Physiological and Biochemical Responses of Hexaploid and Tetraploid Wheat to Drought Stress

An experiment was conducted to investigate the physiological and biochemical responses of two hexaploids viz., C 306 (water stress tolerant) and Hira (water stress susceptible), and two tetraploids, HW 24 (Triticum dicoccum) and A 9‐30‐1 (Triticum durum) wheat genotypes to water stress under pot culture condition. Water stress was imposed for a uniform period of 10 days at 50, 60 and 70 days after sowing (DAS) and observations were recorded at 60, 70 and 80 DAS. Total dry matter and plant height were recorded at harvest. Water stress caused a decline in relative water content (RWC), chlorophyll and carotenoid content, membrane stability and nitrate reductase activity and increased accumulation of proline at all stages and abscisic acid (ABA) at 80 DAS in all the genotypes. Both the tetraploids showed a lower reduction in RWC and highest ABA accumulation under water stress. Among the hexaploids Hira showed the most decline in RWC and the lowest ABA accumulation. The tetraploids also showed comparatively higher carotenoid content and membrane stability, closely followed by C 306, while Hira showed the minimum response under water stress. Nitrate reductase activity and chlorophyll content under irrigated conditions were highest in Hira but under water stress the lowest per cent decline was observed in C 306, followed by HW 24, A 9‐30‐1, and Hira. Proline accumulation under water stress conditions was highest in hexaploids C 306 and Hira and lowest in tetraploids HW 24 and A 9‐30‐1. Tetraploids HW 24, followed by A 9‐30‐1 maintained higher plant height and total dry matter (TDM) under water stress and also showed a lower per cent decline under stress than hexaploids C 306 and Hira. From the results it is clear that proline accumulation did not contribute to better drought tolerance of tetraploids than hexaploids. It is also apparent that water stress tolerance is the result of the cumulative action of various physiological processes, and all the parameters/processes may not be positively associated with the drought tolerance of a particular tolerant genotype.     

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.     

Ethyloxanilates as specific male gametocides for wheat (Triticum aestivum L.)

Induction of male sterility by deployment of male gametocides holds immense potential in heterosis breeding of wheat. The efficacy of a new class of male gametocide for wheat (Triticum aestivum L.) is described: ethyloxanilates, the most active example of this class being ethyl 4‐fluorooxanilate (E4FO). E4FO induces male sterility, specifically, without detectable effects on various agronomic features and female fertility. The plants sprayed once with 0.15% E4FO exhibited 100% pollen and floret sterility without causing a significant reduction in total yield. E4FO was screened on 29 genotypes of wheat at 0.15% test concentration and was observed to induce 99.76 ± 0.37% male sterility. Thirteen F₁‐hybrids of wheat were produced using the gametocide in Winter 2000–2001 and were evaluated for their agronomic performance in Winter 2001–2002. The cross combinations viz., lines WR 544 × HW 2046 and HW 2044 × WR 956 have outperformed their respective better parents by 48.17% and 23.42% in grain yield/plant and thus have potential as hybrids.     

A new phenotyping technique for screening for drought tolerance in lentil (Lens culinaris Medik.)

Screening for drought tolerance is severely handicapped by the lack of a simple and reliable phenotyping technique. The objective of this study was to develop a new screening technique based on seedling survivability, drought tolerance score, root and shoot length, and fresh and dry weight of roots and shoots of lentil plants exposed to drought under hydroponic conditions. Its effectiveness was compared with two soil culture techniques. The hydroponic technique involved removing 15‐day‐old seedlings of 80 genotypes from the nutrient solution and exposing them to air for 5 h daily for 6 days. Three genotypes received from ICARDA, ‘ILL‐10700’, ‘ILL ‐ 10823’ and ‘FLIP‐96‐51’, showed maximum seedling survivability and minimum reduction in the growth parameters with a drought score of 0.0–0.2 indicating higher tolerance to drought stress, while Indian genotypes ‘JL‐3’, ‘E‐153’ and ‘VL‐507’ showed no seedling survivability and maximum reduction in growth parameters with a drought score of 4.0 indicating low drought tolerance. The results suggest that this new phenotyping technique is effective, rapid and easy for screening a large number of genotypes.     

