Rev. Fac. Agron. (LUZ). 1999, 16: 463-475

Effect of four tillage methods and two forms of urea placement in an ultisol of savanna on vegetative and flowering traits of three sesame cultivars, Sesamum indicum L.

Efecto de cuatro métodos de labranza y dos formas de colocación de urea en un ultisol de sabana sobre caracteres vegetativos y reproductivos de tres cultivares de ajonjolí

Recibido el 03-10-1997 l Aceptado el30-11-1998
1. This work was supported by Project CI-3-0601-0705/95-97 from the Consejo de Investigación, Universidad de Oriente, Maturín, Venezuela under the responsibility of the first author.
2. Departamento de Agronomía, Escuela de Ingeniería Agronómica, Núcleo de Monagas, Universidad de Oriente, Maturín. Fax (091) 415101. E-mail: jmnatera@telcel.net.ve
3. Postgrado Agricultura Tropical, Núcleo de Monagas, Universidad de Oriente. Tele-Fax (091) 417749.

Abstract

Resumen

El presente trabajo tuvo como objetivo principal determinar el efecto de cuatro métodos de labranza y la forma de aplicación del reabono nitrogenado (urea) sobre cuatro caracteres vegetativos y uno reproductivo de tres cultivares de ajonjolí. El experimento se llevó a cabo en la Estación Experimental de Sabana de la Universidad de Oriente, en un suelo francoarenoso. El diseño estadístico utilizado fue el de parcelas divididas con arreglo sistemático de los tratamientos aplicados a las parcelas principales, estando constituidas estas por cuatro métodos de labranza (ML): a) Cincel (C): un pase de arado de cincel 30 días antes de la siembra y un pase de rotativa un día antes de la siembra; b) Rastra (R): tres pases de rastra a los 30, 15 y un día antes de la siembra (método convencional); c) Labranza mínima (LM): un pase de rotativa un días antes de la siembra y d) Cincel + Rastra: un pase de arado de C 30 días antes de la siembra y tres pases de R a los 30, 15 y un días antes de la siembra. Las subparcelas estuvieron constituidas por un arreglo factorial de tres cultivares (Cu): `Glauca', `Acarigua' y `Blanca' y dos formas de colocación de urea (FCU), 200 kg/ha 30 días después de la siembra: bandas enterrada y superficial, para un total de 24 tratamientos con tres repeticiones. Se aplicó una dosis de 500 kg/ha de 12-24-12 al momento de la siembra. El control de malezas se realizó aplicando Dual, Linurex y Gramoxone a razón de 2,0; 0,5 y 3,0 L/ha respectivamente un días después de la siembra, en todos los tratamientos. Los resultados indicaron que no se encontró ningún efecto significativo para la FCU y ninguna de sus interacciones con ML y Cu. Las mayores altura de planta (AP) y longitud efectiva de carga (LEC) se registraron en los ML de C y R para los 3 Cu, mientras que la menor altura de la primera cápsula (APC) se presentó en los ML de C+R y LM para `Glauca' y `Acarigua' y en C+R para `Blanca', el mayor diámetro del tallo (DT) se presentó en R para `Glauca', C y R para `Arawaca' y C para `Blanca'. En cuanto a los Cu, la mayor AP se encontró en `Glauca', la menor APC y el mayor DT en `Blanca', la mayor LEC en `Acarigua'. El Cu con la floración mas precoz fue `Blanca' y el más tardío `Glauca', para los ML, las plantas fueron mas precoces en R y mas tardías en LM.
Palabras clave: Métodos de labranza, colocación de urea, ajonjolí, Sesamum indicum, cultivares

Introduction

The effect of tillage methods on the sesame crop in savannas of Monagas and Anzoátegui States (Vene-zuela) is not well known. The savanna soils are generally poor in fertility, with a low cationic exchange capacity and a low water retention. According to Millán et. al. (15) land preparation is an essential component in the establishment and development of the crops and also, it is a vital part in the integrated pest and disease management. With a good soil preparation, the destruction of weeds is achieved; and usually diseases and insect pests are destroyed. While, Mazzani (12) indicated that reduced dimensions of sesame seeds and slow plant growth in the first weeks after sowing require a perfect soil preparation and the soil has to be finely crumbled.

