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1.
Drought is one of the major environmental stresses altering forest productivity. However, nutrient availability can modulate drought resistance. Phoebe zhennan (gold Phoebe) is a high‐quality timber‐producing but threatened tree species in China, facing serious anthropogenic disturbances and abiotic constraints that restrict its growth and development. However, little attention has been given to designing adaptive strategies for its management by evaluating the possible role of major nutrients, particularly nitrogen (N), on its morphological and physio‐biochemical responses under water stress. To evaluate these responses, a complete randomized design was followed to investigate the effects of two irrigation levels (well‐watered and drought‐stressed conditions) and N fertilization treatments (with and without N). Drought stress significantly affected the growth of seedlings, as indicated by impaired photosynthesis, pigment degradation, disrupted N metabolism, over‐production of reactive oxygen species and enhanced lipid peroxidation. Nitrogen supplementation under drought stress had remarkable positive effects on the growth through physio‐biochemical adjustments as shown by higher level of nitrogenous compounds and up‐regulation of N‐associated metabolic enzymes activities which might be due to N‐mediated improved leaf relative water contents and photosynthetic efficiency. In addition, N application reduced oxidative stress and membrane damage, and maintained a high accumulation of osmolytes. However, in well‐watered seedlings N fertilization significantly improved root biomass and net CO2 assimilation rate suggesting high N‐use efficiency of the seedlings. These findings reveal that drought significantly affects the growth of P. zhennan, while N fertilization plays a crucial role in alleviating water stress damage by improving its drought tolerance potential at low metabolic costs. Therefore, N fertilization could be considered as an effective strategy for the conservation and management of P. zhennan in the face of future climate change.  相似文献   
2.
ABSTRACT

Soil macrofauna is vital for soil functions and soil-mediated processes in all ecosystems. However, environmental perturbations, such as drought, that threaten both the abundance and function of soil macrofauna remain mostly unexplored, particularly in an agroforestry system. We investigated the effects of drought on soil macrofauna abundance and vertical distribution under three different planting systems including two intercropping systems, comprising Chinese prickly ash (Zanthoxylum bungeanum) intercropped with soybean (Glycine max) (Z-G) or bell pepper (Capsicum annuum) (Z-C), and one monoculture system, comprising only Z. bungeanum (Z). Soil samples were collected at depths of 0–10, 10–20, and 20–30 cm, and soil macrofauna and chemical properties were analyzed. Soil dryness negatively affected soil macrofauna in all planting systems. Drought reduced the total macrofauna density, biomass, genera richness, and Pielou’s evenness. Additionally, drought significantly decreased density and biomass of Drawida and Eisenia but had no effect on Carabid beetles. Soil macrofauna density was highest in the Z-G intercropping system and higher at 0–10 cm than at other soil depths. These results indicate that intercropping soybean rather than bell pepper increases the abundance and biomass of soil macrofauna, and drought remarkably impacts the response of soil macrofauna to planting systems.  相似文献   
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4.
Rice flour composition played a key role in determining the changes in pasting properties of rice flour. The influence of incorporating defatted rice bran (DFRB), rice bran fiber (RBF), rice bran protein (RBP), and stabilized rice bran (SRB) fractions on the mechanism of rice flour pasting viscosities was investigated. Pasting properties of long‐ and medium‐grain rice flour substituted with 5, 10, 15, 20, and 100% bran fractions resulted in a significant decrease (P < 0.05) in rice flour pasting property values. Flour substituted with RBP had the lowest pasting property measurements compared with other fractions, and the greater the percentage substituted, the lower the pasting property values. DFRB and RBF were least affected properties when used as a replacement. Results were attributed to the contribution of rice starch in the mechanism of rice paste formation, in which decreasing starch in a rice flour sample, as a result of substituting with fractions of SRB, may have resulted in faster swelling of starch granules to the maximum extent and increased their susceptibility to be disrupted by shear, resulting in low paste viscosities. Results also suggested that protein structural integrity and the nature of starch–protein bonding affected rice flour pasting mechanism formation.  相似文献   
5.
Genetic Resources and Crop Evolution - Alliums comprise of popular spices and used for various culinary purposes and nutraceuticals. Poor genetic characterization and scarce information regarding...  相似文献   
6.