Comparison of a modified assay method for the endopeptidase marker Ep-D1b with the Sequence Tag Site marker XustSSR2001–7DL for strawbreaker foot rot resistance in wheat

The endopeptidase marker Ep‐D1b and Sequence Tag Site (STS) marker XustSSR2001–7DL were reported to be closely associated with the most effective resistance gene (Pch1) in wheat (Triticum aestivum L.) for strawbreaker foot rot [Pseudocercosporella herpotrichoides (Fron) Deighton]. Our objectives were to: (i) develop an efficient assay method for Ep‐D1b in wheat; (ii) correlate endopeptidase zymograms to strawbreaker foot rot reactions of various wheat genotypes; and (iii) compare the utility of Ep‐D1b and XustSSR2001–7DL for predicting disease response. An improved method of assaying for the Ep‐D1b marker using roots from a single seedling was developed, which is a 2.5‐fold improvement over the previous method. Thirty‐eight wheat genotypes with known reactions to strawbreaker foot rot were analysed for Ep‐D1b and the STS marker. Six distinct endopeptidase zymograms were identified among these 38 genotypes tested, and three of these patterns were novel. The endopeptidase marker was 100% accurate for predicting strawbreaker foot rot disease response, whereas the STS marker predicted the correct phenotype with approximately 90% accuracy. The endopeptidase marker Ep‐D1b was more effective and was more economical for use in marker‐assisted selection strategies for Pch1 in our laboratory compared with the STS marker.     

Genetic variation in drought tolerance at seedling stage and grain yield in low rainfall environments in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Genetic architecture of seedling drought tolerance is complex and needs to be better understood. To address this challenge, we developed a protocol to identify the most promising drought-tolerant genotypes at the seedling stage in winter wheat. A population of 146 recombinant inbred lines (F₉) derived from a cross between wheat cultivars, ‘Harry’ (seedling drought tolerant) and ‘Wesley’ (seedling drought susceptible) were used in this study. All genotypes were sown in three replications in a randomized complete block design under controlled conditions in a greenhouse. Seven traits were scored and grouped into tolerance traits; days to wilting, leaf wilting, and stay green and survival traits; days to regrowth, regrowth, drought survival rate, and recovery after irrigation. Three selection indices were calculated (1) tolerance index, (2) survival index, and (3) drought tolerance index (DTI). The same set of genotypes were also tested for grain yield in two low rainfall environments for two seasons. High genetic variation was found among all genotypes for all seedling traits scored in this study. Correlations between tolerance and survival traits were weak or did not exist. Heritability estimates ranged from 0.53 to 0.88. DTI had significant phenotypic and genotypic correlations with all seedling traits. Genotypes were identified with a high drought tolerance at the seedling stage combined with high grain yield in low rainfall. Breeding for tolerance and survival traits should be taken into account for improving winter wheat drought tolerance at seedling stage. The selected genotypes can be used for to further improve drought tolerance in high yielding wheat for Nebraska.     

Genes for wheat stem rust resistance postulated in German cultivars and their efficacy in seedling and adult‐plant field tests

Stem rust of wheat (caused by Puccinia graminis f.sp. tritici) gained high international attention in the last two decades, but does not occur regularly in Germany. Motivated by a regional epidemic in 2013, we analysed 15 spring and 82 winter wheat cultivars registered in Germany for their resistance to stem rust at the seedling stage and tested 79 of these winter wheat cultivars at the adult‐plant stage. A total of five seedling stem rust resistance genes were postulated: Sr38 occurred most frequently (n = 29), followed by Sr31 (n = 11) and Sr24 (n = 8). Sr7a and Sr8a occurred only in two spring wheat genotypes each. Four cultivars had effective seedling resistance to all races evaluated that could only be explained by postulating additional resistance genes (‘Hyland’, ‘Pilgrim PZO’, ‘Tybalt’) or unidentified gene(s) (‘Memory’). The three winter wheat cultivars (‘Hyland’ ‘Memory’ and ‘Pilgrim PZO’) were also highly resistant at the adult‐plant stage; ‘Tybalt’ was not tested. Resistance genes Sr24 and Sr31 highly protected winter wheat cultivars from stem rust at the adult‐plant stage in the field. Disease responses of cultivars carrying Sr38 varied. Mean field stem rust severity of cultivars without postulated seedling resistance genes ranged from 2.71% to 41.51%, nine of which were significantly less diseased than the most susceptible cultivar. This suggests adult‐plant resistance to stem rust may be present in German wheat cultivars.     

