole or insect bites). This activity is done every 3 days in the two interlines of the three central lines, leaving 2 m at each of the two edges.
2.2.3. Observations and Measurements of Production Parameters
Boll Average weight (BAW): After the bolls have been fully opened, out of five cotton plants belonging to the lateral lines of each of the elementary plots, three bolls in position 1 of the fruiting branches (BF) are harvested. These capsules are collected from the BFs in the low, middle and terminal positions [4]. The PMP is calculated per plot by dividing the total weight of seed cotton by the number of bolls harvested.
Seed cotton yield: The seed cotton is harvested on the four central lines of 8 m long while taking care to leave 1 m of border at the 2 ends of each line. The harvesting area is: 4 rows × 0.8 m × 8 m = 25.6 m2.
2.2.4. Statistical Analyses
The data collected are subjected to an analysis of variance (ANOVA) under the R.4.0.1 software, after verification of the normality of the distribution. When a significant difference is observed (p < 0.05) for a given parameter, multiple comparisons are made using the Duncan test at the 5% threshold.
2.3. Management of Revegetation of Cotton Plants at the End of the Cycle
2.3.1. Experimental Design
This activity was conducted at the Bouaké cotton research station, through two (02) trials.
This test was conducted using a Fisher block design with four replicates. The objects compared are described in Table 3.
This test was conducted using a Fisher block design with four replicates. The objects in comparison are described in Table 4.
2.3.2. Observations and Measurements of the Morphological Parameters of Cotton
Observations were made on 10 plants chosen from the four central lines, taking care to leave 2 m at each end of each line. On the first of the three lines, three
Table 3. Defoliant/desiccant rates and application periods in Trial 1.
Treatments |
Defoliant Rates (mL/ha) |
Date d’application (JAL) |
T1 |
0 |
100 |
T2 |
31.3 |
100 |
T3 |
62.5 |
100 |
T4 |
125 |
100 |
T5 |
0 |
120 |
T6 |
31.3 |
120 |
T7 |
62.5 |
120 |
T8 |
125 |
120 |
Table 4. Defoliant/desiccant rates and application periods in Trial 2.
Treatments |
Ethephon Doses (l/ha) |
Date d’application (JAL) |
T1 |
0 |
100 |
T2 |
1 |
100 |
T3 |
2 |
100 |
T4 |
4 |
100 |
T5 |
0 |
120 |
T6 |
1 |
120 |
T7 |
2 |
120 |
T8 |
4 |
120 |
consecutive plants were chosen by the observer. He then makes a lateral move to reach the second line. On this line, the observer travels 1 linear meter and chooses two successive plants. The same lateral movement is made to reach the third line. At this level, he travels another 1 meter and chooses two consecutive plants. The same lateral movement is made to reach the fourth row where three plants are chosen. This made it possible to have 10 plants per elementary plot.
Stands after the demarriage and at the harvest: After the demarriage and at the harvest, the plants on the four central lines of 10 m long were counted by elementary plot.
Plant height (cm): The height of the main stem (HT) was measured from the cotyledonary nodes to the apex of the plant. Measurements were taken on the 30th, 60th, 90th, 120th day after emergence (DAE) and at harvest.
Caulinar growth rate: The caulinar growth rate (VC) of cotton plants, in cm/day, was determined from the curve of the evolution of plant heights [5]. It was calculated by the following formula:
HI: Initial height of the cotton plant
HF: Final Pitch
Number of nodes: Nodes were counted at the 60th, 90th, 120th JAL and at harvest.
Defoliation rate: For each of the plots, live leaf counts were carried out on the 10 randomly selected plants. These counts were conducted prior to application and every seven days after application until the last seed cotton harvest [6]. Thus, the defoliation rate was calculated according to the equation below:
NF2: Final number of live leaves
NF1: Initial number of live leaves
Leaf desiccation rate: For each plot, counts of live leaves (fresh leaves still green) and dried leaves were performed before and every seven days after application until the last harvest of seed cotton [6]. Thus, the desiccation rate was calculated according to the equation below.
