Differential tolerance to Fe and Zn deficiencies in wheat germplasm

Tolerance to Fe deficiency of wheat genotypes exhibiting differential tolerance to Zn deficiency is not known, even though the relationship between Fe nutrition and differential tolerance of wheat genotypes to Zn deficiency has been hypothesised frequently. In the present experiment, eight Triticum aestivum and two T. turigidum L. conv. durum cultivars were grown in nutrient solution deficient in either Znor Fe. Three indices of tolerance to nutrient deficiency were compared: relative [(-nutrient/+nutrient) × 100] shoot growth, shoot dry weight under nutrient deficiency and relative shoot/root dry weight ratio. Genotypes Aroona, Excalibur, Stilleto and Trident were classified as tolerant to both Zn and Fe deficiency, while durum wheats Durati and Yallaroi were sensitive to Zn deficiency and moderate to sensitive to Fe deficiency. Genotypes Excalibur, Stilleto and Trident come from the same breeding programme and have the common parent (line MEC3 =Sonora64//TZPP/YAQUI54) that could have been the donor of the genes for tolerance to Zn deficiency. When Fe-deficient, all wheat genotypes were severely chlorotic but kept producing shoot and root dry matter at a relatively high rate, making the relationship between the relative shoot growth and the relative leaf chlorophyll content poor. This is the first report of wheat genotypes exhibiting multiple tolerance to Zn and Fe deficiencies. This revised version was published online in July 2006 with corrections to the Cover Date.     

锌胁迫对不同耐低磷玉米生长及磷、锌养分吸收的影响

用营养液培养方法研究了不同耐低磷玉米幼苗对缺锌胁迫的适应性差异.结果表明,低磷敏感基因型在缺锌时植株各部位锌含量和吸收量显著下降,且变幅均明显高于耐低磷基因型.缺锌处理影响玉米幼苗的磷含量,低磷敏感基因型地上部磷含量较对照显著上升,根系磷含量变幅不大;耐低磷基因型地上部磷含量变幅较小,根系磷含量则显著下降.低磷敏感基因型在缺锌时地上部磷利用率显著下降,根系磷利用率无明显变化,而耐低磷基因型的变化情况正好相反,根系磷利用率受影响的程度大于地上部.     

Identification of pearl millet [Pennisetum glaucum (L.) R. Br.] lines tolerant to soil salinity

Crop tolerance to salinity is of high importance due to the extent and the constant increase in salt-affected areas in arid and semi-arid regions. Pearl millet (Pennistum glaucum), generally considered as fairly tolerant to salinity, could be an alternative crop option for salt affected areas. To explore the genotypic variability of vegetative-stage salinity tolerance, 100 pearl millet lines from ICRISAT breeding programs were first screened in a pot culture containing Alfisol with 250 mM NaCl solution as basal application. Subsequently, 31 lines including many parents of commercial hybrids, selected from the first trial were re-tested for confirmation of the initial salinity responses. Substantial variation for salinity tolerance was found on the basis of shoot biomass ratio (shoot biomass under salinity/ non-saline control) and 22 lines with a wide range of tolerance varying from highly tolerant to sensitive entries were identified. The performance of the genotypes was largely consistent across experiments. In a separate seed germination and seedling growth study, the seed germination was found to be adversely affected (more than 70% decrease) in more than half of the genotypes with 250 mM concentration of NaCl. The root growth ratio (root growth under salinity/control) as well as shoot growth ratio was measured at 6 DAS and this did not reflect the whole plant performance at 39 DAS. In general, the whole plant salinity tolerance was associated with reduced shoot N content, increased K⁺ and Na⁺ contents. The K⁺/Na⁺ and Ca⁺⁺/Na⁺ ratios were also positively related to the tolerance but not as closely as the Na⁺ content. Therefore, it is concluded that a large scope exists for improving salt tolerance in pearl millet and that shoot Na⁺ concentration could be considered as a potential non-destructive selection criterion for vegetative-stage screening. The usefulness of this criterion for salinity response with respect to grain and stover yield remains to be investigated.     