苗期调控对晚播小麦产量及氮素利用的影响

针对冬小麦因播期推迟造成产量损失的问题,以2个不同分蘖能力的冬小麦品种中麦8号和航麦501为供试材料,研究苗期覆膜和补施氮肥对晚播小麦产量及氮素利用的影响。试验设置3个播期：10月5日适期播种（S0,对照）、10月15日适当晚播（S1）和10月25日过晚播（S2）。结果表明：随着播期推迟,小麦产量逐渐降低。晚播条件下,苗期覆膜和补施氮肥可调控冬小麦产量构成因素、农艺性状、茎蘖生长、成穗率以及氮素的吸收利用。综合而言,晚播条件下,覆膜和补施氮肥有利于提高小麦穗长、总小穗数及冬前群体数量;同时,覆膜可显著提高2个品种晚播条件下的分蘖成穗率和过晚播条件下的植株氮素积累量（PNA）及氮肥偏生产力（PFP）,增幅分别为46.4%~89.1%、12.7%~26.5%和19.5%~20.1%;补施氮肥在过晚播条件下有利于成穗率的提高,增幅为18.5%~34.7%。2种调控措施均有利于增加晚播小麦产量,增幅达1.4%~19.5%。但不同分蘖力的小麦对2种调控措施的响应存在差异。综合考虑产量及氮素利用等各方面因素,在晚播条件下,相比于补施氮肥,苗期覆膜更有利于提高晚播小麦产量,弥补晚播造成的产量损失,但在实际操作和节约生产成本方面,前者优于后者。     

Leaf shape × sowing density interaction affects chickpea grain yield

Modifying plant architecture is considered a promising breeding option to enhance crop productivity. Modern chickpea (Cicer arietinum L.) cultivars with either compound (wild‐type) or simple leaf shapes are commercially grown but the relationships between leaf shape and yield are not well understood. In this study, a random sample of ‘Kabuli’ type progeny lines of both leaf types, derived from two crosses between modern American simple leaf cultivars and early‐flowering wild‐type breeding lines, were planted at different sowing densities. Leaf area development and final grain yield in genotypes of the two leaf types responded differently to changes in sowing densities. Compound leaf lines attained higher leaf area indices and higher grain yields at both low and high sowing densities. Yield responses of the simple leaf lines to increasing sowing density were significantly higher compared to compound leaf genotypes in two of three field experiments. The prospects for utilizing the simple leaf trait as a breeding target for short‐season growing areas are discussed.     

陇东半干旱地区冬季积温变化特征及对冬小麦的响应

为了解陇东半干旱地区环县冬季积温变化特征及其对冬小麦的影响,通过Mann-Kendell统计检验法、Pearson相关分析法等手段对冬季积温以及冬小麦发育期资料进行分析研究。结果表明：（1）冬季积温在近36年的变化过程中呈现出逐年上升趋势;Mann-Kendall突变检验发现,1990年为冬季积温突变的年份;Morlet小波变换分析得到在30~35年上冬季积温呈现出最为显著的周期变化规律;（2）通过对冬小麦发育期特征分析,发现冬小麦除了在分蘖期表现为推迟的状况,其他播种、出苗、三叶、越冬等发育期均表现为提前的变化特征;对冬小麦发育期与积温进行相关分析,相关系数均为负相关,表明大多数发育期提前1~5天;在冬季积温偏高的年份,冬小麦各发育期普遍提前4~14天;（3）对冬小麦物候间隔期的特征进行分析发现：冬小麦在播种—出苗、播种—分蘖、播种—越冬、播种—返青以及播种—抽穗期,间隔时间呈现出延长的变化特征;在播种—三叶、播种—起身、播种—拔节、播种—开花、播种—成熟期,间隔时间呈现出缩短的变化特征。     

