Feng-Rui Li

Incorporation of ridge and furrow method of rainfall harvesting with mulching for crop production under semiarid conditions

Abstract A plastic-covered ridge and furrow rainfall harvesting (PRFRH) system combined with mulches was designed to increase water availability to crops for improving and stabilizing agricultural production in the semiarid Loess region of northwest China. The system was built by shaping the soil surface with alternate ridges and furrows along the contour. The plastic-covered ridges served as a rainfall harvesting zone and furrows as a planting zone. Some materials were also used to mulch the furrows to increase the effectiveness of the harvested water. This system can make better utilization of light rain by harvesting rainwater through the plastic-covered ridge. The field experiment (using corn as an indicator crop) showed that grain yields in the PRFRH system with mulches in 1998 and 1999 were significantly higher than the controls, with an increase of 4010–5297xa0kg per ha (108–143%). In most treatments, the water use efficiencies (WUE) were in excess of 2.0xa0kgxa0m −3 . The WUE values of corn in this system were 1.9 times greater than the controls in 1998 and 1.4 times greater than the controls in 1999. The plastic-covered ridge led to a yield increase of 3430xa0kg per ha (92%) in 1998 and of 1126xa0kg per ha (21%) in 1999 compared with the uncovered ridge. On average, the additional mulches in the furrow brought about a yield increase of 8–25%. Based on the results of this study and other researches, this technique can increase corn grain yield by 60–95% in drought and average years, 70–90% in wet years, and 20–30% in very wet years. The PRFRH system had the potential to increase crop yield and produced greater economic benefit, therefore it could be used in regions dominated by light rainfall of low intensity where crops generally fail due to water stress.

Soil water availability alters the inter- and intra-cultivar competition of three spring wheat cultivars bred in different eras.

Competition for water generates a classic aspect of the tragedy of the commons, the ‘race for fish’, where crops must allocate more resource to acquisition of the limiting resource than is optimal for crop yield allocation. A pot experiment using a simple additive (target–neighbour) design was conducted to examine the above-ground and below-ground growth of three spring wheat (Triticum aestivum L.) cultivars when grown alone and in mixtures at three levels of water availability. The effects of competition and water availability were compared by observing patterns of growth, biomass allocation and below-ground outcomes. Competitive interactions were investigated among cultivars ‘HST’, ‘GY602’ and ‘LC8275’, target plant of each cultivar grown without neighbouring plants are referred to herein as control plant and one target plant of each cultivar sown surrounded either by same or another cultivar as intra- or inter-cultivar competition. Competitive ability was assessed as the response ratio (lnRR) between the target plant surrounded by six other plants and the target plant in isolation. Our results showed that the cultivar ‘HST’, released over a century ago, produced a higher biomass and grain yield than the more recently released cultivars ‘LC8275’ and ‘GY602’ when grown as isolated plants with sufficient water supply. However, competition for resources from neighbours led to target plant biomass and grain yield being significantly reduced relative to controls in all three cultivars, particularly in ‘HST’. When subjected to intra-cultivar competition, the two recently released cultivars ‘LC8275’ and ‘GY602’ had higher grain yields and water use efficiency for grain than ‘HST’ in all three water regimes. The landrace ‘HST’ had better and significantly linear relationships between biomass and biomass allocation, root length and specific root length, whereas the recent and modern cultivars had much more water-related species-specific changes in root morphology and allocation patterns. These results suggest that crop traits that influence competitive ability, such as biomass allocation to roots and root plasticity in response to drought have changed in modern wheat cultivars because of breeding and selection.

Ground-dwelling arthropod community response to native grassland conversion in a temperate desert of northwestern China

Oases are common in desert regions of northwestern China and are major sites for human settlement. The implementation of oasis conservation planning has led to afforestation with appropriate shrubs and trees in the native grasslands surrounding inhabited oases. However, little is known about how this Land use change from native grassland to shrub and tree plantations influences the composition of ground-dwelling arthropod communities and the performance of their different trophic groups. To address this, we measured activity density, taxon richness, and relative abundance of four different ground arthropod trophic groups (spiders, beetle predators, beetle herbivores, and beetle detritivores) and several environmental variables affecting arthropod distributions (vegetation cover, ground temperature, soil moisture, soil properties, and leaf litter) along an experimentally established land use change gradient of a mature shrub (Haloxylon ammodendron) planation, a mature poplar (Populus gansuensis) plantation and a mature pine (Pinus sylvestris) plantation, as well as a native grassland from which all cultivated systems were converted. We found that converted shrub plantation had much lower activity density of predatory, herbivorous, and detritivorous beetles; similar activity density of spiders; and similar taxa richness of all four trophic groups relative to the native grassland. However, converted forest plantations regardless of tree species had much higher activity density of spiders, lower activity density of the three beetle groups, much higher richness of predatory beetles, and lower richness of herbivorous and detritivorous beetles. We also found a change in the composition of the ground arthropod community that was largely driven by changes in ground temperature and leaf litter mass. We conclude that conversion of native grassland to shrub and tree plantations can significantly affect ground-dwelling arthropod communities, reducing the activity of ground-dwelling beetle assemblages while increasing that of ground-dwelling spider assemblages. These findings are important for conserving native arthropod diversity in desert ecosystems.

DROUGHT STRESS: Soil Water Availability Alters the Inter- and Intra-Cultivar Competition of Three Spring Wheat Cultivars Bred in Different Eras: Soil Moisture and Plant Competition Affect Wheat

Competition for water generates a classic aspect of the tragedy of the commons, the ‘race for fish’, where crops must allocate more resource to acquisition of the limiting resource than is optimal for crop yield allocation. A pot experiment using a simple additive (target–neighbour) design was conducted to examine the above-ground and below-ground growth of three spring wheat (Triticum aestivum L.) cultivars when grown alone and in mixtures at three levels of water availability. The effects of competition and water availability were compared by observing patterns of growth, biomass allocation and below-ground outcomes. Competitive interactions were investigated among cultivars ‘HST’, ‘GY602’ and ‘LC8275’, target plant of each cultivar grown without neighbouring plants are referred to herein as control plant and one target plant of each cultivar sown surrounded either by same or another cultivar as intra- or inter-cultivar competition. Competitive ability was assessed as the response ratio (lnRR) between the target plant surrounded by six other plants and the target plant in isolation. Our results showed that the cultivar ‘HST’, released over a century ago, produced a higher biomass and grain yield than the more recently released cultivars ‘LC8275’ and ‘GY602’ when grown as isolated plants with sufficient water supply. However, competition for resources from neighbours led to target plant biomass and grain yield being significantly reduced relative to controls in all three cultivars, particularly in ‘HST’. When subjected to intra-cultivar competition, the two recently released cultivars ‘LC8275’ and ‘GY602’ had higher grain yields and water use efficiency for grain than ‘HST’ in all three water regimes. The landrace ‘HST’ had better and significantly linear relationships between biomass and biomass allocation, root length and specific root length, whereas the recent and modern cultivars had much more water-related species-specific changes in root morphology and allocation patterns. These results suggest that crop traits that influence competitive ability, such as biomass allocation to roots and root plasticity in response to drought have changed in modern wheat cultivars because of breeding and selection.