Sánchez (22) reported that the soil for sesame crop must be well pulverized according its very small seed size and its advisable one plowing at 20 cm of depth and two harrow passes. The main objective of the present work was to determine the effect of four tilla-ge methods and the best form of placement of urea 30 days after sowing on four vegetative characters and a reproductive one in three sesame cultivars.

Materials and methods

The present work was carried out at the Estación Experimental de Sabana de la Universidad de Oriente, in Jusepín, Monagas State, located at 09º 41' 33'' NL and 63º 28' 00'' WL with a height of 174 m under sea level, an annual precipitation of 1,050 mm and annual mean temperature of 27.3 ºC Martínez (11). Evaluation was conducted in the rainy season in a sandy loam soil. The statistical design was a split-plot with special arrangement of treatments assigned to the main plot, being four tillage methods: a) chisel: a pass of chisel plow 30 days before sowing and a pass of rotary cultivator one days before sowing; b) harrow: three passes of harrow at 30, 15, days plus one day before sowing (conventional method); c) minimum tillage: a pass of rotary cultivator one day before sowing and d) chisel + harrow: a pass of chisel 30 days before sowing and three passes of harrow at 30 and 15 days plus one day before sowing. The subplots were constituted by a factorial arrangement of three cultivars viz., `Glauca', `Acarigua' and `Blanca' and two forms of urea placement, 200 kg/ha 30 days after sowing: banded into the soil and superficial, for a total of 24 treatments with three replications. The analysis of conventional variance was carried out, detecting differences among treatments by Duncan's multiple range test. The level of probability was 10 %. For the case of F's, high values of the tillage methods, their means only were reported without the application of the Duncan's test.

A dose of 500 kg/ha of 12-24-12 was applied at sowing. The weed control was carried out applying Dual, Linurex and Gramoxone at 2.0; 0.5 and 3 L/ha, respectively one days after sowing, in the treatments. Each experimental unit was constituted by three rows of 5 m. The space was 0.70 m in-row and 0.05 m intra-row. Twenty plants of the central row were selected to determine the vegetative characters, viz, plant height, height to first capsule, effective length of loading and stem diameter at 10 cm of the soil. The reproductive trait, number of flowering plants at the 40 DAS, was recorded and it was expressed in percentage.

Results and discussion

Plant height (cm). The analysis of variance showed significant differences among the cultivars and also for the interaction cultivars × tillage methods. The coefficient of variation was 6.41 %. The table 1 shows the Duncan's test for this character. The biggest plant height in all the cultivars was registered in the chisel and harrow treatments. The plant height was smaller in the treatments of minimum tillage and chisel+harrow. For the cultivars, the biggest plant height was showed by `Glauca' in all the ti-llage methods, although `Acarigua' presented a plant height statistically similar to `Glauca' in chisel+harrow and minimum tillage.

The sesame seed is small. The soil preparation should be carried out in a such form so that a good sowing bed can be produced for helping seed germination and later seedling deve-lopment. The results indicated that a better plant development is detected when a single tillage implement was applied. The combination of chisel with the harrow had a negative effect in the plant height; similar results minimum tillage. Different results were reported by González (6) working in the savanna of Jusepín, he found that highest plants of sesame cv. `Arawaca' were obtained with a pass of chisel plow plus three only passes of harrow, and a pass of disc plow plus three passes of harrow in comparison with four passes of harrow. Peña (18), carried out an experiment in a silt loam soil in the Colonia Agrícola de Turen, Portuguesa State, Venezuela, and he found that the highest plants of sunflower cv. `M-734' at 30 days after sowing occurred under the system of minimum tillage fo-llowed by the treatment of 3 harrow passes, the smallest plants were achieved under the system with chisel plow. At 90 days, the minimum tillage and three harrow passes had similar means but higher than chisel plow. The differences among these trials could be attributed to different soil textures and/or the use of different crops. On the other hand, Heilman (7), found that in row chiseling increased the height of the cotton plant in comparison to non-chiseled plots in a clay soil. Lindsay et al. (9) carried out two trials in a clay soil and they found that the conventional tillage produced corn plants taller than non-tillage, and minimum tillage.

