Resource conservation and performance of aonla (Emblica officinalis Gaertn) under varying tree density and in situ live mulching in rainfed conditions of north west India

Abstract

A study comprising of two densities of aonla (D : 6x6m and D : 8x8m) and four in- _{1 2} situ live mulching options (T : Control; T : cowpea mulch; T : weed mulch and T : _{1 2 3 4} sunhemp mulch) was conducted in split plot design with three replications for eight  years (2002 to 2009) at Selakui, Dehradun. Influence of different tree density and  residue input to soil due to different live mulch options on vegetative growth and  fruit yield and quality of aonla as well as soil and in-situ rain water conservation  was evaluated in aonla based agri-horti system with rainfed maize-wheat/mustard sequence on 2.0% sloping land provided with multi-slot devisors. D (277 trees ha-1) significantly enhanced tree height (15.0%), fruit yield (37.7%) and litter fall (47.8%) besides 47.0% reduction in soil loss over D (156 treesha ). D also significantly _{2 2} improved crown spread, girth at breast height (GBH), fruit weight and TSS: acid  ratio than D by 13.2, 9.0, 15.0 and 5.0%, respectively which may be attributed due to lower tree-tree interface on account of more space plant that directly relates to  higher availability and utilization of growth resources mainly the moisture and  nutrients. Different residue inputs to soil (variable in C:N ratio and quantity) under  distinct live mulch options invariably improved aonla tree growth, fruit yield and  quality over the control. T treatment outperformed other live mulch options and ₄  recorded maximum improvement in tree height, crown spread, GBH, fruit yield and litter yield that was equivalent to 16, 13, 9.0, 27 and 40%, respectively over  unmulched control. Among interactions (DxT), D T recorded significantly higher _{1 4} ^{2 -1 -1} tree height (3.54 m), crown spread (689.73 m ha ), fruit yield (8.14 t ha ), litter yield (3.27 t ha-1) and moisture conservation (57.65%) but variations in tree height  were statistically at par with D T (3.36 m). Similarly, D T also recorded _{1 3 2 4} ^{2 -1} significantly higher crown spread (2.78 m tree ), GBH (29.3 cm), fruit yield (35.63 kg ha ), litter yield (14.74 kg tree ) and fruit weight (42.2 g) but variations  ^{2 -1} were statistically at par with D T in crown spread (2.69 m tree ) and with D T in _{1 2 2 3} ^-1 litter yield (13.21 kg tree ). Significantly higher TSS: Acid ratio was produced by D T (5.35). D T recorded minimum soil loss (4.90 t ha ) and runoff (17.50%) and led to significantly higher moisture conservation (57.45%). The higher BC ratio (1.49) was observed in case of D₁T₄ followed by D₁T₂  with a netre turn of`194935 and ^-1 164425ha was produced due to fruits and dry wood biomass.