The Effects of Water and Fertilizer Coupling on Plant and Soil Nitrogen Characteristics and Fruit Growth of Rabbiteye Blueberry Plants in a Semi-Arid Region in China

To evaluate the effects of nitrogen(N)and irrigation coupling on the soil N distribution,plant N utilization,and fruit yield of rabbiteye blueberries(Vaccinium virgatum),a field experiment was designed using two factors(water and fertilizer application)with four levels of irrigation and three levels of fertilization,and a control.Under the different water and fertilizer combinations,N primarily accumulated in the leaves.Irrigation and N application within appropriate ranges(pure N≤29 g/plant and irrigation volume≤2.5 L/plant)significantly improved the blueberry fruit yield.Increases in water and N within these ranges promoted the effective accumulation of N in various organs and the absorption and utilization of N in the plants,which ultimately promoted blueberry yield.With increased N application rate,the nitrate N content of the 0–20 cm and 20–50 cm soil layers increased.With increased irrigation volume,the nitrate N content of the 0–20 cm soil layer decreased,while the nitrate content in the 20–50 cm soil layer increased.Low N and moderate water treatments resulted in high fruit yields and reduced nitrate N retention in the soil.Under these conditions,the economic input-output ratio was high and the soil N accumulation was low,and thus the economic and ecological benefits were maximized.

Plant food sources and stone tools' function at the site of Shunshanji based on starch grain analysis

The upper-middle Huai River valley(HRV) is located in the transition zone in the middle of eastern China. Previous studies have shown that the past populations in the upper HRV obtained plant food through gathering and cultivation of both rice and millet during the middle Neolithic. However, for the middle HRV it is not very clear what methods were used by humans to obtain plant food in that time. In this paper, starch grain analysis was carried out on 17 stone tools and 29 cauldron pottery sherds unearthed at Shunshanji(8.5–7.0 kyr BP), which is known as the earliest Neolithic site in the middle HRV excavated so far. Here, ancient starches from Coix lacryma-jobi, Triticeae, Oryza sativa, Trichosanthes kirilowii and one unidentified specie were recovered. This study contributes to the limited knowledge of food strategies as observed in the middle HRV. It demonstrates that both gathering and cultivation of rice took place during the middle-Neolithic. Among the identified species, Coix lacryma-jobi appears to have been the main plant food at Shunshanji. Moreover, it is clear that Oryza sativa was not consumed as much as other plant species according to the occurrence frequency of different starch grains. Starch grains were also found on the used surfaces of grinding stone implements as well as pestles, which means that these stone tools were used for food processing. In addition, axes from Shunshanji may also have been used for food processing as well as wood working because starches were also found on the edge of axes. Information about subsistence strategies and tool use at Shunshanji will also be helpful to understanding the utilization of plants and agricultural development in the middle HRV during the early-middle Neolithic period.