Spike Yield Research Articles

Integrated use of NPK fertilizer with FYM influences growth, floral attributes, soil fertility and nutrient uptake of gladiolus in an Inceptisol of semi-arid tropics

Various combinations of farmyard manure (FYM), nitrogen (N), phosphorous (P) and potassium (K) wereevaluated to optimize their levels for growth, yield and nutrient uptake of Gladiolus hybridus Hort. cv. Trader Horn grown under open field conditions. The field trials were conducted during two cropping seasons (2013–14 & 2014–15) in a randomized block design with three replications. The treatments consisted of three levelsof FYM (0, 5 and 10 t ha−1); four levels, each of N (0, 100, 200 and 300 kg ha−1), P and K (0, 40, 80 and 120 kg ha−1), respectively. The results showed substantial improvement in morphological and floral characteristics ofgladiolus with increasing levels of FYM and NPK dosage. The nutrient consortium, FYM 10 t ha−1 and 300, 120 and 120 kg NPK ha−1 (T1) were found to be most effective in enhancing plant height (142.0 cm), number of leaves(8.9), spike length (115.1 cm), rachis length (72.0 cm), florets per spike (17.4) and spike yield m−2 (19.1). Theseexperiments also showed that balanced application of N, P and K significantly promoted the soil fertility andplant nutrient uptake.

Relationship Among Yield and Yield Components of Winter Wheat (Triticum aestivum L.) Cultivars, as Affected by Tillage Systems

The relationships among grain yield and yield components of 6 winter wheat cultivars in Romania, as affected by two contrasting tillage systems (no tillage-NT and chisel tillage-CT) were studied during five growing seasons (2011/12-2015/16) at Fundulea, which is located in the middle of Eastern Romanian Danube Plain. In order to determine the relationship between the investigated traits, both correlation method and linear regression were used on the level of significance 5%, 1% and 0.1%, dependant variables being considered as already late formed features in ontogenesis. Under both NT and CT tillage systems, mean positive correlations between number of kernels per spike and individual kernel weight per spike (r=0.783***and r=0.524**, respectively) and strong positive correlations between grain yield and number of spikes mˉ² (r=0.893*** and r=0.905***, respectively) were established. Weak correlation between kernel weight per spike and thousand kernel weight (r=0.379* and r=0.456*, respectively) was also established. Due to lower nutrients availability in NT system versus CT system, one can ascertain a significant diminution of number of grains per spike and grain weight per spike together with spike density increasing. Under CT system versus NT system, the significant TKW diminution due to increasing of number of grains per spike could be attributed to the diminution of soil moisture preservation as follows of crop residue incorporation.

Morphological Characterization for Identification of Drought Adapted Genotypes in Wheat (Triticum aestivum L.) under Drought Stress

Drought is one of the major limitations to wheat production worldwide. This study was designed to identify the drought adapted genotypes among 160 wheat genotypes. Five morphological traits namely leaf morphology, leaf angle, leaf rolling, waxiness on leaf, spike fertility and nine yield traits namely days to heading, days to anthesis, days to maturity, grain filling duration, spikelets per spike, grains per spike, grain weight per spike (g), 1000grain weight (g), and grain yield per plant (g). Grain yield per plant exhibited highly significant and positive correlation with 1000-grain weight, grain weight per spike, waxiness score, indicating dependency of yield on these traits. Based on path analysis, maximum positive direct effect on grain yield per plant was contributed mostly by days to maturity, followed by 1000 grain weight, waxiness score, number of grains per spike, grain weight per spike and leaf rolling score. From our results, waxiness score and leaf rolling score showed strong association with grain yield per plant. We have selected 18 genotypes based on high morphological score aswell-as high grain yield per plant namely; DBW50, HD2985, HD3043, HD2687, HD3059, HD3076, HD3093, HI1531, HW1105, PBN142, PBW502, WH1080, WH730, AUS30354, AUS30518, DRYSDALE, SB187, SSRT17. These genotypes can be utilized in drought breeding programme for development of mapping population, as well as drought resilience varieties for rainfed areas.

