Microclimate modification and response of wheat planted under trees in a fan design in northern India
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The presence of trees in fields may help overcome the physiological stress that happens to late sown wheat (Triticum aestivum L.) in subtropical India. Wheat was planted in an agroforestry system with Eucalyptus tereticornis trees on 7 January 1998 in a fan design that provided different combinations of tree row spacing and orientations. Crop profile microclimatic conditions and the resulting growth responses of the intercropped wheat were studied to explore the potential of agroforestry systems to influence late sown wheat yields under different tree row spacing and orientations. Agroforestry treatments exhibited a potential to optimize the microclimatic conditions for seedling emergence, tillering and earhead emergence at some tree row orientations and distances from the crop. The net radiation distribution at three stages of crop growth indicated that the radiation availability was lower in all the agroforestry treatments than for the sole crop. The tree row orientation and distance influence the growth behavior of the crop but the effect of sun angle (which changes with season) can change their influence over time. The deterioration or amelioration of microclimatic conditions in agroforestry with the passage of time should be expected because of altered interaction patterns between sunrays and tree canopy resulting from changing solar elevation and angle of sunrays. Statistically similar harvest indices in all the treatments despite lower total biological yields in agroforestry treatments revealed that microclimatic conditions under agroforestry were more favorable for wheat growth attributed to reduction in heat load during the post anthesis period.
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