Grain yield,zinc efficiency and zinc concentration of wheat cultivars grown in a zinc-deficient calcareous soil in field and greenhouse

Field experiments were carried out to study grain yield, zinc (Zn) efficiency and concentrations of Zn in shoot and grain of 37 bread wheat (Triticum aestivum) and three durum wheat (Triticum durum) cultivars grown in a Zn-deficient calcareous soil with (23 kg Zn ha⁻¹), and without, Zn fertilization in 1993–1994 and 1994–1995. The same Zn-deficient soil was used in greenhouse experiments to study shoot dry weight, Zn efficiency and shoot Zn concentrations of 21 bread and three durum wheat cultivars (same cultivars used in the field experiments). Zinc fertilization of cultivars in the field enhanced grain yield on average by 30% in both years. Increases in grain yield to Zn fertilization varied substantially between cultivars from 8% to 76%. Accordingly, there was large variability in Zn efficiency of cultivars, expressed as the ratio of grain yield or shoot dry-matter yield produced under Zn deficiency compared to that under Zn fertilization. On average, Zn efficiency values ranged from 57% to 92% for grain yield in field experiments and from 47% to 83% for shoot dry weight in greenhouse experiments. Most of the cultivars behaved similarly in their response to Zn deficiency in the field and greenhouse. The cultivars selected from local landraces had both, a high Zn efficiency and high yield under Zn-deficient conditions. The bread wheat cultivars, improved for irrigated conditions, had generally low Zn efficiency and low yield, both in the field and greenhouse. All durum wheat cultivars in this study also showed low levels of Zn efficiency, grain yield and shoot dry weight under Zn deficiency. Overall, there was no relation between Zn efficiency values and Zn concentrations in grain or shoot dry matter. The results presented here demonstrate the existence of substantial variation in Zn efficiency among wheat cultivars, particularly bread wheat cultivars, and suggest that wheat landrace populations are a valuable source of genes to improve high Zn efficiency of wheat for Zn-deficient soils.     

Effects of Subsoiling to the Non-tilled Field of Wheat-Soybean Rotation on the Root System Development,Water Uptake,and Yield

Abstract

We introduced subsoiling to a field of wheat-soybean rotation where no-tillage practice had been conducted for five years and whose yield tended to decrease or stagnate. By subsoiling a half of each plot just before wheat sowing, treatments of tillage/no-tillage × subsoiling/no-subsoiling were established. Root distribution, shoot growth, water uptake and yield of both crops were examined to elucidate whether the subsoiling improves the productivity such as shoot biomass and yield through the modification of root system development, and how differ the effects of subsoiling between tilled and non-tilled fields. In wheat, roots were less concentrated in surface (0 ? 5 cm) layer in no-tillage, and distributed more in deep (20 ? 25 cm) layer of the soil. Deuterium labeled heavy water analysis revealed that the subsoiling enhanced water uptake from the deep soil layer in the no-tillage field. Both the no-tillage and subsoiling showed positive and significant effect on total biomass and yield. The effect of subsoiling must be related to water supply by deep roots in spring. In soybean no-tillage significantly increased the productivity, but subsoiling did not though distribution of the roots was modified by both practices. Soybean in non-tilled accumulated roots in the surface soil layer, but subsoiling did not significantly modify the root distribution especially in the deep soil layer. Water uptake trend and yield was thus not changed significantly by subsoiling. Subsoiling in the non-tilled field increased rooting depth and showed the possibility of braking yield stagnation in long-term no-tillage cultivation in wheat, but not in soybean.     

