大麦籽粒总花色苷含量的遗传变异及其与粒色的相关分析

有色大麦较普通大麦含有较多花色苷等活性成分,具有较好的保健和辅助治疗功能。为了解大麦籽粒花色苷的遗传特点,选育高花色苷含量的大麦新品系,本研究以紫光芒裸二棱×Schooner构建的193个重组自交系为材料,测定3个试点[玉溪(2013年)、白邑(2014年)及嵩明(2015年)]的大麦籽粒总花色苷含量和粒色,分析大麦籽粒总花色苷含量的遗传变异及其与粒色的相关性。结果表明,大麦RIL群体籽粒总花色苷含量遗传变异大,3个试验点大麦总花色苷含量变异范围分别为0.36~1.38、0.50~1.50、0.50~1.58 mg·g^-1,变异系数为25.00%~33.85%。大麦总花色苷含量呈右偏态、尖顶峰分布,由主效基因控制遗传。高海拔冷凉气候在一定程度上有利于大麦籽粒总花色苷含量累积。3个试点大麦总花色苷含量与粒色均呈极显著正相关,表明大麦籽粒颜色越深,其总花色苷含量越高。与紫光芒裸二棱相比,3个试点有8个共同株系(27、34、35、37、38、60、138、167)的总花色苷含量显著或极显著提高。本研究结果为高花色苷含量大麦种质创新及育种提供了一定的理论依据。     

Determination of unsaturated soil hydraulic properties at different applied tensions and water qualities

Irrigation with low-quality water may change soil hydraulic properties due to excessive electrical conductivity (EC_w) and sodium adsorption ratio (SAR_w). Field experiments were conducted to determine the effects of water quality (EC_w of 0.5–20 dS m^?1 and SAR_w of 0.5–40 mol^0.5 l^?0.5) on the hydraulic properties of a sandy clay loam soil (containing ～421 g gravel kg^?1 soil) at applied tensions of 0–0.2 m. The mean unsaturated hydraulic conductivity [K(ψ)], sorptive number (α) and sorptivity coefficient (S) varied with change in EC_w and SAR_w as quadratic or power equations, whereas macroscopic capillary length, λ, varied as quadratic or logarithmic equations. The maximum value of K(ψ) was obtained with a EC_w/SAR_w of 10 dS m^?1/20 mol^0.5 l^?0.5 at tensions of 0.2 and 0.15 m, and with 10 dS m^?1/10 mol^0.5 l^?0.5 at other tensions. Changes in K(ψ) due to the application of EC_w and SAR_w decreased as applied tension increased. Analysis indicated that 13.7 and 86.3% of water flow corresponded to soil pore diameters <1.5 and >1.5 μm, respectively, confirming that macropores are dominant in the studied soil. The findings indicated that use of saline waters with an EC of <10 dS m^?1 can improve soil hydraulic properties in such soils. Irrigation waters with SAR_w < 20 mol^0.5 l^?0.5 may not adversely affect hydraulic attributes at early time; although higher SAR_w may negatively affect them.     

Requirement of rice crop for phosphorus and potassium at varying sodicity levels

Abstract

Rice (Oryza sative L.) plants were grown in pots in soil at pH 8.0, 9.4 9.8, and 10.0 to study the response to phosphorus (P) and potassium (K) fertilization at the rate of 60 kg/ha alone or in combination on growth, yield attributes, and chemical composition of the shoot. Increasing sodicity stress (pH 8.0, 9.4, 9.8, and 10.0 achieved by using sodium bicarbonate) adversely affected growth with delayed initiation of tillering and reduced the grain filling period. Total and filled grains per panicle, 1,000 grain weight, and grain yield were significantly lowered even at pH 9.4. Analyses of the shoot at 30 days after transplanting and at maturity showed a pronounced increase in Na concentration with a decrease in ? and calcium (Ca). Phosphorus and magnesium (Mg) were slightly higher in the shoot in response to sodicity stress. Fertilization with ? and ? at pH 10.0 helped plants to offset the ill effect of sodicity by early initiation of tillering and flowering and had a positive response on the yield attributes and grain yield. This also resulted in a decrease in Na and improvement in the ? and ? status of shoot. It was concluded that the amount of available ? and ? in the soil which was adequate for plant growth and development at lower sodicity levels, however became inadequate at higher sodicity.     