播种深度和播后淹水时间对冬小麦出苗率及冬前幼苗质量的影响

为探讨淹水时间和播种深度对不同小麦品种出苗率及冬前幼苗健壮程度的影响,在控制条件下对四个不同类型品种进行了研究,结果表明：播种后淹水1-4天,可导致五种播深TN18的平均出苗率降低22.43%,越冬期单株干物重降低21.56%;JM20分别降低23.43%和18.46%;SN8355分别降低9.66%和19.86%;LM14分别降低6.21%和23.20;说明淹水对TN18 JM20两品种出苗率的影响显著低于SN8355和LM14。淹水可使3cm地温降低0.470C,5cm降低1.150C。在淹水时间相等条件下,随播种深度的增加,对出苗率和幼苗质量的影响逐渐增大;在播深相同时,淹水时间越长影响越大。在播深2cm～6cm范围内,播种越浅出苗率和越冬期单株干物重越高,淹水对其的影响也越小,浅播是降低渍涝地区渍涝灾害的有效措施;但由于浅播分蘖节基本处在2cm处,不利于抗寒和抗旱,因而该结果仅适于渍涝麦田应用。     

稻秸还田下耕作与播种方式对小麦出苗及产量的影响

为了研究稻秸还田下耕作与播种方式对小麦出苗及产量的影响,通过大区试验,分析了稻秸全量还田下不同耕作与播种方式对小麦出苗率、出苗均匀性及产量性状的影响。结果显示,相同的播种方式下,浅耕处理小麦出苗率高于免耕处理,但出苗均匀性差于后者;相同的耕作方式下,播种方式对小麦出苗率和出苗均匀性的影响差异较大,其中,机械匀播方式下小麦出苗率最高,出苗均匀性最好;小麦出苗率和出苗均匀性通过影响穗数、穗粒数、千粒重而影响籽粒产量,同一耕作方式下机械匀播小麦籽粒产量均高于其余2种播种方式,免耕和浅耕下机械匀播小麦产量分别达6484.35 kg/hm~2和6476.20 kg/hm~2。因此,稻秸全量还田条件下,建议采用免耕机械匀播方式,能有效改善小麦田间出苗情况,进而获得较高的籽粒产量。     

Plant regeneration through callus initiation from mature embryo of Triticum

The behaviour of diverse Triticum genotypes in the tissue culture response of mature embryo callus was compared, and factors affecting tissue culture response were studied in this paper. Significant differences were detected in callus induction, embryogenic callus differentiation, plantlet regeneration and culture efficiency when mature embryos of 31 plants of different Triticum species were compared. These were the main wheat cultivars of the Chinese northern winter‐type wheat region and breeding lines (Triticum aestivum L.), durum wheat (Triticum durum Desf.), cultivable emmer wheat (Triticumdicoccum Schuble) and the common wheat progenitors Triticum dicoccoides and Triticum aegilopides. The genotype dependency was particularly high in tissue culture of mature embryos of these Triticum genotypes. The efficiency of induction, differentiation and regeneration of mature embryos callus was high in genotypes selected out. Mature embryo‐derived callus of HB341, TS021, SN2618, T. dicoccum, HB188, and T9817 showed better tissue culture response than the other genotypes. Plantlets can be regenerated from mature embryo‐derived callus of 31 genotypes, saving on growth facility resources and time required for the collection of other explants, and providing a solid basis for the genetic transformation and molecular plant breeding of Triticum plants.     

Genotypic and temperature effects on wheat grain yield and quality in a hot irrigated environment

High temperature influences both grain yield and end‐use quality of wheat. The objectives of this study were to evaluate the performance of selected wheat genotypes under heat stress and to examine the effects of high temperatures during grain filling on grain yield and end‐use quality parameters. Fifteen bread wheat genotypes in 2000/2001 and 18 genotypes in 2002/2003 were evaluated under the optimum and late‐sowing conditions of the irrigated hot environment of the Gezira Research Farm, Wad Medani, Sudan. The genotypes comprised released varieties and elite lines from the Sudanese wheat improvement programme. Data collected included grain yield, grain weight and grain end‐use quality including protein content, protein composition, SDS sedimentation values (SDSS) and gluten strength as determined by mixograph analyses. High temperatures significantly decreased grain yield by decreasing grain weight. Although genotypes exhibited variation in magnitude of response, results indicated that high temperature during grain filling increased both soluble and insoluble protein contents, SDSS, mixograph peak height (MPH) and the descending slope at 2 min past peak (MDS). In contrast, mixograph peak time (MPT) and the curve width at 2 min past peak (MCW) were significantly decreased. Flour protein correlated positively with SDSS, MPH and MDS and negatively with MCW. MPT correlated negatively with MDS and positively with MCW. Results indicate that high temperature increased both soluble and insoluble protein contents, SDSS and MPH, and hence the gluten strength, but decreased flour mixing time and tolerance and hence the dough elasticity. Variation observed among genotypes suggests that grain end‐use quality could be improved under high temperature conditions utilizing the available variability; however, it might require evaluation under various growing conditions.     