小麦根系生理活性时空分布与土壤有效养分的关系

为了解小麦根系生理活性时空分布与土壤有效养分含量的关系,在2019-2021年两个小麦生长季,于小麦的不同生育时期采用长方体铁盒(0.2 m×0.05 m×0.2 m)在麦行上、行距1/4处、行距1/2处分别取0～0.2 m和0.2～0.4 m土层的样品,测定不同位点小麦根系生物量、根系活跃吸收面积、根总吸收面积、根系活力,以及土壤碱解氮、有效磷和速效钾含量。结果表明,0～0.2 m和0.2～0.4 m土层中小麦根重密度、根总吸收面积和根系活跃吸收面积随生育时期的推进均呈先升后降的变化趋势;根系活力、根群生理势均呈“低-高-低-高-低”的变化趋势。0～0.2 m土层的根重密度、根总吸收面积、根系活跃吸收面积、根群生理势均显著高于0.2～0.4 m土层。在灌浆之前,0～0.2 m土层根系活力高于0.2～0.4 m土层;在灌浆到成熟期间,下层根系的根系活力显著增大。在整个生育期内,0～0.2 m土层中根重密度、根总吸收面积、根系活跃吸收面积和根群生理势的水平分布表现为行上>行距1/4处>行距1/2处;开花期之前,根系活力在行距1/4处最大,开花到成熟期间根系活力水平分布表现为行...     

意大利硬粒小麦和面包小麦推广品种对白粉病的抗性

本文介绍了意大利近年来小麦主要推广品种（80个硬粒小麦品种和7 3个面包小麦品种）1992－1996年在田间对白粉病的成株抗性情况，和13个意大利硬粒小麦和20个面包小麦品种及11个中国小麦品种（系）用意大利10个主要菌系进行的苗期抗性鉴定情况。在田间成株抗性监测中，12．2％和58．9％的硬粒小麦品种和面包小麦器分别表现抗病或中抗；在苗期抗性鉴定中，参试的很多中国品种（系）对大部分意大利菌株表现免疫、近免疫或高抗。由于意大利小麦品种或含有其亲本血缘的中国品种曾经在我国小麦育种和生产中起过比较重要的作用，因此希望这些信息对育种和植病工作者有所帮助。     

Deep rooting in winter wheat: rooting nodes of deep roots in two cultivars with deep and shallow root systems

Deep rooting of wheat has been suggested that it influences the tolerance to various environmental stresses. In this study, the nodes from which the deepest penetrated roots had emerged were examined in winter wheat. The wheat was grown in long tubes with or without mechanical stress and in large root boxes. The length and growth angle of each axile root were examined to analyze the difference in the vertical distribution of the roots between the two wheat cultivars, one with a deep and one with a shallow root system. In Shiroganekomugi, a Japanese winter wheat cultivar with a shallow root system, the rooting depths of the seminal and nodal roots decreased as the rooting nodes advanced acropetally. Six out of nine deepest roots were seminal root in the non-mechanical stress conditions. In Mutsubenkei, a Japanese winter wheat cultivar with a deep root system, grown in root boxes, not only the seminal roots but also the coleoptilar and the first nodal roots penetrated to a depth of more than 1.3 m in the root box, and became the deepest roots. In both cultivars, the seminal roots became the deepest roots under the mechanical stress conditions. There were no clear tendencies in the root growth angles among the rooting nodes in the wheat root system. This indicates that the length of the axile roots can explain the differences in the rooting depths among axile roots in a wheat root system. On the other hand, the axile roots of Mutsubenkei elongated significantly more vertically than those of Shiroganekomugi. This suggests that not only seminal but also nodal roots exhibit strong positive gravitropism and penetrate deeply in a cultivar with a deep root system. In wheat cultivars, it is likely that the extent of its Root Depth Index results partly from the gravitropic responses of both seminal and nodal roots.     

Root Growth and Water Extraction Response of Doubled-Haploid Rice Lines to Drought and Rewatering during the Vegetative Stage

Abstract

Doubled haploid lines (DHLs) of rice (Oryza sativa L.) were used to examine responses to drought and rewatering in controlled rainfed lowland conditions, in order to determine whether confounding by unrelated traits would be less than has been reported previously for contrasting cultivars that differ in genetic background. IR62266 and four DHLs derived from the cross between IR62266 and CT9993 (DHL-32, -51, -54 and -79) were grown in pot experiments in the greenhouse during the 2000 dry and wet seasons at IRRI, Los Baños, Philippines. There were two water regimes (well-watered and drought). Estimated water extraction obtained by time domain reflectometry (TDR) was similar to cumulative transpiration estimated from pot weighing for each genotype. Genotypic variation was observed in root traits and water extraction, with extraction slower in DHL-32 and faster in DHL-79, especially in deeper soil layers. An upper bound relationship between water extraction from a soil layer and root length density (RLD) in that layer was readily apparent over DHLs and soil depths, suggesting a critical value of RLD for water extraction of 0.30 cm cm^?3 in these conditions. Because soils in the field would not be as homogenous as the puddled soils used in these greenhouse experiments, this critical RLD for water extraction from a soil layer is a reference for ideal conditions, and requires careful validation in the field. Use of DHLs permitted comparisons with reduced confounding by genetic background, with consequent improvements in precision.     