不同基因型冬小麦幼苗对缺锌的敏感性反应

采用砂培试验研究了不同小麦基因型对施锌的反应.通过比较小麦幼苗根冠比的大小(是否大于1),以及根据培养过程中植株的生长表现,将供试的25种小麦基因型划分为两类:即缺Zn敏感型和非敏感型.结果还表明,供Zn可以促进小麦地上部和根系的生长,均较大幅度提高了叶绿素SPAD值(25个小麦基因型中18个的增幅都超过10%),而根冠比则相对保持稳定.小麦种子中的锌含量、幼苗根冠比与小麦叶片叶绿素SPAD值之间均无显著性相关关系.由于地上部积累了较高浓度的Zn,缺Zn非敏感型可有效减轻缺Zn对其造成的危害.非敏感型与敏感型相比较,缺Zn条件下地上部和根系锌含量平均值分别高出96.6%和28.8%,而在供Zn条件下则高出47.6%和10.9%.施Zn对敏感型与非敏感型小麦体内磷含量并无显著性影响.小麦幼苗中P/Zn的大小主要受到小麦体内Zn含量变化的影响,与磷含量则无明显的关系.     

Identification and Characterization of Salt Tolerance of Wheat Germplasm Using a Multivariable Screening Approach

Salinity is one of the major limitations to wheat production worldwide. This study was designed to evaluate the level of genetic variation among 150 internationally derived wheat genotypes for salinity tolerance at germination, seedling and adult plant stages, with the aim of identifying new genetic resources with desirable adaptation characteristics for breeding programmes and further genetic studies. In all the growth stages, genotype and salt treatment effects were observed. Salt stress caused 33 %, 51 % and 82 % reductions in germination vigor, seedling shoot dry matter and seed grain yield, respectively. The rate of root and shoot water loss due to salt stress exhibited significant negative correlation with shoot K⁺, but not with shoot Na⁺ and shoot K⁺/Na⁺ ratio. The genotypes showed a wide spectrum of response to salt stress across the growth stages; however, four genotypes, Altay2000, 14IWWYTIR‐19 and UZ‐11CWA‐8 (tolerant) and Bobur (sensitive), exhibited consistent responses to salinity across the three growth stages. The tolerant genotypes possessed better ability to maintain stable osmotic potential, low Na⁺ accumulation, higher shoot K⁺ concentrations, higher rates of PSII activity, maximal photochemical efficiency and lower non‐photochemical quenching (NPQ), resulting in the significantly higher dry matter production observed under salt stress. The identified genotypes could be used as parents in breeding for new varieties with improved salt tolerance as well as in further genetic studies to uncover the genetic mechanisms governing salt stress response in wheat.     

Maize genotypes with deep root systems tolerate salt stress better than those with shallow root systems during early growth

Maize (Zea mays L.) is susceptible to salinity but shows genotypic variation for salt tolerance. How maize genotypes with contrasting root morphological traits respond to salt stress remains unclear. This study assessed genotypic variation in salinity tolerance of 20 maize genotypes with contrasting root systems exposed to NaCl for 10 days (0, 50 mM or 100 mM NaCl, added in four increments every other day from 14 days after transplanting, DAT) in a semi-hydroponic phenotyping system in a temperature-controlled greenhouse. Considerable variation was observed for each of the 12 measured shoot and root traits among the 20 genotypes under NaCl treatments. Salt stress significantly decreased biomass production by up to 54% in shoots and 37% in roots compared with the non-saline control. The 20 genotypes were classified as salt-tolerant (8 genotypes), moderately tolerant (5) and salt-sensitive (7) genotypes based on the mean shoot dry weight ratio (the ratio of shoot dry weight at 100 mM NaCl and non-saline control) ± one standard error. The more salt-tolerant genotypes (such as Jindan52) had less reductions in growth, and lower shoot Na⁺ contents and higher shoot K⁺/Na⁺ ratios under salt stress. The declared salt tolerance was positively correlated with shoot height, shoot dry weight and primary root depth, and negatively correlated with shoot Na⁺ content at 100 mM NaCl. Primary root depth is critical for identifying salt responsiveness in maize plants and could be suggested as a selection criterion for screening salt tolerance of maize during early growth. The selected salt-tolerant genotypes have potentials for cultivation in saline soils and for developing high-yielding salt-tolerant maize hybrids in future breeding programmes.     