NS2: Final Number of Dry Leaves
NS1: Initial Number of Dry Leaves
Number of vegetative and fruiting branches: The count of vegetative and fruiting branches was carried out at harvest. These branches are counted from those between the cotyledonary nodes and the apex of plants.
Average number of green Boll: Out of the ten labelled plants in the four rows
green capsules were counted at the 60th, 75th, 90th and 105th JAL.
Rate of flower bud and green capsule shedding: This operation was performed from the 60th and 90th JAL. It consisted of counting the flower buds and green capsules that had fallen off, in order to obtain an indication of the intensity of the temporary loss suffered by the plants, according to the treatments (sowing densities). To do this, after collection, a sorting was carried out to distinguish healthy or attacked organs (with a hole or insect bites). This activity was done every 3 days in the two interlines of the three central lines, leaving 2 m at each of the two edges.
2.3.3. Observations and Measurements of Production Parameters
Boll opening rate: In each of the elementary plots, all capsules on plants were counted as well as those that were opened. Once these observations were made, the opening rate of the green capsules was determined using the following formula:
N2: number of boll opened
N1: total number of boll
Boll Average weight (BAW): After total opening of the bolls, out of five cotton plants belonging to the lateral lines of each of the elementary plots, three bolls in position 1 of the fruiting branches (BF) were harvested. These capsules were collected from the BFs in the low, middle and terminal positions [7]. The PMP was calculated per plot by dividing the total weight of seed cotton by the number of bolls harvested.
Sanitary analysis of green capsules (ASCV): Three to six weekly sanitary analyses (ASCV) were carried out on 25 greens capsules of the same age (with a diameter greater than 2 cm) per elementary plot between the 80th and 115th DAE. The harvested green bolls were carefully dissected with a knife, to determine which ones had internal rot and which were healthy. Eventually, the rate of healthy and rotten capsules was determined as well as the number of lepidopteran larvae encountered.
Seed cotton yield: The seed cotton was harvested from the four central lines of 8 m long while taking care to leave 1 m of border at the 2 ends of each line. The harvesting area was: 4 rows × 0.8 m × 8 m = 25.6 m2.
2.3.4. Statistical Analyses
The data collected were subjected to an analysis of variance (ANOVA) under the R.4.0.1 software, after verification of the normality of the distribution. When a significant difference is observed (p < 0.05) between seeding densities (treatments) for a given parameter, multiple comparisons are made using the Duncan test at the 5% threshold.
3. Results
3.1. Monitoring of Yield Trends as a Function of Sowing Densities in Farmer Areas
In CIDT zones, sowing density explains a significant part of the yield variations (R2 = 0.1884; r = -0.434; p = 0.000) (Figure 1). The best yields were observed with densities between 30,000 and 40,000 plants/ha (Figure 2).
A weakly positive and non-significant relationship was observed between yield and seeding density in COIC (R2 = 0.0033 r = 0.058 p = 0.458) (Figure 3). However, the highest yield was given by seeding densities ranging from 60,000 to 80,000 plants/ha (Figure 4).
The analyses revealed a negative and significant relationship between yield and seeding density in the SECO zone (R2 = 0.0513; r = -0.226; p = 0.035) (Figure 5). Seeding rates between 60,000 and 90,000 plants/ha yielded the best yields (Figure 6).
A positive and significant relationship between yield and seeding density in the
Figure 1. Relationship between yield and sowing density in CIDT zones.
Figure 2. Yields as a function of sowing densities in CIDT zones.
Figure 3. Relationship between yield and sowing density in COIC areas.
Figure 4. Yields as a function of sowing densities in COIC areas.
Figure 5. Relationship between yield and sowing density in the SECO zone.
Figure 6. Yields as a function of sowing densities in the SECO zone.
Ivory Cotton zone R2 = 0.0874; r = 0.296; p = 0.001 was observed (Figure 7). Increasing seeding density would lead to an increase in yield. The best yields were given by densities between 80,000 and 100,000 plants/ha (Figure 8).
Figure 7. Relationship between yield and sowing density in the Ivory Cotton zone.
Figure 8. Yields as a function of sowing densities in the Ivory Cotton zone.
