MSc.

The investigation entitled, ―Rhizosphere management for higher root
production in ashwagandha (Withania somnifera L. Dunal)‖ was carried out at the
Instructional farm attached to the College of Agriculture, Padannakkad during
2015-17 to study the effect of integrated nutrient management practices and
summer irrigation on growth promotion and root production in ashwagandha.
The experiment was laid out in RBD with 14 treatments replicated twice.
The treatments were T1 - HDP in trenches mulched with polythene and filled with
enriched growing medium, T2 - T1 + Recommended dose of NPK, T3 - T1 +
Liquid organic manures, T4 - T2 + azospirillum, T5 - T3 + azospirillum, T6 - T4 +
B and Mg, T7 - T5 + B and Mg, T8 - T6 + Summer irrigation at 15 mm CPE, T9 -
T7 + Summer irrigation at 15 mm CPE, T10 - T6 + Summer irrigation at 30 mm
CPE, T11 - T7 + Summer irrigation at 30 mm CPE, T12 - HDP in trenches filled
with enriched growing medium, T13 - NRP in trenches filled with enriched
growing medium, T14 - Broadcasting in trenches filled with enriched growing
medium. The results of the field experiment revealed that all growth parameters of
ashwagandha were significantly influenced by treatment effects. In general, the
treatment T6 was found superior in enhancing vegetative growth. However, the
treatments did not exert any significant effect on primary, secondary and tertiary
branches at any of the growth stages.
The treatments had no significant effect on primary root number during
early stages of growth (45 DAT and 60 DAT). The effect of treatments was
evident from 75 DAT onwards. T10 at 75 DAT; T9 at 90 DAT; and T8 at 105 DAT
and 120 DAT recorded higher primary root number.
With respect to root characters, T8 recorded higher root number, T8 and
T10 recorded the greatest root length, T11 the highest root spread, and T10 the
highest root volume at the time of harvest. The treatment T10, recorded the highest
fresh and dry root weight per plant and fresh and dry root production per hectare.
The highest LAI and seed yield per plant and seed production per hectare were
registered by T6.
In general, relative leaf water content and leaf temperature were
unaffected by treatment effects. Crude alkaloid content ranged from 6.5 % to 10.4
%. The highest crude alkaloid content of 10.54 % was registered by T7. Other
biochemical parameters namely total sugar and total amino acid content were not
at all influenced by treatment effects. Azospirillum population ranged from 11.5 x
105 to 64 x 105 per gram dry soil. The highest population of 64 x 105 per gram dry
soil was registered by the treatments T8 and T5.
Seasonal consumptive use and mean daily consumptive use ranged from
145.73 mm to 250.80 mm and 1.22 to 2.09 mm respectively and T14 registered the
higher values. The highest crop water use efficiency of 474.78 g m-3 was recorded
by T10. Field water use efficiency varied from 84.46 to 222.31 g m-3 and the
highest value was recorded by T6. The treatment which recorded the highest value
of field water use efficiency also registered the highest water productivity of
1313.47 g m-3.
The highest nitrogen content was recorded by T6. T8, T9 and T10 registered
higher contents of phosphorus, potassium and boron respectively.
The treatment, T10 was found worthwhile for popularization with respect to
higher fresh and dry root yield per plant and root production per hectare, dry
matter production, crop water use efficiency, gross income, net income and BCR.