Maize Genotypes Differing in Salt Resistance Vary in Jasmonic Acid Accumulation During the First Phase of Salt Stress

Plant hormones are considered to play an important role in plant adaptation to drought and salt stress. The objective of the study was to investigate the changes in endogenous jasmonic acid (JA) in relation to differences in the salt resistance of maize genotypes. Two maize genotypes (SR 03 and Across 8023) were compared for changes in water relations, growth and tissue JA levels in response to 100 mm NaCl. Salt stress significantly reduced the shoot growth of both genotypes; however, SR 03 exhibited significantly less reduction in relative shoot fresh weight than Across 8023. Both genotypes showed an identical response to salt stress regarding plant water relations; therefore, genotypic differences in the salt resistance could not be attributed to changes in shoot turgor and these results were further confirmed by the response of both genotypes under equiosmotic stress (?0.49 MPa) of either 100 mm NaCl or PEG‐6000. GC‐MS/MS analysis showed that salt stress did not alter shoot JA levels of both genotypes, however significantly increased the root JA levels of Across 8023. In contrast, root JA levels of salt‐resistant SR 03 did not change by salt stress. Increase in root JA levels in response to stress treatments does not coincide with the growth inhibition of shoot in Across 8023. In contrast, both PEG and NaCl did not change the JA concentrations in both root and shoot tissues of SR 03. Growth assays with maize seedlings showed that JA supply in root medium inhibits shoot extension growth and both maize genotypes were sensitive to the inhibitory effects of JA. These results suggest that maize genotypes differ in JA accumulation during the first phase of salt stress and JA may indirectly be involved in leaf growth inhibition of the salt‐sensitive genotype. In addition, our results also showed that treatment of salt‐stressed plants with exogenous JA improved the Na⁺ exclusion by decreasing the Na⁺ uptake at the root surface.     

缺锌条件下小麦的养分吸收状况及不同基因型的耐性差异

采用螯合-缓冲营养液（Chelator-buffer culture solution）进行培养试验,对缺锌条件下3种小麦基因型（绵阳19、邯6172、新麦13）的生长发育状况及对P、Cu、Fe、Mn营养的影响进行了研究,并且应用4种指标,即锌效率（缺锌与锌充足供应条件下小麦地上部干物质之比）、相对冠根比（缺锌与锌充足供应条件下小麦冠根比之比）、缺锌条件下小麦地上部的锌吸收量、干物质量,对3种小麦的耐缺锌能力进行了比较。结果表明,在锌缺乏条件下小麦地上部生长量明显降低,而根系依然能保持相对较强的生长发育能力;不同小麦基因型对缺锌的耐性存在明显差异,其中邯6172的耐性最强;在缺锌胁迫条件下,小麦地上部Cu、Fe、Mn含量及Cu／Zn、Fe／Zn、Mn／Zn均明显升高,地上部锌含量与Cu、Fe、Mn含量均呈极显著负相关,说明锌缺乏能够促进Cu、Fe、Mn在地上部的累积。与此相反,锌缺乏条件下小麦P含量及吸收量均明显降低,地上部磷、锌含量之间极显著正相关,但与Cu,Fe,Mn相似,缺锌后P从根系向地上部的转运率升高。同时,对缺锌耐性最强的小麦基因型邯6172在锌缺乏条件下,地上部Cu、Fe、Mn含量的升高与P含量的降低幅度均是3种供试小麦中最大的,似乎表明小麦对锌缺乏的耐性大小与对Cu、Fe、Mn的吸收能力及与对P吸收的抑制有关。     