3.2. Assessing the Effects of Seeding Densities on Cotton Yields
3.2.1. Effects of Seeding Density on Growth and Production Parameters
The growth and production parameters at the different sites as a function of seeding densities are presented in Table 5.
On the Seguela PO, the best yield was obtained with the low sowing densities based on spacings of 90 to 100 cm between rows and 15 to 30 cm between pockets.
At the Nambingué PO, it was the densities based on a spacing of 90 to 100 cm between the rows and 10, 15 and 40 cm on the row at a rate of 1 or 2 plants per pocket that gave the best yields.
At the Boundiali PO, the high densities with cotton rows spaced 70 cm apart and spacings of 15 and 25 cm between the plants, unmarried to 1 or 2 plants/pocket which were better.
Finally, in Bouaké, the best yields were obtained with sowing densities based on spacings of 80 and 100 cm between rows and 10 to 20 cm between pockets, unmarried to 1 or 2 plants/pocket.
Table 5. Growth and production parameters at different sites as a function of sowing densities
Sites |
Densities (geometry) |
HREC |
CC (nb/plt) |
STD |
PMC |
RDT |
PO Séguéla |
74,074 (90 cm × 15 + 1Pl) |
133 |
12 |
51,250 |
6.450 |
2812 |
66,666 (100 cm × 30 + 2Pl) |
125 |
15 |
41,812 |
6.425 |
2760 |
66,666 (100 cm × 15 + 1Pl) |
145 |
13 |
36,750 |
6.650 |
2646 |
PO Nambingué |
55,555 (90 cm × 40 + 2Pl) |
105 |
05 |
31,875 |
4.45 |
1018 |
66,666 (100 cm × 15 + 1Pl) |
106 |
04 |
40,697 |
6.20 |
854 |
111,111 (90 cm × 10 + 1Pl) |
94 |
03 |
53,611 |
5.77 |
821 |
PO Boundiali |
142,857 (70 cm × 20 + 2Pl) |
132 |
16 |
54,642 |
5.48 |
1398 |
114,285 (70 cm × 25 + 2Pl) |
127 |
15 |
56,071 |
5.56 |
1339 |
83,333 (80 cm × 15 + 1Pl) |
131 |
14 |
43,125 |
5.46 |
1236 |
Bouaké Cotton Station |
83,333 (80 cm × 15 + 1Pl) |
117 |
13 |
46,093 |
6.73 |
1983 |
100,000 (100 cm × 20 + 2Pl) |
104 |
12 |
39,562 |
6.70 |
1813 |
125,000 (80 cm × 10 + 1Pl) |
103 |
09 |
50,625 |
6.55 |
1797 |
H90: Height 90 JAL, CC: Capsular Load (Average Number of Capsules/Plant), STD: Stand at Harvest, PMC: Average Capsular Weight, RDT: Yield.
3.2.2. Effects of Seeding Density on Health Parameters
At the experimental station (Bouaké) and at the OP (Seguela), sowing density had no significant effect on pest attacks (Table 6).
3.3. Improvement of Cotton Productivity by the Addition of Zinc Sulphate
Effects of Zinc Sulphate doses on Growth and Production Parameters
Analyses of the campaign data (Table 7) indicate that the optimal rate would be 2 kg/ha ZnSO4/ha. This dose generated a gain of about 35,100 CFA francs/ha.
3.4. Management of Revegetation of Cotton Plants at the End of the Cycle
3.4.1. Effects of Ethephon Applied as a Defoliant and/or Desiccant on Agromorphological Parameters
The different doses of ethephon reduced the growth rate and increased the defoliation rate and the capsule opening rate, respectively. The rate of 4 L/ha at
Table 6. Effects of seeding density on health parameters.