□ Growth and nutrient acquisition of tomato (Lycopersicon esculentum L.) cv ‘Amani’ were studied under induced salt stress in Hoagland's solution. The plants were treated for 37 days with salinity induced by incorporating different concentrations [0.0 (control), 50, 100, 150, or 200 mM] of sodium chloride (NaCl) to the nutrient solution. Slight reduction was obtained in growth represented by (shoot length and number, leaf number, and dry weight) when seedlings were directly exposed to NaCl stress from 0.0 to 100 mM. At higher concentrations (150 or 200 mM), growth parameters were adversely affected and seedlings died thereafter. Elevated salinity significantly reduced crude protein and fiber in shoots and roots. Tomato shoot and root contents of potassium (K), iron (Fe), and ash were reduced significantly in response to increased levels of salinity. Tissue contents of sodium (Na) and chloride (Cl) increased with elevated salinity treatments.  相似文献   
7.
Gene pyramiding (assembling multiple desirable genes into a single genotype) via conventional methods to combat Asian rust resistance in soybean (Glycine max (L.) Merrill) and developing soybean varieties with durable resistance to this disease continues to be a challenge. Therefore, our objectives were to pyramid four Asian rust (caused by Phakopsora pachyrhizi) resistance (Rpp) genes, viz., Rpp1, Rpp2, Rpp3, and Rpp4 from their respective donors, PI200492 (Komata), PI230971, PI462312 (Ankur), and PI459025 (Bing Nan). Two single crosses (PI200492 × PI230971; PI462312 × PI459025) and a double-cross [(PI200492 × PI230971) × (PI462312 × PI459025)] were made for present study. The scoring of parents and crosses was done according to a 0–9 grading scale, where 0 = 0% disease intensity (absolutely resistant), 1 = 1% disease intensity (highly resistant), 3 = 1.1–10% disease intensity (moderately resistant), 5 = 10.1–25% disease intensity (moderately susceptible), 7 = 25.1–50% disease intensity (susceptible), and 9 = more than 50% disease intensity (highly susceptible). Out of four parents used, Rpp1 gene-donor plant introduction (PI)200492 (Komata) was immune to rust, with a disease grade of 0.92. Rpp2 and Rpp4 gene donors, PI230971 and [PI459025 (Bing Nan)], had reddish-brown (RB) lesions. Rpp3 gene-donor PI462312 (Ankur) showed a few, highly localized patches of tan lesions; however, it was not as susceptible as the susceptible check JS335. In cross-A (PI200492 × PI230971), all the F1s were rust resistant, whereas in the F2, 93.9% (845 plants) were either immune (11.0%, 99 plants) showing no infection or had RB lesions (82.9%, 746 plants) with resistant reaction and the remainder 6.1% (55 plants) had susceptible reaction. In cross-B (PI462312 × PI459025), 80.8% (63 plants) of the F1 had RB lesions and resistant reaction, whereas 19.2% (15 plants) had susceptible reaction. In its F2 population, 24.2% (217 plants) were susceptible. In cross-C [(PI200492 × PI230971) × (PI462312 × PI459025)], i.e., double-cross hybrid (DCH), 85.5% (77 plants) were either immune or had RB lesions, whereas the rest of the plants 14.5% (13 plants) showed susceptible reaction. Based on parental survey, four simple sequence repeat primers were short-listed for amplification of individual rust-resistance gene-specific markers in ten plants of each cross, viz., Satt191-210bp (Rpp1 gene), Sat_361-245bp (Rpp2 gene), Satt263-195bp (Rpp3 gene), and Rpp4TM-128bp (Rpp4 gene). In the single-cross hybrid (SCH)-A (PI200492 × PI230971), six plants had both Rpp1 and Rpp2 genes, whereas in another SCH-B (PI462312 × PI459025), seven plants had both Rpp3 and Rpp4 genes. In DCH [(PI200492 × PI230971) × (PI462312 × PI459025)], a single plant had all four Rpp genes, five plants had two Rpp genes, whereas a single susceptible plant had only Rpp3 gene. The homozygous rust-resistant segregants from these crosses can be used for improving rust resistance of otherwise adapted, high-yielding soybean genotypes.  相似文献   
8.