Morphological and physiological differences in the response of cereals to zinc deficiency

Greenhouse and growth chamber experiments were carried out using seven bread wheat (Triticum aestivum), three durum wheat (T. durum), two rye (Secale cereale), three barley (Hordeum vulgare), two triticale (x Triticosecale Wittmack) and one oat (Avena sativa) cultivars to study response to zinc (Zn) deficiency and Zn fertilisation in nutrient solution and in a severely Zn deficient calcareous soil. Visual Zn deficiency symptoms, such as whitish-brown necrotic patches on leaf blades, developed rapidly and severely in the durum wheat and oat cultivars. Bread wheat showed great genotypic differences in sensitivity to Zn deficiency. In triticale and rye, visual deficiency symptoms were either absent or appeared only slightly, while barley showed a moderate sensitivity. When grown in soil, average decreases in shoot dry matter production due to Zn deficiency were 15% for rye, 25% for triticale, 34% for barley, 42% for bread wheat, 63% for oat and 65% for durum wheat. Differential Zn efficiency among and within cereal species was better related to the total amount of Zn per shoot, but not to the Zn concentration in the shoot dry matter. However, in leaves of Zn efficient rye and bread wheat cultivars, the activity of Zn-containing superoxide dismutase was greater than in Zn inefficient bread and durum wheat cultivars, suggesting higher amounts of physiologically active Zn in leaf tissue of efficient genotypes. When grown in nutrient solution, there was a poor relationship between Zn efficiency and release rate of Zn-chelating phytosiderophores from roots, but uptake of labelled Zn (⁶⁵Zn) and its translocation to the shoot was higher in the Zn efficient rye and bread wheat cultivars than in inefficient bread and durum wheat cultivars. The results demonstrate that susceptibility of cereals to Zn deficiency decline in the order durum wheat > oat > bread wheat > barley > triticale > rye. The results also show that expression of high Zn efficiency in cereals was causally related to enhanced capability of genotypes to take up Zn from soils and use it efficiently in tissues. This revised version was published online in August 2006 with corrections to the Cover Date.     

Growth Properties and Ion Distribution in Different Tissues of Bread Wheat Genotypes (Triticum aestivum L.) Differing in Salt Tolerance

Four bread wheat genotypes differing in salt tolerance were selected to evaluate ion distribution and growth responses with increasing salinity. Salinity was applied when the leaf 4 was fully expanded. Sodium (Na⁺), potassium (K⁺) concentrations and K⁺/Na⁺ ratio in different tissues including root, leaf‐3 blade, flag leaf sheath and flag leaf blade at three salinity levels (0, 100 and 200 mm NaCl), and also the effects of salinity on growth rate, shoot biomass and grain yield were evaluated. Salt‐tolerant genotypes (Karchia‐65 and Roshan) showed higher growth rate, grain yield and shoot biomass than salt‐sensitive ones (Qods and Shiraz). Growth rate was reduced severely in the first period (1–10 days) after salt commencements. It seems after 20 days, the major effect of salinity on shoot biomass and grain yield was due to the osmotic effect of salt, not due to Na⁺‐specific effects within the plant. Grain yield loss in salt‐tolerant genotypes was due to the decline in grain size, but the grain yield loss in salt‐sensitive ones was due to decline in grain number. Salt‐tolerant genotypes sequestered higher amounts of Na⁺ concentration in root and flag leaf sheath and maintained lower Na⁺ concentration with higher K⁺/Na⁺ ratios in flag leaf blade. This ion partitioning may be contributing to the improved salt tolerance of genotypes.     

