Root distributions in tillage layers and yields of pumpkin and oil sunflower in an intercropping system

Abstract

Studies on the distribution of roots of pumpkin and oil sunflower in tillage layers and their relations with their above-ground biomass in an intercropping system were conducted by digging roots by layers, combined with DT-Scan and the WinRHIZO root analysis system, during harvest in the plateau of the northwest part of Hebei Province, China. The results of analyzing roots and ratio of root to shoot showed that oil sunflower had an advantage over pumpkin in the intercropping system. Root dry weight of oil sunflower in treatments of pumpkin intercropped with one row (J1) and two rows of oil sunflower (J2) was, respectively, 2.5 and 1.83 times that of sole oil sunflower cropping (YD); the root length was 1.25 and 1.27 times, the root surface area was 1.20 and 1.14 times, and the root volume was 1.53 and 1.44 times that of sole oil sunflower cropping, respectively. As oil sunflower was dominant in absorbing nutrition and water in the intercropping system, the growth and development of pumpkin were restricted. Root dry weight of pumpkin in sole cropping (ND) was 1.5 and 1.9 times as much as that in treatments of J1 and J2 in a 0- to 40-cm soil layer, with the root length, surface area, and volume being 1.02 and 1.13, 1.04 and 1.26, 1.22 and 1.22 times that of treatments of J1 and J2, respectively. The root and the above-ground biomass of intercropped pumpkin with oil sunflower were lower than those in sole pumpkin cropping, while those of oil sunflower were the opposite. Root density of pumpkin decreased in power function with the soil layers, while it decreased by exponential function in oil sunflower. It was concluded that sole pumpkin cropping rather than pumpkin-oil sunflower intercropping is the suitable planting regimen in this area.