Table 1. Means for plant height (cm) of three sesame cultivars, Sesamum indicum L. under four tillage methods in the savanna of Jusepín, during the rainy season.

† Duncan's multiple range test at the 10% level of probability. a, b, c, Means followed by the same letters are not significantly different. Uppercase letters for vertical comparisons, lowercase letters for horizontal comparisons.

It has reported in other experiments an increment of the plant height with zero and minimum tillage. Ojeniyi (16), studied the effect of zero tillage and also the effect of 1, 2, and 3 passes of a disc plow on the growth of two corn cultivars on 3 places in the Southern Guinea savanna zone of Nigeria and he found that the non-tilla-ge and two passes of the disc plow produced a greater plant height than 3 passes of the disc plow. Fadayomi (4) in Nigeria found that the plant height of the cowpea cv. `Ife Brown' was significantly larger in the non-tillage system instead of the conventional tillage system. Different results were reported by Hesterman et. al. (8), who found discovered that the plant height of corn was greater for conventional tillage than non-tillage system. Sharma et. al. (24), found that in a clay loam soil, the conventional tillage increased significantly corn plant height about 42% as compared with no tillage, whereas for the mungbean Vigna radiata cultivated in two types of soil: clay loam and sandy loam, the conventional tillage increased the plant height 18% as averaged over two sites and two years in comparison with no tillage. Sharma (23) reported in a two year field experiment that the plant height of fodder oats was significantly lower under minimum tillage than under reduced or conventional tillage.

On the other hand, in other experiments, plant height differences have not been reported for different crops among the different tillage systems. Barrón-Contreras et. al. (3), did not find significant differences in the plant height of corn and French bean due to the tillage systems evaluated (conventional, semi-conventional, minimum and zero tillage). Aulakh and Gill (2) found in field trials carried out during 1984-87 in acid clay soils that the plant height of wheat cvs. `Whydah' and `Hornbill' was not a-ffected by tillage treatments: non-tilla-ge, minimum tillage, conventional disc harrowing + cultivation, deep plowing, deep chiseling, late harrowing and straw removal. Al-Darby (1), did not find significant differences in the corn plant height cultivated in two soil types, a silt loam and a sandy loam during 1982-84 under different tillage systems: tillage plant, chisel, no tillage and conventional mouldboard tillage. Faungfupong and Sakhunkhu (5), reported that the corn plant height was similar for the four tillage types a-pplied including zero tillage, conventional tillage and minimum tillage.

In relationship to cultivars, similar results were reported by Méndez-Natera et. al.. (13), who did not find significant differences for the plant height in the cultivars `Glauca' and `Acarigua' with a general mean of 165.2 cm, while Rattia (20), found that `Glauca' and `Acarigua' had plant heights of 133.1 and 114.6 cm respectively, in the Mesa de Guanipa, Anzoátegui State. Milano (14), found plant heights of 133.4 and 100.8 cm respectively, for the same cultivars in the savanna of Jusepín, Monagas State, and low values in comparison with those obtained with this experiment.

Non significant effects of the form of urea placement at 30 days after so-wing was found on the plant height. Similar results were obtained by Reeves et al. (21) but working with corn, he found that nitrogen fertilization applied at the moment of sowing both banded into the soil or banded superficially improved the corn plant growth, irrespectively of the tillage systems (conventional and conservation) in two soil types viz., silt loam and sandy loam. Faungfupong and Sakhunkhu (5), found that fertilizer application methods of N and P, including broadcasting and four different methods of banding did not differ significantly in their effects on all corn plant characters recorded. However, Marcano and Ohep (10) found that plant height of corn had significant di-ferences for the interactions year × form of urea application and methods of soil preparation × form of urea application.