Sites |
|
Cap.S (%) |
Cap.P (%) |
Cap.T (%) |
BEM/30 plts |
JASS/30 plts |
Bouake Cotton Station |
AVG. |
22.80 |
1.71 |
0.35 |
13.5 |
46.4 |
MIN. |
2 |
0 |
0 |
1 |
1 |
MAX. |
25 |
11 |
4 |
84 |
182 |
P |
0.866 |
0.883 |
0.455 |
0.933 |
0.578 |
SIG. |
NS |
NS |
NS |
NS |
NS |
PO Seguela |
AVG. |
21.45% |
2.44% |
0.97% |
60.95 |
108.3 |
MIN. |
0% |
0% |
0% |
28 |
49 |
MAX. |
25% |
25% |
7% |
118 |
184 |
P |
0.684 |
0.777 |
0.216 |
0.612 |
0.757 |
SIG. |
NS |
NS |
NS |
NS |
NS |
Cap. S: Healthy green capsule rate, Cap. P: Rate of rotten green capsules, Cap. T: Rate of green bolls with holes, BEM: Average number of whiteflies (Bemisia Tabaci/30 plants), JASS: Average number of jasside/30 plants.
Table 7. Parameters of growth, production and financial profitability of fertilizers supplemented with ZnSO4.
Fertilizers |
HREC |
PMC |
GDR |
GAIN/LOSS |
RevADD |
T0 |
79.50 |
5.08 |
742.17 |
−97.37 |
−216,798 |
FR |
97.23 |
5.75 |
1464.83 |
0.00 |
− |
FR + 1ZN |
106.24 |
6.04 |
1484.36 |
1.32 |
6000 |
FR + 2ZN |
108.36 |
6.64 |
1582.02 |
7.41 |
35,100 |
FR + 3ZN |
109.86 |
6.13 |
1509.67 |
2.97 |
13,500 |
FR + 4ZN |
102.86 |
5.84 |
1471.34 |
0.44 |
2100 |
FR + 5ZN |
110.16 |
5.71 |
1451.81 |
−0.90 |
−3900 |
FR + 6ZN |
108.73 |
5.28 |
1393.22 |
−5.14 |
−21,600 |
HREC: Harvest height, SML: Average capsular weight, RDT: Yield RevADD: Additional income.
100 days after emergence appears to be optimal for its effects on both growth (Table 8) and production (Table 9) parameters.
3.4.2. Effects of Diuron Applied as a Defoliant and/or Desiccant on
Agromorphological Parameters
The different doses did not significantly alter the growth rate. However, they increased the defoliation rate and the opening rate of the capsules. The rate of 62.5 ml/ha applied at 100 days after emergence appears to be optimal for its effects on both development (Table 10) and production (Table 11) parameters.
Table 8. Growth parameters by ethephon rates and application dates.
Defoliants |
VCC (cm/d) |
TxDef (%) |
TxOC (%) |
T0 |
0.65 |
- |
- |
1 l/ha × 100 JAL |
0.06 |
57 |
85 |
2 l/ha × 100 JAL |
0.04 |
50 |
90 |
4 l/ha × 100 JAL |
0.02 |
54 |
90 |
1 l/ha × 120 JAL |
0.09 |
64 |
70 |
2 l/ha × 120 JAL |
0.06 |
54 |
71 |
4 l/ha × 120 JAL |
0.03 |
65 |
83 |
VCC: Growth Rate, TxDef: Defoliation Rate, TxOC: Green Capsule Open Rate.
Table 9. Production parameters according to the doses and dates of application of ethephon doses.
Defoliants |
PRCT (%) |
RDT (kg/ha) |
GAIN (%) |
T0 |
32.05 |
1021 |
- |
1 l/ha × 100 JAL |
78.26 |
1670 |
39 |
2 l/ha × 100 JAL |
80.95 |
1738 |
41 |
4 l/ha × 100 JAL |
82.26 |
2021 |
50 |
1 l/ha × 120 JAL |
40.22 |
1426 |
28 |
2 l/ha × 120 JAL |
38.18 |
1602 |
36 |
4 l/ha × 120 JAL |
45.22 |
1563 |
35 |
PRCT: Early production, RTD: Seed cotton yield.
Table 10. Growth parameters by diuron dose and application dates.
