Effect of sowing time, seed rate and harvesting duration on yield of Ashwagandha (Withania somnifera)

Introduction

Ashwagandha is an important cash crop for greening the arid and dry zone having medicinal properties belonging to solanaceace. Ashwagandha is late sown kharif crop and harvested between 150-170days after sowing. It is mainly cultivated in the drier parts of Madhya Pradesh, Punjab, Rajasthan and South India. In Madhya Pradesh, it is cultivated in about 4000 hectares area 1 . Ashwagandha is an important drug used in ayurvedic medicines. The pharmacological activity of the roots is attributed to the presence of alkaloids withanine and somniferine. The roots also contain stach, reducing sugars and glycosides. The plant is a rich source of crude protein, calcium and phosphorous [1] . The leaf paste and decoction are used both externally and internally for many ailments like sore eyes, boils hand and foot swellings, wounds etc. An infusion of bark is used for control of asthma. The fruits and seeds are used in chest complaints. Ashwagandha is commercially grown for its roots. Now-a-days, use of ayurvedic medicines is increasing due to fewer side effects. The drug is mainly used in ayurvedic and unani preparations. The alkaloid withaferine-A which is present in roots having antibiotic and antitumour prorerties [2] . Plant extract of ashwagandha on stored pulses and products showed 100 per cent mortality of callosobruchus pest [3] . Crude leaf extract of ashwagandha gave 90-100 per cent inhibition of Tobacco Mosaic Virus in chillies [4] .

Materials and Methods

The experiment was carried out during August 2009-March 2010 in Herbal garden, Rajendranagar, Hyderabad. The experiment was laid out with two sowing dates (August 15 th and August 30 th ), three seed rates (10 kg/ha, 12 kg/ha and 14 kg/ha) and three harvesting durations (150 DAS, 180 DAS and 210 DAS) in Completely Randomized Block Design with factorial concept comprising a total of 18 treatments replicated thrice. The land was brought to fine tilth by ploughing and harrowing. The experimental area was divided into plots of 2m x 3m size. Irrigation channels of 0.5m size were provided. The cleaned seeds mixed with sand at the ratio of 1:1 and sown directly in the field by broadcasting method. Uniformly growing five plants were randomly selected and tagged from the net plot area in each treatment and replication for the purpose of recording the observations at harvest. The data recorded on yield were subjected to statistical analysis. The data were analyzed using computer software programmed by the method of variance [5] .

Results and Discussion. Effect of sowing time on yield:

The August 15 th crop performed better in yield characters compared to sowing on August 30 th . Yield characters like maximum length of the root (29.43 cm), thickness of the root (1.23 cm), fresh root yield (13.91 q/ha), dry root yield (3.38 q/ha) and total biomass production (1109.25 g/m 2 ) were recorded in August 15 th sowing. Minimum days taken for harvesting of seed (152.96 days) in August 15 th sown crop. The root yield of Ashwagandha was significantly influenced by dates of sowing. The results indicated that the crop sown on August 15 th recorded significantly higher root yield (3.38 q/ha) over the August 30 th sowing (2.26 q/ha). This clearly indicated that the optimum date of sowing for Ashwagandha crop would be August 15 th .Similar results at Rahuri (Maharashtra) were reported having significant effect of dates of sowing on root yield of Ashwagandha [6] . The higher root yield due to sowing on August 15 th could be attributed to better performance of crop with respect to yield contributing characters at harvest. The root length (29.43 cm), thickness of the root (1.23 cm), fresh root yield (13.91 q/ha) and dry root yield (3.38 q/ha) were significantly higher with the crop sown on August 15 th compared to August 30 th sowing. Similar studies of significant effect of date of sowing were reported on root length of Ashwagandha [7] . In the present study the crop sown on August 15 th recorded higher leaf area compared to August 30 th sowing. Higher total biomass production per plant with August 15 th sowing can be related to higher values of growth indices like leaf area. It is well established that infrastructure of the plant is decided by the growth indices. This concept not only involves the final crop yield and its components also probes into the physiological events that have occurred in early growth stages causing variation in the yield. The significant effect of dates of sowing on root yield were reported in Ashwagandha at Jobner (Rajasthan) [7] .

Effect of seed rate on yield

The seed rate of 10 kg/ha (S 1 ) recorded maximum length of the root (28.49cm), maximum dry root yield (2.88 q/ha), total biomass production (997.54 g/m 2 ) when compared to S 2 (12 kg/ha) and S 3 (14 kg/ha). Highest dry root yield with thick roots and good quality roots were reported with seed rate of 10 kg/ha on yield of Ashwagandha [8] . Similar results of good quality root yield were reported in Ashwagandha [9,10] .

Effect of harvesting duration on yield

The harvesting duration of 150 DAS (H 1 ) recorded maximum length of the root (28.46 cm) when compared to H 2 (180 DAS) and H 3 (210 DAS). Yield characters like fresh root yield (13.48 q/ha), dry root yield (3.12 q/ha), total biomass production (1079.39 g/m 2 ) recorded maximum in 210 days of harvesting duration compared to 150 days and 180 days. The root yield of Ashwagandha increased with increased period of harvesting. This indicated that the optimum stage of harvesting would be 180 DAS. Plant height and stem branches showed strong positive association with root yield and also showed positive direct effect. The positive contribution through indirect effect of other yield contributing components like root length, root thickness and seed yield showed positive association with root yield [11] . The results are in conformity who reported by a significant increase in yield of both thin and thick roots (92.0 to 171.0kg/ha and 25.9 to 43.6 kg/ha respectively) with the increase in days of harvesting of Ashwagandha from 90 to 210 [8] . The higher root yield of Ashwagandha crop harvested at 210 DAS can be attributed to higher values of yield parameters at harvest. The root length, root diameter, fresh root weight and dry root weight were significantly higher with the crop harvested at 210 DAS compared to other harvesting stages. The yield parameters of Ashwagandha increased with increased period of harvesting. The higher values of yield were mainly attributed to better growth of the plant, which can be related to higher values of growth parameters like plant height, primary branches etc.

Interactions

August 15 th sowing and 12 kg/ha seed rate (D 1 S 2 ) recorded significantly maximum thickness of the root (0.94cm) at 120 DAS. A combination of August 15 th sowing, 12 kg/ha seed rate and harvesting duration of 210DAS (D 1 S 2 H 3 ) recorded significantly maximum thickness of the root (1.32 cm) at 210 DAS. Though interaction treatments were not significant, a combination of August15 th sown crop with a seed rate of 12 kg/ha and harvesting duration of 210 DAS (D 1 S 2 H 3 ) recorded maximum length of the root (31.63 cm). Maximum fresh root yield (15.63 q/ha) and dry root yield (4.40 q/ha) were recorded with August15 th sown crop with a seed rate of 12 kg/ha and harvesting duration of 210 DAS (D 1 S 2 H 3 ). Though interaction treatments were not significant, a combination of August15 th sown crop with a seed rate of 12 kg/ha and harvesting duration of 180 DAS (D 1 S 2 H 2 ) recorded early harvesting of seed (150.00 days) and highest total biomass production (1304.18 g/plant).

References

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