Height to first capsule (cm). The analysis of variance indicated significant differences between the cultivars and the interaction cultivars × tillage methods. The coefficient of variation was 8.36%. Table 2 shows the Duncan's test for this character. The smallest height to first capsule was presented in the tillage methods chisel+harrow and minimum tillage in the cultivars `Glauca' and `Acarigua' and also in chisel+harrow for `Blanca'. In relation to cultivars, the smallest height to first capsule was registered by `Blanca' in all the tillage methods, although cultivar `Acarigua' had a height to first capsule statistically similar to `Blanca' in minimum tillage.

The height to first capsule followed a similar trend to that observed in the plant height, suggesting that, these two characters were highly correlated and that the different tillage systems affected similarly both characters. In relation to cultivars; `Blanca' had the smallest height to first capsule, followed by `Acarigua', while `Glauca' had the biggest height. Similar results were reported by Méndez-Natera et al. (13), Rattia (20) and Milano (14), who found that cultivar `Acarigua' had a smaller height to first capsule that `Glauca'.

Effective length of loading (cm). The analysis of variance indicated significant differences between cultivars and the interaction cultivars × tillage methods. The coefficient of variation was 9.49 %. Table 3 shows Duncan's test for this character. The biggest effective length of loading of all the cultivars was registered in the chisel and harrow treatment, being smaller the effective length of loading in the treatments of minimum tillage and chisel+harrow. Acording to cultivars, the biggest effective length of loading was for `Acarigua' all the evaluated tillage methods. The effective length of loading followed a different trend the plant height and height of first capsule according to cultivars, but similar trend in relation to tillage systems.

Table 2. Means of height to first capsule (cm) of three sesame cultivars, Sesamum indicum L. under four tillage methods in the savanna of Jusepín, during the rainy season.

† Duncan's multiple range test at the 10 % level of probability. a, b, c: Means followed by the same letters are not significantly different. Uppercase letters for vertical comparisons, lowercase letters for horizontal comparisons.

Similar results obtained in this experiment have been reported by other researchers. Méndez-Natera et al. (13), indicated that `Acarigua' had the biggest effective length of loading with 100.9 cm in a experiment with four sesame cultivars where cultivar `Glauca' was included, whereas from the data of Rattia (20), the effective length of loading for `Acarigua' and `Glauca' was 58.5 and 30.5 cm, respectively, while Milano (14) reported va-lues of 76.3 and 71.4 cm, respectively for these cultivars.

Stem diameter (cm). The analysis of variance indicated significant differences for the cultivars and the interaction cultivars * tillage methods. The coefficient of variation was 9.40 %. Table 4 shows the Duncan's test for this character. The biggest stem diameter was obtained in chiseling and harrowing for `Acarigua', in harrowing for `Glauca' and in chiseling for `Blanca' indicating a differential behaviour of the cultivars to the different tillage systems being smaller the stem diameter in the treatments of minimum tillage and chisel+harrow.

The response of the stem diameter to different tillage systems was not very clear in sesame and other crops. Lindsay et. al. (9), reported in corn that conventional tillage produced plants with more stem dry matter that minimum tillage and zero tillage. Fadayomi (4), found that the stem circunference of the cowpea cultivar `Ife Brown' was significantly bigger in the non-tillage plots than in the conventional tillage ones in Nigeria, while Ortolani et. al. (17), in field trials with corn cv. `HDM 7974' reported that the stem diameter was significantly greater in the methods of conventional tillage using plow, disc and harrow and direct drilling with use of a rotary cultivator with 19.7 and 19.3 mm respectively than other treatments viz.

Table 3. Means for the effective length of loading (cm) of three sesame cultivars, Sesamum indicum L. under four tillage methods in the savanna of Jusepín, during the rainy season.

† Duncan's multiple range test at the 10% level of probability. a, b, c: Means followed by the same letters are not significantly different. Uppercase letters for vertical comparisons, lowercase letters for horizontal comparisons.

Table 4. Means for the stem diameter of three sesame cultivars, Sesamum indicum L. under four tillage methods in the savanna of Jusepín, during the rainy season.

† Duncan's multiple range test at the 10% level of probability. a, b, c: Means followed by the same letters are not significantly different. Uppercase letters for vertical comparisons, lowercase letters for horizontal comparisons.

Subsoiler+heavy disc harrow, heavy disc harrow only and direct drilling.

