Abstract
Six field experiments were conducted at the Bangladesh Sugarcrop Research Institute (BSRI) Farm, Ishurdi for three consecutive years from November 2012 to December 2015 to evaluate the yield of tropical sugarbeet varieties as influenced by spacing, fertilization, date of sowing and intercropping with sugarcane. The experiment 1 was conducted with six varieties viz. CS 0327, CS 0328, HI 0044, HI 0473, Shubhra and Cauvery. The results revealed that Cauvery was the best variety in Bangladesh having the highest beet yield (75.46 t ha⁻¹) and sugar yield (11.82 t ha⁻¹) followed by CS 0328 (72.07 t ha⁻¹ and 11.17 t ha⁻¹, respectively). The experiment 2 was conducted with nine spacings viz. 50x20, 60x20, 70x20, 50x25, 60x25, 70x25, 50x30, 60x30 and 70x30 cm using the best variety (Cauvery). The spacing of 50x20 cm produced both the maximum beet yield (76.73 t ha⁻¹) and sugar yield (11.99 t ha⁻¹). The experiment 3 included nine fertilizer doses viz. T₁ (No fertilizer), T₂ (Only Cowdung 10 t ha⁻¹), T₃ (Urea, TSP and MoP @ 260, 100 and 225 kg ha⁻¹, respectively), T₄ (T₃ + Cowdung 5 t ha⁻¹), T₅ (T₃ + Cowdung 10 t ha⁻¹), T₆ (50% of T₃ + Cowdung 5 t ha⁻¹), T₇ (50% of T₃ + Cowdung 10 t ha⁻¹), T₈ (75% of T₃ + Cowdung 5 t ha⁻¹) and T₉ (75% of T₃ + Cowdung 10 t ha⁻¹) with variety Cauvery. It was observed that application of Urea, TSP and MoP @ 260, 100 and 225 kg ha⁻¹, respectively + cowdung 10 t ha⁻¹ produced the highest beet yield (90.49 t ha⁻¹) and sugar yield (13.65 t ha⁻¹). The experiment 4 was designed with the best and the second best varieties (Cauvery and CS 0328), best two spacings (50x20 cm and 60x20 cm) and four dates of sowing (30 October, 10 November, 20 November and 30 November). Cauvery with the spacing of 50x20 cm sown on 30 October produced the highest beet and sugar yields (87.81 t ha⁻¹ and 13.44 t ha⁻¹, respectively). The experiment 5 was conducted with two spacings viz. 50x20 cm and 60x20 cm and four fertilizer doses viz. Urea, TSP and MoP @ 260, 100 and 225 kg ha⁻¹, respectively; Urea, TSP, MoP and Cowdung @ 260, 100, 225 kg and 5 t ha⁻¹, respectively and Urea, TSP, MoP and Cowdung @ 195, 75, 169 kg and 10 t ha⁻¹, respectively with two and three splits of Urea and MoP. The spacing of 50x20 cm with fertilizer level of Urea, TSP, MoP and Cowdung @ 260, 100, 225 kg and 10 t ha⁻¹, respectively with 3 splits produced the highest beet and sugar yields (88.97 t ha⁻¹ and 13.37 t ha⁻¹, respectively). The experiment 6 was performed with eleven intercropping treatments viz. sole paired row cane (PRC) in conventional, sole PRC in spaced transplanting (STP), sole sugarbeet, PRC STP 45-day old settlings + 3 line sugarbeet (SB), PRC STP 60-day old settlings + 3 line SB, PRC STP 75-day old settlings + 3 line SB, PRC STP 45-day old settlings + 2 line SB, PRC STP 60-day old settlings + 2 line SB, PRC STP 75-day old settlings + 2 line SB, PRC in conventional + 3 line SB and PRC in conventional + 3 line SB during 2013-14 and 2014-15 cropping years were included to identify the best combination for intercropping system. The highest adjusted cane yield (157.78 t ha⁻¹), gross income (Tk. 4,33,895 ha⁻¹), net return (Tk. 3,14,895), benefit cost ratio (BCR) (2.65) and land equivalent ratio (LER) (1.64) were noted in PRC conventional + 3 line SB treatment. It can be concluded from the results of the study that as a sole crop, sugarbeet variety Cauvery may be cultivated with a spacing of 50x20 cm sown on 30 October with the fertilizer dose of Urea, TSP, MoP and Cowdung @ 260, 100, 225 kg and 10 t ha⁻¹, respectively with 3 splits of Urea and MoP for having maximum beet and sugar yields. Sugarbeet can also be intercropped with sugarcane under the method of PRC conventional plus 3 line sugarbeet (with the spacing of 50x20 cm) for obtaining the highest benefit.