硼对绿豆植株生长发育及矿质营养状况的影响

在生长室利用水培研究了不同供硼水平对绿豆生长及矿质营养状况的影响。结果表明缺硼抑制绿豆生长，对根系的影响比对地上部的影响更大，表现在根冠比变小；供硼水平对植株的矿质营养含量也有明显的影响，缺硼降低了地上部和根系中的P，K，Fe的含量，促进Ca在根系中的积累，但地上部Ca的含量降低；缺硼时有利于Mg在植物体内的累积；硼对Mn的含量影响不大；严重缺硼时地上部Zn含量最高，但供硼正常时，Zn在根系中含量较高。     

磷胁迫下不同磷效率大豆某些性状的基因型差异

用液培法以4个不同磷效率的大豆基因型为材料,对其在缺磷胁迫条件下的主根长、根冠比、光合速率及抗衰老能力进行了研究。结果表明：耐低磷主要表现是刺激根的伸长,与磷低效基因型相比,磷高效基因型的主根长、根冠比增长比较明显;磷高效基因型的光合能力和生物膜的抗氧化能力都明显高于磷低效基因型。     

不同Zn2+活度对水稻根和叶生长生理特性的影响

在营养液水培条件下,研究了不同Zn2+活度((pZn2+9.7, pZn2+11.0和pZn2+> 11.5 )对水稻根叶的生长发育和若干生理特性的影响。结果表明：低Zn2+活度下,对水稻秧苗的出叶速度减慢,但不同基因型间存在明显差异,极度缺锌(pZn2+>11.5)时,敏感品种只生长3.5叶,而耐低锌品种生长4.5叶左右;轻度缺锌或缺锌初期叶绿素含量上升和     

Drought and heat stress reduce yield and alter carbon rhizodeposition of different wheat genotypes

Drought and high temperature are major environmental stress factors threatening wheat production during grain filling stage resulting in substantial yield losses. Four wheat genotypes (Suntop, IAW2013, Scout and 249) were planted under two temperature levels (25 and 30°C) and two water levels (15% and 25% soil moisture content). Wheat yield, leaf δ¹³C, plant rhizodeposition, shoot biomass and root traits were examined. Low moisture (drought stress) and high temperature (heat stress) decreased the grain yield of all wheat genotypes, in particular 249, while combined drought and temperature stresses had the most pronounced negative effect on plant biomass and grain yield. Decreasing soil water availability decreased the allocation of plant‐derived C to soil organic carbon (SOC) and to microbial biomass through rhizodeposition. Leaf δ¹³C decreased with increased yield, suggesting that higher yielding genotypes were less water stressed and allocated less C to SOC and microbial biomass through rhizodeposition. Wheat genotypes with lower root/shoot ratios and thinner roots were more efficient at assimilating C to the grain, while genotypes with higher root/shoot ratios and thicker roots allocated more C belowground through rhizodeposition at the expense of producing higher yield. Therefore, improving these traits for enhanced C allocation to wheat grain under variable environmental conditions needs to be considered.     

Genotypic variation in abscisic acid content,carbon isotope ratio and their relationship with cassava growth and yield under moisture stress and irrigation

This study was carried out to assess genotypic variability in abscisic acid content, carbon isotope ratio, and their relationship to storage root yield and yield components in cassava under irrigation and moisture stress. The study involved 20 cassava genotypes arranged in randomized complete block design with three replications. Irrigation water was applied using a drip irrigation system with a discharge rate of approximately 5.33 L m^-2 hr^-1. Significant (P < 0.05) genotypic variability was observed for all physiological, growth, and yield traits assessed. Abscisic acid content was higher under stress than irrigation and negatively correlated with root yield (r = -0.45), harvest index (r = -0.43), and above-ground biomass yield (r = -0.20) indicating that it can be used as indirect selection criteria against unproductive genotypes. Carbon isotope ratio was significantly and positively correlated with above-ground biomass yield (r = 0.20) but not root yield (r = 0.09). Estimates of genotypic variability indicated high values for most of the growth and yield components but low heritability values for abscisic acid content, carbon isotope ratio, stomatal conductance, and root yield under stress conditions. However, higher estimates were recorded under irrigation and in the combined analysis. It was also found from this study that carbon isotope ratio influences above-ground biomass but not storage root yield under stress conditions. The results from this study provide useful information on the relationship between abscisic acid content, carbon isotope discrimination, and storage root yield in field-grown cassava.     