Genetic analysis of apical lethality in <Emphasis Type="Italic">Triticum aestivum</Emphasis> L.

Investigations were carried out to determine the nature and number of genes governing apical lethality (apical death) in a number of intervarietal crosses of wheat. Genetic analysis of data in segregating generations of the cross WR95/HW2041 and its reciprocal cross revealed that WR95 carries a recessive gene that leads to the death of certain individuals when combined with another recessive gene derived from HW2041. The phenomenon, which is denoted here as “apical lethality”, is controlled by two complementary recessive genes coming together from two different parents in certain F₂ individuals. The gene symbols apd ₁ in WR95 and apd ₂ in HW2041 are proposed for these genes of apical lethality, respectively. Uniculms observed in the F₂ generation are heterozygous (apd ₁ apd ₁ Apd ₂ apd ₂) and, therefore, the uniculmness trait does not breed true. Of the wheat genotypes tested, the gene apd ₂ was found to be present in CL983, CL1019, Lok-1, HW2041, HD2329, HW2011, WH147, HW2042, HW2047, WR196, WR544, WR798 and WR936, while the remaining genotypes, including some of the exotics such as Atila, carried both Apd ₁ and Apd ₂ in the homozygous condition.     

Virtual modeling based on deep phenotyping provides complementary data to field experiments to predict plant emergence in oilseed rape genotypes

Breeding oilseed rape for oil and protein contents may have led to differences in seedling emergence in genotypes. New opportunities for deep automated phenotyping of germination and seedling growth are being developed on phenotyping platforms. Our aim was to demonstrate that using these data to parameterize a crop emergence model complements field experiments for the evaluation of differences among genotypes. Five genotypes, chosen in a diverse set of winter oilseed rape for their different germination speeds, were phenotyped for germination at different temperatures and water potentials as well as for radicle and hypocotyl growth. These data were used as parameters to run the SIMPLE crop emergence model over a period of 27 years (1985–2012), at two locations, one in France and one in Germany, and at four sowing dates. Field experiments were performed in 2012, 2013 and 2014, and the emergence of the five genotypes was measured at early and late sowing dates. First, model predictions were compared with observed field emergence in the French sowing trials in 2014. The model proved to be rather good at predicting the emergence of the genotypes. Then, for the simulation study, the model extended the observed differences between locations and sowing dates over a greater number of years. The model also identified the main reasons for non-emerging seedlings and their frequencies in the simulated sowings. Differences between the five genotypes were on average very small, but complex interactions appeared that led to bigger differences under certain sowing conditions. This study demonstrates that combining deep phenotyping with crop models in simulation studies paves the way for more precise and detailed evaluation of genotypes.     

基肥施用方式对小麦出苗及苗期生长的影响

通过室内盆栽试验研究不同基肥施用方式对小麦出苗及苗期生长的影响。设置种肥混播条播、条播侧方施肥、条播下方施肥、种肥混播宽幅撒播4种播种施肥方式,同时每个播种施肥方式下设置225、375、600 kg/hm² 3个肥料用量水平。结果表明,种肥混播条播方式对小麦的出苗影响极为明显,且随着施肥量的增加小麦出苗率明显降低,条播侧方施肥、下方施肥以及种肥混播宽幅撒播方式对于小麦的出苗率影响不大。在种肥混播方式下,无论条播还是宽幅撒播方式均表现出了随着施肥量增加小麦株高和根系增加的趋势,其中种肥混播宽幅撒播方式下小麦株高和根长数值相对较高。同一播种施肥方式下,小麦地上部生物量随着施肥量的增加而增加,而在等量肥料投入的情况下,地上部生物量均表现为种肥混播宽幅撒播>条播侧方施肥>条播下方施肥>种肥混播条播。本试验条件下,建议小麦基肥采用种肥混播宽幅撒播的方式,以降低化肥用量、保证出苗安全和培育壮苗。     

Influence of Soil Temperature on Seedling Emergence and Early Growth of Peanut Cultivars in Field Conditions

