Effect of plant spacing and organic mulch on growth,yield and quality of natural sweetener plant Stevia and soil fertility in western Himalayas

Document Type: Research Paper

Authors

1 Natural Plant Products Division, CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific and Industrial Research), Post Box No 6, Palampur 176 061 (HP), India.

2 Hill Area Tea Science Division, CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific and Industrial Research), Post Box No 6, Palampur 176 061 (HP), India.

3 Biodiversity Division, CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific and Industrial Research), Post Box No 6, Palampur 176 061 (HP), India.

Abstract

The use of leaf mulch as a soil cover is effective in improving yield and soil
fertility. The field experiment was conducted during 2010 and 2011 to study the
effect of plant spacing (30 cm × 30 cm and 45 cm × 30 cm) and four mulches {pine
needles (Pinus roxburghii), poplar leaf (Populus deltoides), silver oak (Grevillea
robusta) tree leaf mulch and unmulched control} on growth, yield, quality of stevia
and soil fertility. Weed count and dry weed weight was not affected by spacing
levels during August and at the time of harvest, whereas, in unmulched plots it was
significantly higher than mulched plots. Dry leaf yield, total dry biomass and leaf
area index (LAI) were significantly higher in 30 cm × 30 cm spacing level and
poplar leaf mulch. All the mulched plots significantly increased organic carbon
(OC), available nitrogen (N), phosphorus (P) and potassium (K), bacterial and
fungal population compared to unmulched plots. Rebaudioside-A content was
higher in plots mulched with poplar leaves. Steviol glycosides were not
significantly affected by different treatments. Soil biological activities were also
enhanced by tree leaf mulches. Leaf mulch enhanced microbial biomass, relative to
non-mulched soils, likely via improving C and water availability for soil microbes.
Keywords: Stevia; Organic mulch; Spacing; Growth; Yield; Steviol glycoside.