Genetic variability in flooding tolerance of mungbean (Vigna radiata L. Wilczek) genotypes

The study was an exploratory in nature conducted using a large number of mungbean (Vigna radiata L. Wilczek) genotypes of diverse growth habit and adaptive characters. Soil flooding induced changes in eleven morpho-physiological characters of one-week old seedlings of 530 mungbean genotypes was compared in the study. The first and second principal components (PC) of principal component analysis (PCA) results accounted for 58 and 14%, respectively of the total variations of mungbean genotypes. The variation for first PC was composed mainly of relative dry weight (DW) of shoot and leaf as well as total DW. The second PC distinguished the genotypes that produced larger root system. There were seven clusters distinguished in the cluster analysis. The genotypes in cluster 4 and 6 performed better in respect of relative total DW and relative root DW, respectively and hence having flooding tolerance. The genotypes in clusters 7 and 1 performed very poorly and those of under clusters 3, 2 and 5 were moderate to poor. D² analysis indicated that the clusters differed significantly from each other. Discriminant function analysis (DFA) reaffirmed that more than 90% of the genotypes were correctly assigned to clusters. Both PCA and DFA confirmed that the relative total DW followed by shoot and leaf DW as well as leaf area were the major discriminatory variables and the root : shoot ratio and root DW were the secondary important variables to distinguish genotypes into groups. In this study, multivariate analyses were used in identifying the mungbean genotypes of desirable traits for flooding tolerance.     

Selection of wheat genotypes for biomass allocation to improve drought tolerance and carbon sequestration into soils

The biomass allocation pattern of plants to shoots and roots is a key in the cycle of elements such as carbon, water and nutrients with, for instance, the greatest allocations to roots fostering the transfer of atmospheric carbon to soils through photosynthesis. Several studies have investigated the root to shoot ratio (R:S) biomass of existing crops but variation within a crop species constitutes an important information gap for selecting genotypes aiming for increasing soil carbon stocks for climate change mitigation and food security. The objectives of this study were to evaluate agronomic performance and quantify biomass production and allocation between roots and shoots, in response to different soil water levels to select promising genotypes for breeding. Field and greenhouse experiments were carried out using 100 genotypes including wheat and Triticale under drought‐stressed and non‐stressed conditions. The experiments were set‐up using a 10 × 10 alpha lattice design with two replications under water stress and non‐stress conditions. The following phenotypic traits were collected: number of days to heading (DTH), number of productive tillers per plant (NPT), plant height (PH), days to maturity (DTM), spike length (SL), kernels per spike (KPS), thousand kernel weight (TKW), root biomass (RB), shoot biomass (SB), root to shoot ratio (R:S) and grain yield (GY). There was significant (p < 0.05) variation for grain yield and biomass production because of genotypic variation. The highest grain yield of 247.3 g/m² was recorded in the genotype LM52 and the least was in genotype Sossognon with 30 g/m². Shoot biomass ranged from 830 g/m² (genotype Arenza) to 437 g/m² (LM57), whilst root biomass ranged between 603 g/m² for Triticale and 140 g/m² for LM15 across testing sites and water regimes. Triticale also recorded the highest R:S of 1.2, whilst the least was 0.30 for wheat genotype LM18. Overall, drought stress reduced total biomass production by 35% and R:S by 14%. Genotypic variation existed for all measured traits useful for improving drought tolerance, whilst the calculated R:S values can improve accuracy in estimating C sequestration potential of wheat. Wheat genotypes LM26, LM47, BW140, LM70, LM48, BW152, LM75, BW162, LM71 and BW141 were selected for further development based on their high total biomass production, grain yield potential and genetic diversity under drought stress.     