Growth,transpiration, root‐born cytokinins and gibberellins,and nutrient compositional changes in sesame exposed to low root‐zone temperature under different ratios of nitrate: Ammonium supply

The growth of sesame (Sesamum indicum L.) was studied at three root temperature regimes (25/25, 20/10 and 15/15°C day/night) factorially combined with three NO₃ ^‐: NH₄ ⁺ ratios (mM ratios, 10:0, 8:2, or 6:4), as a source of nitrogen (N), in the irrigation solution. The air temperature was kept constant at 30°C. Transpiration, nutrient composition, and level of root‐born cytokinins and gibberellins in the xylem exudate were monitored. The two low root temperature regimes, 15/15 and 20/10°C, restricted the growth of sesame, reduced transpiration and increased the accumulation of soluble carbohydrates in the shoot and in the roots compared to the 25/25°C regime. The NO₃:NH₄ ⁺ ratios had no effect on growth. Nutrient contents in the shoot at low root temperatures, particularly K⁺, NO₃ ^‐, and H₂PO₄ ^‐ were decreased markedly, but Na⁺ increased relative to it's content in the 25/25°C regime. Increasing NH₄ ⁺ proportion in the irrigation solution raised total N concentration in the plant tissues at all root temperatures. The amounts of cytokinins and gibberellins in the xylem exudate decreased at the low root temperature regimes relative to the 25/25°C regime. Low root temperature reduced xylem transport of nutrients and root born‐phytohormones, most probably because of reduced water flow through the plant relative to the 25/25°C regime.     

Interspecific Facilitative Root Interactions and Rhizosphere Effects on Phosphorus and Iron Nutrition Between Mixed Grown Chickpea and Barley

A glasshouse study was conducted to investigate the effects of interspecific complementary and competitive root interactions and rhizosphere effects on phosphorus (P) and iron (Fe) nutrition of mixed grown chickpea (Cicer arietinum L.) and barley (Hordeum vulgare L.). In order to provide more physiological evidence on the mechanisms of interspecific facilitation, we determined phosphatase activities in plant and rhizosphere, and root ferric reducing capacity (FR), Fe-solubilizing activity (Fe-SA) and rhizosphere pH. The results of the experiment revealed that biomass yield of barley was significantly increased by associated chickpea as compared to monocultured barley, while mixed cropping caused a slight decreases in the biomass yield of chickpea. The rhizosphere was strongly acidified under chickpea and chickpea/barley mixed cropping and this acidification, in turn, increased the available P, Fe(II) and DTPA-Fe concentrations in the rhizosphere. Fe-solubilizing activity (Fe-SA) and ferric reducing (FR) capacity of the roots were higher in both species grown in mixed culture relative to their monoculture which may improve Fe nutrition of both species. Leaf acid phosphatase (APase, EC 3.1.3.2) activity was higher in both plants under mixed cropping that may improve P nutrition of barley by chickpea.     

Phosphorous and Mung Bean Residue Incorporation Improve Soil Fertility and Crop Productivity in Sorghum and Mungbean-Lentil Cropping System

ABSTRACT

In sorghum and mungbean – lentil cropping system, field experiments were conducted for three successive years to assess the effect of mung bean residue incorporation on sorghum and succeeding lentil productivity along with different doses of phosphorus (P; 0, 30, 60 kg ha^{? 1}) applied to these crops. The level of soil fertility was also tested with or without incorporation of mung bean residue. The interaction of phosphorus to mungbean residue incorporation was thus studied in relation to improve crop productivity with balancing fertilizer requirements through an eco-friendly approach. Sorghum grain yield increased significantly when 60 kg P₂O₅ ha^{? 1} was applied and mungbean residue incorporated. The response was reduced to 30 kg P₂O₅ ha^{? 1} when mungbean residue was not incorporated. The succeeding lentil crop responded up to 60 kg P₂O₅ ha^{? 1} only when preceding sorghum crop received 0 or 30 kg P₂O₅ ha^{? 1}. Response to applied P₂O₅ to lentil reduced to 30 kg ha^{? 1} when preceding sorghum crop received 60 kg P₂O₅ ha^{? 1} and mungbean residue incorporated. Available soil nitrogen, phosphorus, and organic carbon content increased when mungbean residue was incorporated; however, available potassium (K) of the soil decreased from its initial value.     

