Abstract: A field experiment was conducted at eastern block of Tamil Nadu Agricultural University, Coimbatore during summer (Feb-May) 2005 to investigate the influence of morphological modification through terminal clipping in selected varieties of sesame with Factorial Randomized Block Design (FRBD) with three replications employing two factors viz., varieties (SVPR 1, TMV 3 and TMV 4) and morphological modification by terminal clipping (at 15, 25, 35, 45 days after sowing and no clipping). The results of the study indicated that terminal clipping done at 35 DAS found to improve the crop architecture, yield attributes and yield of the sesame variety SVPR 1. The variety TMV 4 was also considered as an appropriate alternative in recording equal growth and yield parameters and yield for the same clipping practice.
INTRODUCTION
Sesame (Sesamum indicum L.) adorned as Queen of oilseeds is one of the most important ancient edible oilseed crops grown in India. Even though it is grown all over the world for its importance in food, medicine and industries, India has leading edge over its area (29.3%) and by 25% production (Duhoon et al., 2003). Among the oilseed crops, sesame ranks first for its higher oil content (46-64%) with 6335 kcal kg-1 of dietary energy in seeds (Kumar and Goel, 1994). The sesame has yield potential of around 2.0 t ha-1 but low in productivity (346 kg ha-1) and hence has tremendous options for management technologies. Yield is the manifestation of various physiological processes occurring in plants and they are usually modified by management practices in an environment. Besides, clipping of terminal leaves which activates the dormant lateral buds to produce more branches is an important operation for increasing sesame yield (Ramanathan and Chandrashekharan, 1998). Since management factors exert a profound effect on various growth and yield contributing characters in a given environmental condition, the present experiment was carried out to study the influence of morphological modification through terminal clipping in selected varieties of sesame.
MATERIALS AND METHODS
A field experiment was conducted during summer season (February-May)
of 2005 at Eastern block of Tamil Nadu Agricultural University, Coimbatore,
India. The farm situated in Western agro-climatic zone of Tamil Nadu at 11°
N latitude and 77° E longitude at an altitude of 426.7 m above mean sea
level. The initial soil analyses show that the soil was sandy clay loam in texture.
The soil is optimum in bulk density (1.33 mg m-3) and particle density
(2.66 mg m-3) with the porosity of 50%. The soil reaction was alkaline
(pH: 8.10) and the Electrical Conductivity is low (0.43 dS m-1).
The soil was low in available nitrogen (KMnO4-N: 237 kg ha-1),
medium in available phosphorous (Olsen-P: 14.4 kg ha-1) and high
potassium (NH4OAc-K: 395 kg ha-1). The experiment was
conducted out in Factorial Randomized Block Design (FRBD) with three replications
employing two factors {Factor I: varieties viz., SVPR 1, TMV 3 and TMV 4; Factor
II: manual terminal clipping done at 15, 25, 35 and 45 Days after Sowing (DAS)
and no clipping}. The crop was supplemented with nitrogen through urea, phosphorus
through single super phosphate and potassium through muriate of potash as basal
at the rate of 35: 23: 23 kg ha -1, respectively. Thinning and gap
filling were done on 15 and 25 DAS to achieve the required population. Five
sample plants of sesame from each treatment plot were selected at random and
labeled for biometric observations. The plant height, number of branches and
number of capsule per plant were recorded at harvest stage. The leaf area was
measured by using leaf area meter LICOR-2000 and Leaf Area Index (LAI) was calculated
using the formula
The Dry Matter Production (DMP) was recorded by shade drying the plant samples in air for one hour and then oven dried at 65±5°C till the constant weight was attained and DMP was expressed in kg per hectare. The crop was harvested separately from the plots when the leaves and stems were turned yellow and processed and the seed yield was recorded.
RESULTS AND DISCUSSION
Growth and Yield Characters of Varieties
The data of growth parameters such as branches per plant, Leaf Area Index
(LAI), DMP except plant height and yield attributes such as number of capsules
per plant and seed yield were superior in the variety SVPR 1 and
TMV 4 was found to be remained on par with SVPR 1 (Table 1).