Combined Effect of Zinc and Cadmium Levels on Root Antioxidative Responses in Three Different Zinc‐Efficient Wheat Genotypes

This work was undertaken to investigate the effect of zinc (Zn) nutrition on root antioxidative responses to cadmium (Cd) toxicity of three wheat genotypes differing in Zn efficiency. A hydroponic experiment was carried out in which two bread wheat genotypes (Triticum aestivum L. cvs. ‘Rushan’ and ‘Cross’) and one durum wheat genotype (Triticum durum L. cv. Durum) were exposed to three Zn²⁺ (10^?11.11, 10^?9.11 and 10^?8.81 μm ) and two Cd²⁺ (10^?11.21 and 10^?10.2 μm ) activity levels. ‘Durum’ showed the highest root sulfhydryl (‐SH) groups content and activity of catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) and the lowest root membrane permeability among the studied wheat genotypes. In ‘Durum’, Zn nutrition increased root ‐SH groups concentration of seedlings in Cd‐free nutrient solution. In ‘Cross’, as Zn²⁺ activity increased from 10^?11.11 to 10^?9.11 μm , root ‐SH groups concentration was increased while decreased with increasing Zn²⁺ to 10^?8.81 μm . Cadmium increased root membrane permeability at both 10^?11.11 and 10^?9.11 μm Zn²⁺ levels. Activity of CAT and APX increased in roots of ‘Durum’ plants exposed to Cd at Zn²⁺ = 10^?9.11 μm and thereafter decreased with increasing Zn²⁺ activity. In contrast, CAT and APX activity in roots of ‘Cross’ and ‘Rushan’ genotypes exposed to Cd decreased by increasing Zn activity to 10^?9.11 μm and then increased at Zn²⁺ = 10^?8.81μm . The results showed an increase in activities of antioxidative enzymes in Cd‐treated plants, although this increase was dependent on the crop genotype and Zn levels in the media.     

Inheritance of tolerance to zinc deficiency in barley

Barley (Hordeum vulgare L.) is often grown on alkaline zinc (Zn)‐deficient soils where reductions in yield and grain quality are frequently reported. Currently, the use of Zn‐based fertilizer along with Zn‐deficiency‐tolerant genotypes is considered the most thorough approach for cropping the Zn‐deficient soils; however, developing or breeding genotypes with higher Zn efficiency requires a good understanding of the inheritance of tolerance to Zn deficiency. This study was conducted to determine genetic control of this trait in barley. Two parental cultivars ('Skiff, moderately tolerant; and ‘Forrest’, sensitive), 185 F₂ plants, and 48 F₂‐derived F₃ families from this cross were screened to determine inheritance of tolerance to Zn deficiency using a visual score of deficiency symptoms. The segregation ratios observed indicated that greater tolerance to Zn deficiency in ‘Skiff compared with ‘Forrest’ at the seedling stage is controlled by a single gene with no dominance. The results also indicate that visual scores are useful for genetic analysis of tolerance to Zn deficiency.     

Germination characters and early seedling growth of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) genotypes under salt stress conditions

Screening of wheat genotypes as salt tolerance through seed germination and early seedling growth is crucial for their evaluation. Seeds of 20 wheat genotypes were germinated in Petri dishes on a sand bed irrigated with saline (15 dS m_-1) and control solutions for 10 days and also tested at different salinity levels (control, 4, 6, 8, and 10 dS m^-1) which were artificially developed in the soil for 30 days. At 10 days, germination percentage, rate of germination, co-efficient of germination, germination vigor index, shoot length, root length, and seedling dry weight were found to be affected due to salinity. Salt tolerance index (STI) for seedling dry weight maintained a significant positive correlation with rate of germination, germination vigor index, shoot length, and root length, which indicates that these parameters could be used as selection criteria for screening wheat genotypes against salt stress. Significant differences in shoot length, root length, and seedling dry weight in 30-day-old seedlings were observed among selected wheat genotypes as well. From the overall observation of germination characters and early seedling growth, it was concluded that the wheat genotypes including Gourab, Shatabdi, Bijoy, Prodip, BARI Gom 26, BAW 1186, and BAW 1189 showed better salt tolerance as compared to others.