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The combined effect of two rapid multiplication techniques (sprout and top-shoot cutting) was assessed using four Dutch potato cultivars during 1991/92–1993/1994 at the Tuber Crops Research Centre (TCRC), Bangladesh Agricultural Research Institute (BARI), Gazipur-1701, Bangladesh. On average, a 70–80 g tuber produced 29 sprout cuttings which were subsequently used for taking top-shoot cuttings. Top-shoot cuttings were taken at a number of dates from 25 November and continued at 10 day intervals, thereafter, until 15 January. The number of top-shoot cuttings produced by 29 sprout cutting-derived plants varied (P<0·01) from 761 to 663 across the cultivars. Cardinal gave the greatest yield. Most of the characters studied varied (P<0·01) between cultivars but not over years while the interaction between cultivars and years was significant (P<0·01).Early planted top-shoot cuttings produced more tubers per plant (4·0) with a greater mean tuber weight (>22 g) than from the late planting (1 tuber and 5·5 g). On average, about 2·8 tubers per plant were produced with a mean tuber weight of 15·8 g. Cardinal and Patrones produced the most tubers per plant (2·9) and Diamant the greatest mean tuber weight (16·8 g). Cardinal gave the greatest yield (P<0·01) of tubers (268) followed by Patrones (241). The 29 sprout cutting plants derived from a 70±5 g tuber produced 160 tubers while the 771 top-shoot plants derived from 29 sprout cutting-derived plants produced 1420 tubers. The rate of multiplication of the combined two RM techniques was 1580[ratio ]1 against 11[ratio ]1 for the conventional method.

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Two separate experiments were conducted to evaluate the success of the establishment and growth of micro-cuttings of potato (5 -6 cm tall) in sand trays [38 cm (L) × 28 cm (W) × 7.5 cm (H) plastic trays] under controlled environment (22˚C ± 2˚C, 60 -75 μmosm -1 ·s -1 light energy for 16 h daily). In the first experiment, micro-cuttings of potato cv. Diamant were planted at six populations (500, 600, 700, 800, 900 and 1000 cuttings per tray) in treated sand (sun dry, 1% formaldehyde, 0.2% Dithane M-45 and control). The mortality percentage of micro-cuttings was nil for sun dry sand while formaldehyde and dithane M-45 treated sand had 1% -4% against 15% in the control with the highest population density. Mortality of micro-cuttings in formaldehyde and dithane M-45 treated sand trays were found not to be related to pathogenic organism rather toxic effect of these two chemicals. Micro-cuttings in Sun dry and control treatments showed better growth performance than these in chemically treated sand trays. In the second experiment, urea @ 1, 2 and 3 g per tray was applied as solid form after 15 days of planting the micro-cuttings and as liquid form @ 0.5, 1 and 2% solution sprayed in the micro-cuttings repeatedly after 15, 30, 45 and 60 days of planting. The micro-cuttings which received urea as solid state died within 2 -3 days and 2% urea solution was also detrimental. Urea solution @ 0.5% found to be very effective for vegetative growth of micro-cuttings in sand trays. The control was also good for vegetative growth but at a slower rate.

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