Aim of the present research is to investigate the effect of nitrogen (N) and phosphorus (P) on soil food webs (microbes, nematodes and microarthropods) trophic interactions in agriculture ecosystems. A complete randomized block design experiment of N and P fertilization was initiated in 2010 with four treatments: (1) P-addition, (2) N-addition, (3) NP-addition and (4) control. After 4 years of fertilization, compared with control, N-addition had a negative effect on microarthropods and clarify indirectly by significantly (P < 0.05) increasing soil total nitrogen (0.37 g kg?1) and available nitrogen (20.03 mg kg?1). The reduction in microarthropods resulted significant (P < 0.05) increase in bacterivores and fungivores feeding on bacteria and fungi, an example of top-down control. P-addition had indirect negative effects on microarthropods by means of significantly (P < 0.05) increasing soil total phosphorus (0.62 g kg?1) and available phosphorus (24.17 mg kg?1), aggravated fungivores feeding on fungi and strengthened top-down control. NP-addition significantly (P < 0.05) increased total microbial biomass, nematodes and microarthropods and resulted in bottom-up control. These results suggested that top-down effects were the dominant force in N- or P-addition treatments. NP-addition strengthened bottom-up control by enriching food resource. Unbalance fertilization could pose adverse on agricultural soil ecosystem and yield potential of crops.  相似文献   
9.
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10.
In Indian mustard (Brassica juncea L. Czern & Coss), a major oilseed brassica crop, oil yield is the ultimate trait of economic value, which is determined by seed yield (SY) and oil content (OC). SY, the end product of many complex biological processes, is influenced by many traits, such as plant height (PH), branch number, siliqua number, seed weight, seed size and pod length. It is difficult to accurately select for high-yielding genotypes based exclusively on SY, neglecting other yield-determining traits in commercial breeding programs. Therefore, it is desirable for breeders to simultaneously improve several traits of economic importance, most of which are quantitative in nature. The purpose of the present study was to develop selection indices for simultaneous selection of multiple quantitative traits to enhance selection efficiency of the mustard breeding program of Punjab Agricultural University (PAU) located in Abohar, Punjab. A set of 487 diverse mustard genotypes, comprising germplasm accessions of Indian and European origin, advanced breeding lines, landraces, and cultivars, was evaluated using an alpha lattice design for 2 years (2015–16 and 2016–17) at the Regional Research Station of PAU, Abohar, District Fazilka (the major mustard-growing region of the Punjab state). Data on PH, main shoot length (MSL), number of primary branches (NPB), number of secondary branches (NSB), number of siliquae on main shoot (NSMS), siliqua length (SL), number of seeds per pod (NSP), 1000-seed weight (TSW), SY on a plot basis and OC were recorded. To compute selection indices, economic weights, as determined via path coefficient analysis, were assigned to major yield-determining traits. Out of eight recorded agronomic traits, four traits, viz., NSMS, TSW, NSB and NPB, had larger direct effects on SY than other traits, and hence were assigned relative economic weights of 0.60, 0.20, 0.12 and 0.08, respectively. Selection indices were computed using different combinations of traits via Kang_SASPath computer program. When seven traits were used in a selection index (PH, NPB, NSB, NSMS, SY, TSW and MSL; or PH, NPB, NSB, NSMS, SY, TSW and OC), expected genetic advance (GA)at 5% selection intensity was about the same (9.55; selection efficiency or SE = 163% compared with selection based on SY alone).The GA was 9.46 (SE = 161%)for five traits, viz., NPB, NSB, NSMS, SY and TSW; and 9.30 (SE = 159%)for four traits, viz., NPB, NSB, NSMS, and TSW. These GAs were compared with the GA for SY only, which was 5.90 (benchmark; SE = 100%). We concluded that simultaneous selection based on multiple traits was always more efficient than selection based on SY alone. As there was only a small difference between the GA based on four traits (SE = 161%) and GA based on seven traits (SE = 163%), we suggest that mustard breeders use the parsimonious combination of four traits, viz., NPB, NSB, NSMS, and SY, to enhance SY and, consequently, oil yield in mustard.  相似文献   
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