Defoliants |
VCC (cm/d) |
TxDef (%) |
TxOC (%) |
T0 |
0.38 |
- |
- |
31.3 ml/ha × 100 JAL |
0.34 |
51.48 |
40.00 |
62.5 ml/ha × 100 JAL |
0.31 |
52.66 |
58.89 |
125 ml/ha × 100 JAL |
0.32 |
60.84 |
56.39 |
31.3 ml/ha × 120 JAL |
0.35 |
59.00 |
51.24 |
62.5 ml/ha × 120 JAL |
0.37 |
43.76 |
34.52 |
125 ml/ha × 120 JAL |
0.36 |
56.52 |
27.92 |
VCC: Growth Rate, TxDef: Defoliation Rate, TxOC: Green Capsule Open Rate.
4. Discussion
The survey in a farmer environment and the results of experiments in a controlled environment (PO and station) have shown a variation in the best densities depending on the production areas. Thus, in the southern part of the cotton basin,
Table 11. Production parameters according to the rates and dates of application of doses of diuron + Thidiazuron.
Defoliants |
PRCT (%) |
GDR (kg/ha) |
GAIN (%) |
T0 |
59.57 |
1904 |
- |
31.3 ml/ha × 100 JAL |
61.16 |
2211 |
13.91 |
62.5 ml/ha × 100 JAL |
67.40 |
2330 |
18.06 |
125 ml/ha × 100 JAL |
64.50 |
2275 |
16.31 |
31.3 ml/ha × 120 JAL |
59.73 |
2062 |
07.67 |
62.5 ml/ha × 120 JAL |
56.94 |
2197 |
13.33 |
125 ml/ha × 120 JAL |
60.46 |
2148 |
11.36 |
PRCT: Early production, RTD: Seed cotton yield.
it is the low densities that give the best yields. This could be explained by an area where the soils are still much fertile [8] with significant rainfall (> sometimes to 1200 mm) [9]. In this production area of the cotton basin, cotton plants have a great growth and these low densities allow a good realization of sowing and fertilization operations, given the short distance between pockets.
However, in the northern part of the cotton basin, high densities seem to be better. This high density can be explained by a less productive environment [8], [9] and so producers use these high densities in order to cover the soil and create a micro-climate conducive to the development of cotton plants. The results of the survey and experiments showed an influence of sowing densities on yields. These results confirm the work of [10].
The results of the study on the supplementation of the bottom fertilizer (200 kg/ha of mineral fertilizer with an alcohol content of 15-15-15+6S+1B) with zinc sulphate in cotton production indicated that the dose of 2 kg/ha of ZnSO4/ha resulted in the best yield. This dose generated a gain of about 35,100 CFA francs/ha. This positive effect of zinc input could be explained by the deterioration in the level of fertility (in major, secondary and trace elements) of the soils of the cotton basin. These soils are cultivated continuously without any significant input of organic matter or return of crop residues. These results are consistent with those of [11]-[13] on coffee and cotton. They showed that the contribution of zinc in fertilization played an important role in fruit set and retention, as well as in fruit yield and plant quality. These results are consistent with those of [14] who also observed that foliar application of zinc improved cotton growth parameters and yield under stressed conditions.
The study on the management of vegetation resumption at the end of the cycle showed that the application of 4 l/ha of Ethephon and 62.5 ml/ha of Diuron at 100 days after emergence improves defoliation and capsule opening for better management of vegetation recovery at the end of the season. The results of our work are contrary to those of [15] who showed that aggressive defoliation treatment decreased defoliation and increased desiccation, but did not influence yield or cotton fiber quality. This difference in the results could be explained by the type of molecule used as a defoliant.
5. Conclusions
The survey in a farmer environment and the results of experiments in a controlled environment have highlighted a variation in good densities depending on the production areas. Thus, low densities are adapted to the southern part, while in the northern part, high densities seem to be better.
Analysis of data from the 2023-2024 campaign indicated that the optimal dose of zinc sulphate would be 2 kg/ha ZnSO4/ha. This dose generated a gain of about 35,100 CFA francs/ha.
Concerning the management of cotton revegetation at the end of the cycle, the dose of 4 l/ha of ethephon applied 100 days after emergence seems to be optimal, for its effects on both growth and production parameters. The dose of 62.5 ml/ha of diuron applied at 100 days after emergence appears to be optimal, for its effects on both development and production parameters.