According to Table 4, for the cultivars, the biggest stem diameter was for `Blanca' in all tillage methods, although `Glauca' had a stem diameter statistically similar to `Blanca' in harrowing. Milano (14) reported values of 1.02 and 0.73 cm for cultivars `Glauca' and `Acarigua' respectively.

Percentage of blooming at 40 days after sowing. The analysis of variance indicated significant differences between cultivars. The coefficient of variation was relatively high (25.29 %).

Figure 1.A indicates that percentage of blooming at 40 days after sowing was in the following order: harrow > chisel > chisel+harrow > minimum tillage with 75.44; 70.50; 66.83 and 52.22%, respectively. Similar results but in corn have been reported by Hesterman et. al. (8), they indicated that corn silking occurred earlier in conventional tillage than in no tillage plots at both locations in both years in 33 corn hybrids cultivated in two locations (18 hybrids in East Lansing and 15 hybrids in Kellogg Biological Station during 1985-86). Al-Darby (1) reported that the days from sowing to 50 % silking of corn plants for non-tillage systems, were significantly delayed by 2-3 and 4 days for the silt loam and loamy sand soils, respectively, in comparison with other tillage systems (tillage plant, chisel and conventional mouldboard). Philbrook (19), reported that conservation tillage delayed maturity of the soybean plants in comparison with conventional tillage. Different results to those obtained in this experiment were reported by Faungfupong and Sakhunkhu (5), who found that zero tillage caused corn plants to flower earlier than conventional tillage practices.

Cultivars figure 1.B shows Duncan's test for the percentage of blooming at 40 days after sowing. The earlier cultivar was `Blanca' followed by `Acarigua'. The later cultivar was `Glauca'. Similar results were reported by Méndez-Natera et al. (13), they indicated that the earlier flowering cultivar was `Acarigua' in comparison with `Glauca' (35.4 and 39.9 days at 50% of flowering plants, respectively) and Milano (14), found values of 33.0 and 41.0 days to 50 % of blooming for `Acarigua' and `Glauca', respectively.

Figure 1. Means for the percentage of flowering plants at 40 days after sowing of three sesame cultivars (Sesamum indicum L.) under four tillage methods in the savanna of Jusepín, Monagas State, during the rainy season. (1.A) Effect of the tillage methods and (1.B) Effect of the cultivars.

Conclusions

The form of urea placement at 30 days after sowing, banded into the soil or in superficial bands did not affect the characters studied, as well as they did not have significant interactions with tillage methods and/or sesame cultivars.

The largest plant height and the effective length of loading for all cultivars were obtained by the chisel and harrow tillage methods. The lar-gest plant height was obtained by `Glauca' in all tillage methods. `Acarigua' had a similar plant height to registered by `Glauca' in the chisel+harrow and in minimum tillage. The largest effective length of loading was showed by `Acarigua', for all the tillage methods evaluated.

The smallest height to first capsule was found with tillage methods of chisel+harrow and minimum tillage for `Glauca' and `Acarigua' and in chisel+harrow for `Blanca'. According to cultivars, the smallest height to first capsule was registered by `Blanca' for all the tillage methods. `Acarigua' had a similar height to first capsule to that of `Blanca' with the minimum tillage method.

The largest stem diameter was obtained by chiseling and harrowing for `Acarigua' and by `Glauca' with horrow and by `Blanca' with chisel. This may be are indicating a differential behaviour of the cultivars for the different tillage systems. The largest stem diameter was demostrated by `Blanca' for all the tillage methods. `Glauca' had a similar stem diameter to `Blanca' with harrowing.

The percentage of blooming at 40 days after sowing was 75.44; 70.50; 66.83 and 52.22 % for harrow; chisel; chisel+harrow and minimum tillage, respectively. The earlier cultivar to blooming was `Blanca', followed by `Acarigua'. The latest blooming cultivar was `Glauca'.

Acknowledge

We are grateful to Dr. Américo Hosnne for whole revision of the manuscript and to Mr. Luis Rosales for his assistance. We are indebted with Consejo de Investigación of the Universidad de Oriente, Venezuela for supporting this study identified as Project Nro. CI-3-0601-0705/95-97

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