Peanut or groundnut (Arachis hypogaea L.) sown in early spring often has poor seed germination and seedling development. The influence of soil temperature on seedling emergence and early growth of six peanut cultivars (Florida MDR98, Southern Runner, Georgia Green, SunOleic 97R, Florunner and C‐99R) was studied in natural field soil profiles in temperature‐gradient greenhouses. We evaluated the influence of a range of soil temperatures by sowing at eight dates between January 2001 and May 2002 in Gainesville, Florida. On each sowing date, two additional temperature treatments (ambient and ambient +4.5 °C air temperature) were evaluated by sowing on either end of each greenhouse and applying differential heating. In total, 16 different soil temperature treatments were evaluated. Each treatment was replicated four times in four different greenhouses. Mean soil temperature from sowing to final emergence in different treatments ranged from 15 to 32 °C. Sowing date, temperature treatment and cultivar had significant effect on seedling emergence and development (V₂ stage). For all cultivars, the lowest germination was observed at the earliest sowing date (coolest soil temperature). Among cultivars, Florida MDR98 was the most sensitive to reduced (cool) temperature with the lowest germination and smallest seedling size at 21 days after sowing, followed by Southern Runner. Georgia Green was the most cold‐tolerant with the highest germination, followed by SunOleic 97R. There were no significant differences among cultivars for base temperature, which averaged 11.7 and 9.8 °C for rate of emergence and rate of development to V₂ stage respectively. These results imply that cultivar choice and/or genetic improvement of peanut for cold tolerance during emergence and seedling development in regions where cooler soil temperatures persist and/or regions where early sowing is desirable.     

Waterlogging tolerance of pea at germination

Peas (Pisum sativum L.) are exposed to waterlogging at germination when grown as relay in rice‐based cropping. Ninety‐one germplasm accessions were evaluated in relay (sown in waterlogged soil), and subsequently 10 diverse genotypes compared under relay and sole cropping (conventional tillage sowing) over two seasons in Bangladesh. Contrasting genotypes, BM‐3, NL‐2 and Kaspa, were further evaluated in three waterlogging treatments (drained control, 4 and 8 days waterlogging) in the glasshouse. Conspicuous variation in waterlogging tolerance at germination was observed in the field and confirmed under controlled conditions. In relay sowing in 2011, emergence of a few genotypes was affected by waterlogging. In 2012, emergence in relay was severely affected (12 plants/m²) compared to sole sowing (37 plants/m²). Among genotypes BM‐3 had 6 plants/m² emerge, which all subsequently died, in contrast to NL‐2 in which emergence was 13 plants/m² with all plants surviving. In the glasshouse, there was 14% emergence in BM‐3, 40% in NL‐2 and 55% in Kaspa after 8 days of waterlogging. Such marked differences in waterlogging tolerance at germination in the model pea are the first reported and illustrate prospects for selection to improve adaptation to relay sowing in South Asia.     

Regeneration of fertile doubled haploid plants from colchicine-supplemented media in wheat anther culture

The effect of colchicine added to induction medium for the production of fertile doubled haploid plants after in‐vitro anther culture was studied in wheat, Triticum aestivum L. For this, one winter and two spring wheat varieties were used. Anther cultures of the three genotypes were treated with 0.03% colchicine for 3 days at the beginning of microspore induction. Colchicine had no significant effect on anther response and embryoid production of the genotypes examined. However, in the winter wheat genotype ‘Mv Szigma’, colchicine caused a significant reduction in microspore‐derived structures. A significant decrease was also observed in plant regeneration ability of two genotypes (‘Vergina’ and ‘Acheloos’) after colchicine treatment. In addition, a significant reduction of the albinos produced was observed in all genotypes after olchicine treatment. In contrast, the regenerants obtained from the colchicine‐supplemented induction media produced significantly higher percentages of fertile plants in all genotypes. However, the level of fertility, was significantly different among the fertile plants obtained. This, together with the observation that in the case of the winter wheat variety the colchicine treatment resulted in 100% completely fertile plants with a high seed‐setting ability indicate that there is space for further improvement of the method when it is applied to spring cultivars. Finally, the increased number of seeds per 100 plated anthers obtained from all three genotypes after colchicine treatment, clearly demonstrates that the addition of colchicine to induction medium was superior to the conventional anther culture method and it could therefore be introduced into wheat breeding programmes.