轮耕对麦田土壤容重和小麦根系发育的影响

为给小麦生产中的合理轮耕提供参考依据,通过田间定位试验,研究了轮耕麦田土壤容重及小麦根系发育的变化。结果表明,与连续旋耕3年相比,旋耕2年后深耕处理降低了15～25cm土层土壤容重,对表层土壤容重影响相对较小,增加了不同层次土壤根量、生育中后期15～20cm土壤单株次生根数和根系活力。说明在黄淮平原当前普遍采用一年两熟种植制度和作物秸秆通过旋耕还田的耕作方式下,采取旋耕2年后深耕对于改善麦田土壤条件、促进小麦根系生长发育更为有利。     

Baking quality of emmer-derived durum wheat breeding lines

Durum wheat (Triticum turgidum L. var. durum) is used predominantly for pasta products, but there is increasing interest in using durum for bread-making. The goal of this study was to assess the bread-making potential of 97Emmer19, an Emmer wheat (Triticum turgidum L. var. dicoccum) and in breeding lines derived from crosses of 97Emmer19 with adapted durum wheat cultivars. 97Emmer19 and its progeny were evaluated in 2005 and 2006 along with five durum wheat cultivars. Three bread wheat (Triticum aestivum L.) cultivars were included as checks to provide a baseline of bread making quality observed in high quality bread wheat cultivars. 97Emmer19 exhibited higher LV than all the durum wheat checks and approached the LV achieved with the bread wheat cultivar ‘AC Superb’. Breeding lines derived from 97Emmer19 had higher LV than those of the durum wheat checks, confirming that this trait was heritable. In general, durum wheat cultivars with elevated gluten strength and/or increased dough extensibility were noted to have higher LV. Dough extensibility appeared to be a more critical factor as gluten strength increased. These results indicate that there is potential to select for genotypes with improved baking quality in durum breeding programs.     

普通小麦与其近缘种及人工合成材料根系主要性状的比较

为了解普通小麦与其近缘种和人工合成材料(八倍体小偃麦、小黑麦)根系性状的差异,时普通小麦、黑麦、野生一粒小麦、拟斯卑尔脱小麦、提莫菲维小麦、八倍体小偃麦、小黑麦和硬粒小麦根系主要性状进行比较分析.结果表明,近缘种、人工合成材料单株次生根数、根体积、根干重和根冠比在生育后期均显著大于普通小麦,根系活力和生育前期的根中可溶性糖含量也均显著高于普通小麦.近缘种和人工合成材料根中全氮含量整体上低于普通小麦.相关分析表明,根系一些主要性状与籽粒全氮含量相关显著或极显著.综合来看,近缘种、人工合成材料具有发根力强、根系活力高等优势,在小麦改良中具有重要利用价值.     

Physiology of the Potato: New Insights into Root System and Repercussions for Crop Management

Potato roots are concentrated mostly in the plow layer up to 30 cm in soil depth. Some roots extend up to 100 cm depth and the total root length throughout the soil profile reaches about 10–20 km m^?2 area. There are large differences in root mass (dry weight and length) in the plow layer between cultivars, breeding lines and wild relatives. The differences are generally stable across different environmental conditions, such as locations with different soil types, fertilizer rates and planting densities. Under favourable environmental conditions without severe shortage of water and nutrients, root mass differences between genotypes are related to maturity class: late genotypes continue root growth longer, and attain larger root mass and deeper rooting than early genotypes. Differences in root mass become clear at the start of flowering, much earlier than differences in shoot mass. Root mass is negatively correlated with early tuber bulking. However, root mass generally shows positive correlations with shoot mass and final tuber yield. Differences in root mass also exist amongst genotypes of the same maturity class. Using root mass in the plow layer and tuber yield as selection criteria, Konyu cultivars were bred in Japan. They showed significantly less reduction of leaf conductance and photosynthesis, leaf area and tuber yield than commercial cultivars under dry soil conditions. To assist breeding for root characters, new methods have been developed to assess the ability of roots to penetrate into hard soil layers using pots with paraffin-vaseline discs and the ability to absorb under low water potential in vitro. Physiological research on root characteristics contributed in the past, and will continue to do so in the future, to the development of new cultivars with high drought tolerance and to the improvement of irrigation practice.     