Variability of Number of Spikes per Unit Area and Grain Yield Effected by Different Sowing Densities оf Winter Wheat (Triticum aestivum L.)

The sowing density of wheat is important for expression of number of spikes per unit area, grain yield as well as other yield components. The aim of this work is investigation of variability of grain yield and number of spikes per unit area influenced by different sowing densities under different environmental conditions. Three wheat genotypes NS 40, Prima and Nova Bosanka were studied at seven different sowing densities (384, 424, 451, 504, 544, 588 and 604 seeds m-2) with four replications on experimental plot of one m2 on field experiment in agro‒ecological conditions of Banja Luka during two successive growing seasons. In all studied wheat cultivars, the lowest number of spikes m-2 and the lowest grain yield were found on variant of lowest sowing density (384 seeds m-2), while the highest number of spikes m-2 and the highest grain yield were found on variant of 588 seeds m-2 in both years. The wheat genotype NS 40S had the highest number of spikes m-2, while Nova Bosanka had the lowest at all variants of sowing densities in both years. Mainly, at all variants of sowing densities, the highest values of analyzed traits were expressed in first year of experimental investigation. Depending of year and variant of sowing density the highest grain yield were found in NS 40 and Prima, while the lowest grain yield had Nova Bosanka in both years of experiment. In general, the recommended wheat sowing rates should be confirmed in the specific area of production and for the specific genotype.

A novel allele of TaGW2-A1 is located in a finely mapped QTL that increases grain weight but decreases grain number in wheat (Triticum aestivum L.)

Key messageA novel TaGW2-A1 allele was identified from a stable, robust QTL region, which is pleiotropic for thousand grain weight, grain number per spike, and grain morphometric parameters in wheat.Thousand grain weight (TGW) and grain number per spike (GNS) are two crucial determinants of wheat spike yield, and genetic dissection of their relationships can help to fine-tune these two components and maximize grain yield. By evaluating 191 recombinant inbred lines in 11 field trials, we identified five genomic regions on chromosomes 1B, 3A, 3B, 5B, or 7A that solely influenced either TGW or GNS, and a further region on chromosome 6A that concurrently affected TGW and GNS. The QTL of interest on chromosome 6A, which was flanked by wsnp_BE490604A_Ta_2_1 and wsnp_RFL_Contig1340_448996 and designated as QTgw/Gns.cau-6A, was finely mapped to a genetic interval shorter than 0.538 cM using near isogenic lines (NILs). The elite NILs of QTgw/Gns.cau-6A increased TGW by 8.33%, but decreased GNS by 3.05% in six field trials. Grain Weight 2 (TaGW2-A1), a well-characterized gene that negatively regulates TGW and grain width in wheat, was located within the finely mapped interval of QTgw/Gns.cau-6A. A novel and rare TaGW2-A1 allele with a 114-bp deletion in the 5′ flanking region was identified in the parent with higher TGW, and it reduced TaGW2-A1 promoter activity and expression. In conclusion, these results expand our knowledge of the genetic and molecular basis of TGW-GNS trade-offs in wheat. The QTLs and the novel TaGW2-A1 allele are likely useful for the development of cultivars with higher TGW and/or higher GNS.

Effect of planting time and spacing on growth, flowering and spike yield of gladiolus

An investigation was conducted at the Horticulture Research Farm, Babasaheb Bhimrao Ambedkar University (A Central University), Vidya-vihar, Rae Bareli Road, Lucknow - 226025 (U.P.) to study the impact of spacing and time of planting on growth, flowering and corm production of gladiolus (Gladiolus grandifloras L. 'Aldebaran'). The experiment consisted of 16 treatments laid out in factorial randomized block design with three replications. Corms were sown in different times (November 5, 15, 25 and December 5) and different spacing at 20×30, 20×20, 30×30, 30×40 cm spacing. The study showed that better improvement in vegetative growth and floral characters was observed in treatment S2D1 i.e., when the gladiolus corms are planted on November 15 and at 30×30 cm spacing. It was also observed that corm and cormels weight, number of corm and cormels were significantly varied in spacing and time of planting and it was best under S2D1 i.e., 30×30 cm spacing and November 15 planting. It is concluded that gladiolus corm ('Aldebaran') planted on November 15 (D1) and at 30×30 cm spacing (S2) performed better and showed higher corm production as well as good flower characteristics under Lucknow condition.

