The experiment was conducted at Regional Agricultural Research Station, Hathazari, Chittagong, Bangladesh during Rabi season of 2016–17. The experiment site was located in between 22°50´N latitude and 91°79´E longitude. It was situated in the Chittagong coastal plain i.e. agro ecological zone no. of 23. Soil texture of the experiment field was Clay loam to sandy loam and soil PH was 6.3. The maximum temperature range was 23– 25oC and the minimum temperature range was 10–15oC. No major rainfall occurred during the experiment period. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. The unit plot size was 5m × 4m. Seven treatment combinations were used in this experiment viz. T1= sole maize, T2= 1 row maize (100%) + 1 row squash (6 plants/row), T3= maize paired row (100%) + 1 row squash (5 plants/row), T4= maize paired row (100%) + 1 row squash (4 plants/row), T5= maize paired row (100%) + 2 row squash (5 plants/row), T6= maize paired row (100%) + 2 row squash (4 plants/row), T7= sole squash. The spacing of Sole maize and maize normal plating was (75 cm × 25 cm) whereas in maize paired row planting, spacing was row to row distance 37.5 cm and plant to plant distance was 25 cm (BARI, 2014). Among the treatments there was no difference in total plant populations/area of maize. Sole squash spacing was 100 cm × 80 cm. Squash var. Hybrid Bulam House and maize var. BARI Hybrid maize–9 were used in the experiment. On 15th November, 2016 maize seeds were sown and 15 days old squash seedlings were transplanted according to the treatments. Fertilizers were applied @ N100P40K80S10Zn5B1.2 kg/ha; @ N260P72K148S48Zn4B2 kg/ha and @ N300P73K150S50 Zn6B2 kg/ha for sole squash, sole hybrid maize and intercropping respectively (BARC, 2015). The sources of N, P, K, S, Zn and B were urea, triple super phosphate (TSP), muriate of potash (MoP), gypsum, zinc sulphate and boric acid, respectively. All fertilizers except N were applied at the time of final land preparation. Nitrogen was side dressed in three equal splits at 10, 30 and 50 days after planting followed by light irrigation. Fungicide (Dithane M 45) @ 1 ml/liter water was sprayed at every 10–day interval beginning from 25 days after planting to 70 days after planting for preventing fungal disease. Pheromone traps (Cue lure) were used to control cucurbit fruit fly in the squash field @ 10 traps/ha from 30 days after planting up to harvesting of squash (Cork et al., 2003). Squash was harvested upon maturity from the last week of January to 2nd week of February, 2017 and maize was harvested at 3rd week of April, 2017 upon maturity. Data on yield contributing parameters of maize such as plant height (cm), no. of cobs/plant, cob length (cm), weight of 1000 grain (g) and seed yield/plot (kg) were recorded. Data on yield contributing parameters of squash such as no. of fruits/plant, average fruit weight (g), weight of fruits/plant (kg), and fruit yield/plot (kg) were also recorded. All the data were statistically analyzed using R–package. Plot yields were converted to crops yield in t/ha. Component crop (squash) yields were converted to maize equivalent yield using the following formula: MEY = Ym+ {(Ys× Ps) /Pm}. Here, MEY = maize equivalent yield, Ym= yield of maize; Ys= yield of squash; Ps= selling price of squash; Pm= selling price of maize (Thayamini et. al., 2010 and Uddin et. al., 2009).
The land equivalent ratio (LER) was calculated using the following formula: LER = (YiC1/YsC1) + (YiC2 / YsC2)
Here, YiC1=intercropping yield of crop1; YsC1=sole cropping yield of crop1; YiC2=intercropping yield of crop2; YsC2=sole cropping yield of crop2 (Begum et al., 2016, Uddin et. al., 2009 and Metwally et. al., 2015).
When LER value is higher than 1 it means there is an advantage of intercropping in terms of the use of resources for the plant growth compared to sole cropping. When LER value is lower than 1 it means that sole cropping use the resources more efficiently in comparison with intercropping (Sullivan, 1998). Cost of production, gross returns and net returns were calculated. Benefit cost ratio (BCR) was calculated by the formula of, BCR = Gross Return/ Cost of production (Esmat et al., 2011).