Differential feeding by grasshoppers and levels of foliar diseases in various cultivars of spring cereals

Sixty-four cultivars and strains of cereals were evaluated under field conditions for differential feeding by grasshoppers, (Orthoptera:: Acrididae) and for their resistance to foliar disease. Grasshoppers actively fed on all triticale and durum wheat lines, on 11 of 12 bread wheat lines, and on 11 of 24 barley lines. Both the incidence and severity of foliar disease were high in all cereals. There was no correlation between grasshopper damage and resistance to foliar disease (r+ −0·059) in the barley but a positive trend appeared in wheat lines (bread r= +0·487; durum r= +0·295). The data suggest that present trends in breeding disease-resistant cereal cultivars will not introduce increased susceptibility to grasshopper damage.     

Development and Distribution of Root System in Two GrainSorghum Cultivars Originated from Sudan under Drought Stress

Abstract

The difference in rooting pattern between two grain sorghum cultivars differing in drought tolerance was investigated under drought stress. The cultivars, Gadambalia (drought-tolerant) and Tabat (droughtsusceptible), were grown in bottomless wooden or acrylic root boxes to examine root parameters. Gadambalia consistently exhibited higher dry matter production and leaf water potential than Tabat under drought stress in both root boxes. In the experiment with wooden root boxes, under a drought condition, Gadambalia extracted more water from deep soil layers (1.1-1.5 m), which was estimated from the reduction in soil water content, than Tabat. This was because Gadambalia had a significantly higher root length density in these soil layers. The high root length density was due to enhanced lateral root development in Gadambalia. In the other experiment with acrylic root boxes, though total root length in the upper soil layer (0-0.5 m) was declined by limited irrigation in both cultivars, the reduction in Gadambalia was moderate compared with that in Tabat owing to the maintenance of fine root growth. Unlike Tabat, Gadambalia had an ability to produce the nodal roots from higher internodes even under drought, which resulted in the high nodal root length of Gadambalia. The growth angle of nodal roots was significantly correlated with root diameter, and the nodal roots from the higher internodes had large diameters and penetrated into the soil more vertically. These results indicate that the responses of roots (i.e. branching and/or growth of lateral root, and nodal root emergence from higher internodes) to soil dryness could be associated with the drought tolerance of Gadambalia.     

Root growth dynamics and stomatal behaviour of rice (Oryza sativa L.) grown under aerobic and flooded conditions

Aerobic rice culture is a new technology designed to reduce water use, but the vulnerability of rice to aerobic condition has limited its development. The objective of this study was to characterize the root growth and stomatal behaviour of four rice cultivars grown in flooded and aerobic culture for 2 years. In aerobic culture, where the soil water potential at 20-cm depth averaged between −15 and −30 kPa, total root biomass was significantly lower than in flooded culture for the whole growth period, owing to a reduction in root biomass in the surface layer. Dry-matter partitioning to roots decreased, but the ratio of deep root biomass to total root biomass tended to be higher in aerobic culture than in flooded culture. The low root-to-shoot ratio and poor root growth in the surface layer in aerobic culture are attributable to the considerable reduction in adventitious root number. As a result, the varietal difference in total root biomass was due largely to individual root growth in aerobic culture. Stomatal closure was distinct at the vegetative stage in aerobic culture, even when the soil water potential was near field capacity, partly because of the poor rooting vigour. When the soil water potential at 20-cm depth was below −50 kPa, the stomatal behaviour reflected the root growth in the subsurface layer. These results suggest the role of vigorous root growth in soil water uptake and hence, in maintaining transpiration in aerobic rice culture.     

