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Bamboo-based agroforestry is a promising option for sustainable land management in India. Optimal management of bamboo-based mixed species production systems, however, requires an understanding of bamboo spacing, root activity and distribution of bamboo roots, and the soil nutrient capital of the site. We examined the performance of turmeric as an understorey crop in 7-year old bamboo (Dendrocalamus strictus (Roxb.) Nees) stands of varying spacing treatments (4 × 4, 6 × 6, 8 × 8, 10 × 10 and 12 × 12 m) at Kerala Agricultural University Campus, Thrissur, Kerala, India. In order to better understand turmeric and bamboo growth parameters, soil physico-chemical properties, understorey light availability and turmeric root activity by soil injection of ³²P were determined in mixed (turmeric + bamboo) and sole turmeric situations. To characterize root activity, ³²P was applied at 10 cm depth to the turmeric plants in raised beds established between the two central rows of bamboo in all experimental plots. Growth attributes of bamboo were recorded and the soil was analyzed for physico-chemical properties before intercropping. Results revealed that spacing treatments exerted profound influence on bamboo growth. For instance, clump height decreased by 19 % in the widest (12 × 12 m) bamboo spacing compared to that of the closest (4 × 4 m) spacing. However, widely spaced bamboo exhibited better clump diameter, crown coverage and turmeric rhizome yield, whereas, closest (4 × 4 m) spacing of bamboo plot recorded least rhizome yield of 8 Mg/ha; this was 58 % less compared to widest spacing of 12 × 12 m (19.32 Mg/ha). Soil N, P and K at widest spacing was 56, 45 and 33 % less compared to that of the closest spacing. NPK uptake by turmeric also increased in the wider spacing treatments. Factors contributing to reduction in growth of turmeric in the denser bamboo stands may be the high LAI (6.77 in 4 × 4 m spacing) as compared to widest spacing (0.44 in 12 × 12 m spacing) of bamboo, low understorey PAR (107 µmol/sec/m²) and high root competition. Due to competition by bamboo, 89 % decline in ³²P absorption by turmeric at closest spacing of bamboo was observed compared to the bamboo-less plot. On a final note, turmeric, although a shade tolerant Zingiberaceae crop, may perform better if light transmittance is between 66 and 86 % and for optimal performance of the understorey turmeric in mixed species systems, wider bamboo spacings beyond 8 × 8 m are recommended.