The plant height values remind higher for TMV 4 compared with other two varieties.
Increased LAI was mainly due to enhanced number of leaves and large sized leaf
in SVPR 1 variety.
| Table 1: | Influence of clipping management (C) on growth and yield sesame varieties (V) |
Similar results are reported by Sarkar and Pal (2005). SVPR 1 recorded higher number of capsules per plant (101.1) and this was comparable with TMV 4. The total DMP of the crop mostly depends on leaf area, photosynthetic rate and dry matter partition. The positive increase in number of branches per plant (more than 15% over TMV 3 and 7% over TMV 4) might have offered higher chance for the increased production of leaves per plant and LAI, which subsequently resulted in higher DMP of SVPR 1 (more than 28% over TMV 3 for crop period). The results of Rao et al. (1990) lend support to this finding. SVPR 1 recorded maximum seed yield of 1010 kg ha-1 and was found to on par with TMV 4. This was due to more number of branches per plant that helped in production of more number of matured or productive capsules. Similar results are given by Kathiresan et al. (1997).
Growth and Yield Characters Influenced by Terminal Clipping Practices
In terminal clipping practice, the maximum plant height was noticed in without
clipping treatment when compared to all manual terminal clipping treatments.
Terminal clipping done at 35 DAS recorded more number of branches per plant,
DMP and LAI, except variation noticed in 30 DAS. In plants, the development
of auxillary buds are inhibited normally by Indole Acetic Acid (IAA) produced
in the apical meristem. If the source of auxin is removed by excising the apical
meristem, the lateral branching gets accelerated. Moreover, under terminal clipping,
the utilization of photosynthates by the crop for the production of lateral
branches would be higher and this might be the reason for increased number of
branches per plant at 35 DAS (23.6) over 45 DAS (17.6). Imayavaramban et
al. (2004) reported more number of branches with manual clipping of leaves,
leaving two pair of leaves above cotyledonary leaf. The increased number of
branches and production of more leaves which alter the crop canopy that in turn
increased the value of LAI. The terminal clipping practice at 35 DAS recorded
more number of capsules per plant (105.5). The clipping practice might have
efficiently altered the crop architecture, which in turn increased the lateral
branches that led to greater chance for development of source and sink features
in sesame. The beneficial impact of terminal clipping on yield attributes was
reported by Imayavaramban (2000). Clipping at 35 DAS recorded maximum seed yield
of 1125 kg ha-1. This was due to induction of more number of lateral
branches per plant.
Growth and Yield Characters of Varieties and Clipping Practices
The variety TMV 4 in combination with no clipping recorded maximum value
of 108.8 cm in producing taller plants than all other treatment combinations.
The maximum height by this treatment combination might be due to continuous
supply of auxin to apical meristematic tissues. This is in accordance with findings
of Venkadachalam (2003). In terms of production of branches per plant, all the
varieties clipped at 35 DAS produced higher number of branches owing to the
practice of terminal clipping which might have induced the formation of equally
dominant branches. This is in accordance with the result of Tewolde et al.
(1994). As known that for individual effect the rest of the growth parameters
was favourably influenced by the combination of variety SVPR 1 for 35 DAS clipping
owing to the positive response of the variety for the clipping practice. Sesame
variety SVPR1 when clipped at 35 DAS registered the highest seed yield of 1185
kg ha-1. The increase in seed yield of sesame in clipped plants over
non clipped plants was due to increase in more number of branches per plant
and capsules per plant. Similar results were reported by Venkadachalam (2003).
CONCLUSION
Among the varieties studied SVPR 1 showed its superiority in all the growth and yield characters namely number of branches per plant, LAI, DMP, number of capsules per plant and seed yield. In view of terminal clipping practice done at different crop growth stages, clipping at 35 Days After Sowing (DAS) recorded higher values over no clipping for all the growth parameters and yield attributes evaluated. Both SVPR 1 and TMV 4 were found to be highly amenable for clipping at 35 Days after Sowing (DAS) over rest of the combinations studied in improving growth characters, yield attributes and finally yield.