Coleoptile length variation of near-isogenic Rht lines of modern CIMMYT bread and durum wheats

A set of 10 bread wheat (Triticum aestivum L.) and six durum wheat (T. turgidum L.) genotypes near-isogenic for either the Rht1 or Rht2 dwarfing genes were analyzed for plant height, kernel weight, coleoptile length and grain yield. Coleoptile length was measured at three different temperatures and plant height, kernel weight and grain yield determined in six different environments. Durum wheat, regardless of stature, produced longer coleoptiles than bread wheat at higher temperature. Within the non-Rht isolines, plant height and coleoptile length were independent characters. The tall durum wheats tended to be taller than their bread wheat counterparts, indicating an absence of minor genes for reduced height. However, a number of bread wheat cultivars showed relatively small height increases following removal of the Rht gene and substantially greater increases in coleoptile length. Coleoptile length was more highly correlated (r²=0.53, P<0.01) with seed weight among the non-Rht isolines compared to cultivars containing either Rht1 or Rht2. Grain yield and plant height were positively correlated among the semi-dwarf Rht isolines in 5 of 6 environments. No equivalent relationship existed among the non-Rht materials. Grain yield (standard sowing depth 3 cm) and coleoptile length were generally not significantly correlated within each isogenic grouping.

Plant breeders should be able to select short statured, non-Rht1 or non-Rht2 hexaploid bread wheat with better emergence characteristics. The non-Rht genotypes developed from the bread wheat cultivars Seri 82 and Culiacan 89 were identified as meeting these criteria. Wheats such as these could offer significant advantages to farmers in environments where deep sowing into stored soil moisture is practiced.     

土壤剖面硝态氮非均匀分布条件下小麦根系生长和氮素吸收特征

为探讨土壤硝态氮非均匀分布条件下小麦根系生长及氮素吸收特征,选用石麦15、衡观35、H10和L14等4个小麦品种为材料,进行土壤分层培养试验,模拟土壤剖面中上下层硝态氮空间分布差异,测定和分析了小麦根系长度、直径、分布等形态学特征及植株氮素含量和累积量。结果表明,当土壤中硝态氮施用量上层较低、下层较高时,小麦植株根系总长和表面积在上下土层中分布比值降低,根系趋向下层土壤生长。上下层土壤中硝态氮施用量均较高时,上下层土壤中的根系总长和表面积比值较大,根系趋向上层土壤生长。土壤剖面不同层次中硝态氮供应非均匀条件下,小麦根系发育呈现明显的可塑性反应。小麦根系总长和表面积以及直径≤0.15mm的细根长(占整个根系的比重很大)与植株地上部氮含量和氮素积累量极显著正相关,与土壤中硝态氮含量极显著负相关。     

Grain cadmium and zinc concentrations in wheat as affected by genotypic variation and potassium chloride fertilization

Thirteen bread wheat (Triticum aestivum L.) and two durum wheat (Triticum turgidum L. var. durum) cultivars were grown over six site-years to identify differences in grain Cd and Zn concentrations, as affected by genotypic variation and soil application of potassium chloride (KCl) fertilizer. Application of KCl fertilizer did not consistently affect grain Cd concentration of wheat cultivars, but increased average grain yield and decreased average grain Zn in 4 of 6 site-years. However, soil type and year had significant effects on grain Cd and Zn, indicating a strong environmental effect on grain quality. Grain concentrations of Cd and Zn were generally lower for the clay loam (CL) than the fine sandy loam (FSL) soils. The wheat cultivars showed significant genotypic differences in grain concentrations of Cd and Zn, suggesting the potential of breeding to reduce Cd and increase Zn concentrations in grain. The two durum cultivars contained high concentrations of Cd but not Zn compared to the bread wheat. The interaction between cultivars and site-years was significant for grain Zn, but not for grain Cd, suggesting that grain Cd is a more stable trait than grain Zn across environments. Grain Zn and Cd were not related to each other but they both correlated negatively with grain yield. The lack of relationship between Zn and Cd suggests that breeding for enhanced Zn concentration can be attained without necessarily affecting grain Cd concentration. The negative relationship between Cd and Zn concentration and dry matter yield was likely the result of biological dilution, suggesting that genetic improvement leading to increased yield may concurrently decrease mineral concentration. Results of this study are useful to improve the mineral composition of wheat used for human consumption through the development of cultivars and use of agronomic management practices that increase Zn and/or reduce Cd concentrations in wheat grain.     