Selection of castor germplasm with important traits for drought tolerance under field conditions

India is the leading producer of castor with major area under rainfed cultivation. To improve the productivity in rainfed areas, varieties and hybrids with drought tolerance and water use efficiency (WUE) have to be developed. Hence, it is essential to select germplasm with important traits viz: for root growth, WUE, drought tolerance etc. Fourteen castor genotypes with more root volume (225–557 cm3), root dry weight (38–122 g/pl) and one poor root check (root volume of 94 cm3, root dry weight of 15.2 g/pl.) identified by screening in root structures were sown in field for 2 years. The experiment was conducted during 2010–2012 in late rabi (November first week) in split plot design with three replications and water stress was imposed from 30 to 90 DAS by withholding irrigation. Results revealed severe growth reduction in terms of reduced plant height, leaf number, stem girth, branches and total dry matter (56% reduction) with water stress. Seed yield of primary spike reduced significantly with water stress, but the reduction was less pronounced in secondaries and compensated in later order spikes. The reduction in total seed yield was 35%, total dry matter at harvest was 10% and harvest index was 14% with drought stress (pooled means). Among the Ricinus germplasm (RG) studied, RG 1494 and RG 2139 recorded <20% reduction in seed yield with low drought susceptibility index of <0.5. The root volume (310, 557 cm3), root dry weight (122, 93 g/pl.) of RG 1494 and RG 2139 recorded in root structures was also more. Chlorophyll content measured with SPAD chlorophyll meter reading and bloom content increased in water stressed plants as an adaptive feature. RG 1494, RG 2139 showed good performance during both years and also recorded better root and shoot growth characters, and can be used in drought breeding programs.

ROLE OF FLAG LEAF IN WHEAT YIELD

A field trail was conducted at the Field Crop Research Station, Abu-Graib of Agricultural Research Office during 2011-2012 and 2012-2013 in order to investigate the relationship between flag leaf and yield of four wheat varieties. Split plot arrangement with RCBD three replications was used. Varieties (Fatih, Abu-Graib3, Mexipack and IPA 99) was occupied main plots while, flag leaf removal treatments (control treatment (no removal), removal at complete emergence flag leaf (24 March), 29 March, 3 April, 8 April, 13 April and 18 April) was occupied as sub plots. The results showed significantly effect of flag leaf treatments to all studied characteristics (except spike length at second season only). The highest impact reached for removal at emergence flag leaf soon (24 March). Spike length reduced 10.31 and16.85, spikelet number per spike 15, 13%, number of grain per spike 24, 28%, grain weight 7.04, 9.65% and spike yield 30.1, 35.29% for first and second season respectively. Can be show reduced of flag leaf impact when advanced to maturity. Varieties were differed significantly in all characteristics studied. The highest spike length was attained for IPA-99, Fatih, number of spikelet per spike for Fatih, IPA-99, number of grain per spike for Mexipack, grain weight for Abu-Graib3, IPA-99 and spike yield for Mexipack for first and second season respectively. Significant interaction was occurred for all studied characters between flag leaf treatments and varieties. Mexipack and Abu-Graib3 varieties with control treatment gave the highest spike yield (2.130 and 2.15 g) for first and second season, respectively. It can be conclude the importance and significant of vital role of flag leaf to contribution of spike yield about 30.1-35.29% especially at early complete emergence stage of flag leaf in wheat.