Glycosidases in soils as affected by cropping systems

Glycosidases are a group of soil enzymes that play a major role in degradation of carbohydrates. This study was conducted to assess the impact of crop rotation and N fertilization on the activities of α‐ and β‐glucosidases and α‐ and β‐galactosidases in plots of two long‐term field experiments at the Clarion‐Webster Research Center (CWRC) and Northeast Research Center (NERC) in Iowa. Surface‐soil (0–15 cm) samples were taken in 1996 and 1997 in corn (Zea mays L.), soybean (Glycine max (L.) Merr.), oats (Avena sativa L.), or meadow (alfalfa) (Medicago sativa L.) plots that received 0 or 180 kg N ha^–1, applied as urea before corn, and an annual application of 20 kg P ha^–1 and 56 kg K ha^–1. Activities of the four glycosidases were significantly affected by crop rotations in both years at the two sites but not by nitrogen application. In general, higher activities were observed in plots under meadow or oat and the lowest in continuous corn (CWRC) and soybean (NERC). Four‐year rotation showed the highest activity, followed by 2‐year rotation and monocropping systems. Linear‐regression analyses indicated that, in general, the activities of the glycosidases were significantly correlated with microbial‐biomass C (r > 0.302, p ≤ 0.05) and microbial‐biomass N (r > 0.321, p ≤ 0.05), organic‐C (r > 0.332, p ≤ 0.05) and organic‐N (r > 0.399, p ≤ 0.01) contents of the soils. Results of this work suggest that multicropping stimulated the activities of the glycosidases. The specific activities of the glycosidases in soils of the two sites studied, expressed as g p‐nitrophenol released per kg of organic C, differed among the four enzymes. The lowest values were obtained for β‐galactosidase and α‐glucosidase, followed by α‐galactosidase and β‐glucosidase.     

Impact of foliar-applied Hoagland’s nutrient solution on growth and yield of mash bean (Vigna mungo L.) under different growth stages

In a field experiment, various strengths of Hoagland’s nutrient solutions were sprayed to mitigate the deleterious effects of nutrient stresses at different growth stages on mash bean cultivars. Hoagland’s nutrient solution strengths of 0, 25, 50, and 75% were applied at 7, 14, and 21?days after emergence on mash bean cultivars namely Mash-2 and Mash-88. Hoagland’s nutrient solution of 75% strength markedly increased the growth and yield of mash bean cultivars if applied at 21?days after crop emergence. The Mash-88 showed superiority in terms of growth and yield traits as compared to Mash-2. The results suggested that growth and yield was not enhanced effectively by a low strength of Hoagland’s nutrient solution applied at initial growth stages. It is concluded that foliar-applied Hoagland’s nutrient solution of 75% strength can be used as an efficient tool when applied at appropriate growth stage (21?days after emergence) to get optimal yield.     

Using fuzzy clustering algorithms to describe the distribution of trace elements in arable calcareous soils in northwest Iran

Accumulation of trace elements in arable soils is an important global hazard worldwide. In this research, the available content of Zn, Fe, B, Co, Cu, Mn, Mo and other soil parameters (pH, organic carbon content, carbonates and electrical conductivity) were analysed in northwest Iran. Concentration levels of trace elements were relatively low in areas with high pH values and low organic matter content, and only the Mo value exceeded the reference threshold. Based on the correlation among the elements, two datasets were produced. The first consists of Fe and Mn data, while the second contains Zn, B, Co, Cu and Mo data. Two fuzzy clustering approaches, Fuzzy C-means (FCM) and Gustafson–Kessel (GK), were applied for clustering both datasets. Multiple accumulation of trace elements was investigated from the clustering results and then visualized in spatial regionalization maps. The fuzzy clustering evaluating indices showed that the GK method was more appropriate than FCM for clustering datasets. The results revealed that the first and second datasets were divided into seven and six clusters, respectively. Fuzzy clustering analyses combined with geostatistical methods were used to map the spatial variability of each cluster. This method enabled the monitoring of multiple metal accumulation in large agricultural soils.     

Analysis of wild sunflower (Helianthus annuus L.) root exudates using gas chromatography‐mass spectrometry

Plant root systems mediate ecological processes in the rhizosphere through the exudation of organic compounds. Although exudate composition is thought to depend strongly on plant nutrient status, little is known about the influence of multi‐nutrient stresses. In this study, we examined responses to short‐term (3 d) nutrient limitation in Helianthus annuus (common sunflower), and root exudates were collected for 2, 4, or 6 h with the trap‐solution method. Root exudates, analyzed by means of gas chromatography‐mass spectrometry, consisted of over 60 sugars, sugar alcohols, amino acids, organic acids, and phosphates, with sugars and organic acids generally detected in the highest quantities. Twenty‐five of the detected metabolites, including half of the organic acids, sugars, and sugar alcohols, differed in relative abundance among the three sampling intervals, exhibiting higher abundance in sampling intervals greater than 2 h. Similarly, 24 of the detected metabolites, including half of the amino acids, phosphates, and sugar alcohols, were affected by nutrient supply, with 20 exhibiting higher abundance in the high‐nutrient treatment. Fumaric acid, quinic acid, and glucose were detected at significantly higher levels in the low‐nutrient treatment, potentially representing an adaptive response to nutrient limitation in sunflower. However, as sampling interval exerted a strong influence on the apparent effects of nutrient supply, future studies should consider the potential impacts of sampling‐interval length in comparative analyses of genotypes or treatments.