Root size,distribution and soil water depletion as affected by cultivars and environmental factors

Field experiments were carried out in two parts at the Luancheng Experimental Station in the North China Plain. Part I, which was a continuous experiment that ran from 1990 to 2008, investigated the change of grain yield, evapotranspiration (ET), root size and soil water utilization of winter wheat (Triticum aestivum L.) under three water regimes (rain-fed, two and four irrigation applications). Part II used 10 cultivars released from 1970 to 2000 that were grown under the same condition for two seasons (2005/2006 and 2006/2007) to compare root size, root:shoot ratio and soil water depletion (SWD). The results of testing in Part I showed that the yield and ET of winter wheat gradually increased from 1990 to the present. There was no consistent change in total root length (TRL) over time. The difference in root size among seasons and irrigation treatments mainly occurred in the upper soil profile, where the root length density (RLD) was greater. No direct relationship was found between root size and soil water use. Thus, TRL was not a factor that indicated the water extracting capacity of crops. The results from Part II revealed that the seasonal ET of earlier released cultivars (ERC) was similar to that of recently released cultivars (RRC) under well-watered conditions. However, ET was slightly increased from ERC to RRC under water deficit conditions, indicating high soil water depletion by RRC. TRL decreased from ERC to RRC and was significantly correlated with plant height. The breeding of winter wheat that reduced plant height not only increased harvest index, but also reduced root size, resulting in a smaller root:shoot ratio. The reduction in TRL from ERC to RRC mainly occurred in the top soil profile. The results from both tests indicate that TRL is not a factor that determines soil water use; rather, the distribution of RLD along the soil profile plays more important role in soil water utilization. Smaller root size in the upper soil layer did not affect soil water uptake, and might be more economical in terms of production efficiency.     

Wheat stem sawfly (Cephus pygmaeus L.) damage; impacts on grain yield, quality and marketing prices in Anatolia

This study aimed to draw the attention of the all stake holders attention to an underestimated insect pest of wheat in Southeastern Anatolia. The field studies were carried out in the experimental field of GAP Training, Extension and Research Center in Koruklu in 2003–2004 cropping season.

It was found that the number of sawfly damaged spikes varied between 6 and 12% in durum wheat and 8 and 12% in bread wheat. Comparing healthy grains, grain weight spike⁻¹ decreased significantly, giving 0.430 g less kernel weight in durum wheat and 0.385 g in bread wheat. Some of the grain quality characteristics of both sawfly damaged and healthy spikes were tested and it was found that protein content (%) in durum wheat, and 1000 kernel weight in bread wheat were reduced significantly, whilst, the SDS sedimentation value in bread wheat increased significantly for sawfly damaged grains. Grain yield losses by sawfly infestation were found to be 2.23% in durum wheat and 3.32% in bread wheat. Marketing price studies showed that sawfly damage reduced it significantly, resulting in $ 0.016 kg⁻¹ less price in bread wheat. But this was not serious for durum wheat.

It was concluded that income loss, depending on grain yield loss, un-harvestable broken spikes and lower marketing price of sawfly damaged grains, could be no less than $ 68.8 ha⁻¹ in durum wheat and $ 68.6 ha⁻¹ for bread wheat. Therefore, some control methods are required for sawfly infestation, where damage is already over the economic threshold (10–15% stem cut by pest) especially in bread wheat.     

甘蔗家系根系性状与地上部性状相关性分析

以甘蔗20个组合实生苗为材料,用盆栽和大田试验研究甘蔗家系根系性状与地上部性状的关系。结果表明:根长与根表面积、根体积变化呈极显著相关;根长、根表面积、根直径、根体积与实生苗新植的株高、径茎、锤度、成活率呈极显著或显著相关;其中,根长、根表面积、根体积与宿根株高呈显著相关;根体积与宿根理论产量呈显著相关。