To capture more nutrients, root systems of maize ( Zea mays L.) and soybean ( Glycine max L.) exhibit morphological and physiological plasticity to a localized supply of phosphorus (P). However, the mechanisms of the interaction between light intensity and P affecting root morphological and physiological alterations remain unclear. In the present study, the regulation of P uptake capacity of maize and soybean by light intensity and localized P supply was investigated in a low solar radiation area. The plants were grown under continual and disrupted light conditions with homogeneous and heterogeneous P supply. Light capture of maize and soybean increased under the disrupted light condition. Plant dry weight and P uptake were increased by more light capture, particularly when plants were grown in soil with heterogeneous P supply. Similarly, both localized P supply and disrupted light treatment increased the production of fine roots and specific root length in maize. Both homogeneous P supply and disrupted light treatment increased the malate and citrate exudation in the root of soybean. Across all of the experimental treatments, high root morphological plasticity of maize and root physiological plasticity of soybean were associated with lower P concentrations in leaves and greater sucrose concentrations in roots. It is suggested that the carbon (C), exceeded shoot growth capabilities and was transferred to roots as sucrose, which may serve as both a nutritional signal and a C-substrate for root morphological and physiological changes.

Modern agriculture is facing new challenges in which ecological and molecular approaches are being integrated to achieve higher crop yields while minimizing negative impacts on the environment. The application of biofertilizers could meet this requirement. Biofertilizer is a natural organic fertilizer that helps to provide all the nutrients required by the plants and helps to increase the quality of the soil with a natural microorganism environment. This paper reviewed the types of biofertilizers, the biological basic of biofertilizers in plant growth promotion. This paper also assayed the bidirectional information exchange between plant-microbes in rhizoshpere and the signal pathway of plant growthpromoting rhizobacteria (PGPR) and plant growth-promoting fungi (PGPF) in the course of plant infection. At last, the challenges of the application and the promising future of biofertilizers were also discussed.

Siberian wildrye (Elymus sibiricus L.) is a globally important cool‐season forage grass for semiarid regions. However, its seed yield is often low or inconsistent. As previous studies examined the effects of row spacing and P and N levels on seed production of Siberian wildrye separately, this study was focused on the combined effects of four row spacings (30, 45, 60, 75 cm), four P application levels (0, 60, 90, 120 kg P ha−1), and four N application levels (0, 30, 60, 90 kg N ha−1). Treatments were established within a split‐split‐plot factorial arrangement, with main plots arranged in a randomized complete block design with four replicates. The field experiment was conducted on a Lithic Haprendoll soil type at the Guyuan farm in Hebei Province, China, during the 2010, 2011, and 2012 growing seasons with no supplemental irrigation. Narrow row spacing improved seed yield by increasing fertile tillers m−2, with 30 cm being the optimal row spacing. Phosphorus application increased seed yield by increasing spikelets per fertile tiller, with 90 kg P ha−1 being the optimal P application level. Nitrogen application had no significant influence on seed yield in any year. Path analysis structural equation modeling revealed that spikelets per fertile tiller and fertile tillers m−2 had significant and direct path coefficients with variances in seed yield. The best management practices for optimal seed yield of Siberian wildrye was 30‐cm row spacing, 90 kg P ha−1, and no additional N beyond 109 g kg−1 available soil N under rain‐fed conditions with annual rainfall <300 mm.

Water shortage has threatened sustainable development of agriculture globally as well as in the North China Plain (NCP). Irrigation, as the most effective way to increase food production in dry land, may not be readily available in the situation of drought. One of the alternatives is to supply plants with enough nutrients so that they can be more sustainable to the water stress. The objective of this study was to explore effects of irrigation and sulphur (S) application on water consumption, dry matter accumulation (DMA), and grain yield of winter wheat in NCP. Three irrigation regimes including no irrigation (rainfed, I 0) during the whole growth period, once irrigation only at jointing stage (90 mm, I 1), and twice respective irrigation at jointing and anthesis stages (90 mm plus 90 mm, I 2), and two levels of S application including 0 (S 0) and 60 kg ha-1 (S 60) were designed in the field experiment in NCP. Results showed that increasing irrigation times significantly increased mean grain yield of wheat by 12.5-23.7% and nitrogen partial factor productivity (NPFP) by 21.2-45.0% in two wheat seasons, but markedly decreased crop water use efficiency (YWUE). Furthermore, S supply 60 kg ha-1 significantly increased mean grain yield, YWUE, IWUE and NPFP by 5.6, 6.1, 23.2, and 5.6% (across two wheat seasons), respectively. However, we also found that role of soil moisture prior to S application was one of important greater factors on improving the absorption and utilization of storage water and nutrients of soil. Thus, water supply is still the most important factor to restrict the growth of wheat in the present case of NCP, S supply 60 kg ha-1 with once irrigation 90 mm at the jointing stage is a relatively appropriate recommended combination to improve grain yield and WUE of wheat when saving water resources will be considered in irrigated wheat farmlands of NCP.

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Background Heteropogon contortus is a valuable pasture species that is widely used for vegetation restoration in dry-hot valleys of China. However, to date, its morphological and physiological responses to drought, and the underlying mechanisms are not well understood. This study was aimed to investigate the morphological and physiological changes of H. contortus under drought stress during the dry-hot season. Heteropogon contortus was planted in pots and subjected to four levels of soil water treatments: above 85 % (control), 70–75 % (light stress), 55–60 % (moderate stress) or 35–40 % (severe stress) of field capacity.ResultsWithin the total stress period (0–29 days), H. contortus grew rapidly in the light stress, whereas severe stress had a negative impact on growth. Aboveground biomass decreased together with increasing drought stress, whereas root biomass increased. Consequently, the root/shoot ratio of the severe stress treatment increased by 80 % compared to that of the control treatment. The ratio of bound water/free water (BW/FW) was the most sensitive parameter to drought and showed a value under severe stress that was 152.83 % more than that in the control treatment. Although leaf water potential (LWP) and leaf relative water content (RWC) decreased with progressive water stress, H. contortus managed to maintain a relatively high RWC (nearly 70 %) in the severe stress condition. We also detected a significant reduction (below 0.6) in the ratio of variable fluorescence/maximum fluorescence (Fv/Fm) in the severe stress treatment.ConclusionsOur results show that H. contortus adapts to drought mainly by avoidance mechanisms, and its morphological and physiological characteristics are inhibited under severe stress, but can recover at a certain time after re-watering. These findings might help limited water resources to be fully used for vegetation management in the studied region.

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The hydrogeological investigation is a work carried out by comprehensive utilization of various exploration methods to identify hydrogeological conditions in the target area, and develop and utilize groundwater resources. There are great differences in hydrogeological conditions in different regions. Hence, it is necessary to take exploration technology according to local conditions to master hydrogeological information as much as possible. Among them, the remote sensing (RS) technology can reflect the ground surveying and mapping results with high efficiency and precision through the analysis of satellite or aerial photographs, which is a commonly used method in the current hydrogeological investigation. According to satellite RS data, this work evaluates the distribution of groundwater levels in the study area and explores the geological and hydrogeological conditions of the groundwater system in the affected area. Firstly, the human-computer interactive interpretation method is used to analyze the topography and geomorphology conditions. Secondly, the spectral characteristic curve analysis method is used to extract the spectral characteristics of regional stratum lithology, and analyze and determine the lithology composition and structure of the aquifer. Thirdly, the single-band and multiband models of soil moisture RS estimation of groundwater level are implemented. Finally, the measured data are employed to verify and analyze the estimated value of the model. The results are in line with the actual value, and good results have been achieved.