STUDY ON LEAF QUALITY OF MULBERRY (MORUS ALBA L) VAR. S-1635 THROUGH REARING AND REELING OBTAINED FROM DIFFERENT PLANTING GEOMETRY AND INTERCROPPING

An experiment was conducted during 2009-2010 at the Central Sericultural Research and Training Institute, Berhampore (West Bengal) on bioassay with two multi x multi [N (M) x M 12W)] hybrid rearing in unfavourable season (July and September) and two multi x bi (N x NB4D2) hybrid rearing in favourable season (November and February) as well as reeling study to assess the quality of leaf of high yielding and popular mulberry variety S-1635, obtained through seven various planting geometry (spacing) in respect of variable number of plants (ranged from 12245 —27778 nos./ha) and one suitable intercropping in each of the four seasons followed by incorporation of biomass of two used leguminous (green gram and cowpea) intercrops in soil along with one green manure (sunnhemp) crop in July-September under five crop schedule per year cultivated under irrigated, Gangetic alluvial soil conditions.

It was already ob'served from earlier study (paper communicated) that the quality of leaf was improved in all the five paired row system of plantation including 90cm x 90cm spacing compared to 60cm x 60cm i.e. present recommended spacing. With regard to leaf yield, T6 [(90cm + 120cm) x 60cm spacing] performed overall promising and economic due to improvement in soil nutrient status, growth attributing characters, almost similar and sustainable leaf yield and maximum leaf yield / plant in presence of 15873 plants/ha in T6 compared to 27777 plants/ha in 60cm x 60cm spacing, better leaf quality, optimum intercrop yield and net profit over control (60cm x 60cm).

The leaves obtained from above seven treatments were fed to silkworm (Bombyx more L.) in four different seasons. The average result of two (July and September) rearing with multi x multi [N (M) x Ml2W)] silkworm hybrid under unfavourable season revealed that the effect of the treatments were found at par on the economic parameters of rearing and reeling and the overall performance in respect of rearing and reeling in T4 and T6 were also found similar or better in some of the parameters over other treatments as well as control (60cm x 60cm).

In case of favourable season, the average result of two (November and February) rearing with multi x bi (N x NB4D2) silkworm hybrid indicated that the effect of the treatments were also found at par on the economic parameters of rearing and reeling except SR% and filament length (FL) which were found significant. The second best performances were observed in T6 in respect of wt. of 10 matured larvae, SR (%) and renditta and T4 performed best in respect of NBFL.

It was thus concluded from the study that the paired row system of plantation especially [(90cm + 120cm) x 60cm spacing] i.e. T6 performed overall better both in respect of leaf yield, leaf yield/plant, leaf quality, intercrop yield, net profit, economic as well as better performances on important characters of rearing and reeling compared to earlier recommended spacing (60cm x 60cm) for mulberry cultivation under irrigated condition. Hence, this paired row spacing [(90cm + 120cm) x 60cm] may be recommended to the farmers for mass scale adoption because of better leaf yield and intercrop yield, leaf yield/plant, leaf quality, rearing and reeling performances, soil health and net profit along with the mechanization facility.