REGULATION OF TILLERING IN WHEAT AND ITS RELATIONSHIP WITH GRAIN YIELD 1.CONTRIBUTION PERCENTAGES OF THE MAIN STEM AND PRIMARY TILLERING THE NUMBER OF SPIKES AND GRAIN YIELD

A Factorial experiment was conducted at the experimental farm of Field Crop College of Agriculture University of Baghdad winter Season of 2014-2015. The study was aimed to investigate the effect of seeding rates and nitrogen levels on regulation of tillering in wheat and its relationship with grain yield and components. Treatments were distributed in the Factorial experiment within Randomized Complete Black Design with three replicates and four seeding rates 60,80,100 and 120 kg ha-1 and fertilized with four nitrogen levels 50,100,150 and 200 kgN.ha-1. The results showed that there were significant differences within two factors and their interaction on the number of spikes and grain yield. Main stem produced the highest number of Spike 210.00 spike.m-2, and grain yield 3.050 tan ha-1 compared to primary tillers (tiller1,tiller2,tiller3). Concerning the seeding rate 80 kg ha-1 resulted in the highest number of Spike.m-2 363 spike and Grain yield 4.775 tan.h-1 compared to other seed rates. The N level 150 kg ha-1 gave the highest number of spikes 382 spike and grain Yield 4.919 tan.h-1 compared to other N levels. The percentage of contribution main stem 50.82, 64.57 % respectively compared to the tillers (tiller1, tiller2, tiller3) which amounted to 32.55, 12.80 and 3.80 % respectively in the spikes number, and 26.02, 7.90 and 1.33 % respectively in grain yield. It could be conclude that the total contribution of the primary tillers percentages represents a half the total number of spikes within two factors of study, while the total contribution percentages of primary tillers is amounted to half the main stem contribution in the grain yield within two factors of study.

ESTIMATION OF SOME GENETIC PRAMETERS IN DURUM WHEAT

To estimate genetic parameters and heritability in durum wheat (Triticum turgidum var. durum) genotypes, seventeen genotypes (16 exotic from ICARDA and local variety (Buhooth 7)) were included in this study. This experiment was conducted using a randomized complete block design with three replications at Field Crops Research Station, Abu-Graib, Office of Agricultural Research, during 2011-2012 and 2012-2013. The results revealed significant differences among genotypes for the studied characters at both seasons. The best genetic/environmental variance ratio attained for spike length (11.90) and no. of spikes. m-2 (9.22) in the first season, and grain yield (8.82) then harvest index (4.87) in the second season. High GCV observed for grain yield (15.68), no. of spikes. m-2 (15.18) in the first season, and harvest index (16.89) and grain yield (14.22) in the second season. High heritability estimates associated with high genetic advance for no. of spikes. m-2, in the first season. While, moderate h2bs estimates associated with high GA for same trait in the second season. Expected response to selection ranged from 0.93 to 84.6, also selection index ranged from 1.23 to 106.44 for grain yield and number of spikes. m-2, respectively in the first season also the same pattern was observed for value of second season. Characteristics like no. of spikes. m-2, plant height, no. of grains. Spike-1 and grain weight showed high heritability coupled with high genetic progress. Therefore, these characters should be given top priority during selection breeding in durum wheat.

Relationship of morphological traits and yield components with seed and protein yields in Iranian bread wheat (Triticum aestivum L.) cultivars

Correlation analysis showed the significant relation of seed and protein yield with all the traits except correlation of grain filling duration and peduncle length with seed yield as well as spike yield and peduncle length with protein yield. Factor analysis indicated that four important factors accounted for about 94.31% of the total variation among traits studied. The first factor assigned 34.99% of total variation between traits and was significantly related with traits seed yield, biological yield, protein yield and protein percentage. This factor was regarded as quantitative and qualitative yield improvement factor. Other factors accounted for 43.70, 27.90 and 22.40% of variation between traits so were entitled as spike yield, grain filling ability and photosynthesis reservoir enhancement factors, respectively. Overall, results revealed effect of grain filling rate, biological yield, number of seeds/spike, spike yield and protein percentage on seed and protein yield. Hence, these traits are recommended as indirect selection criteria for genetic improvement of seed yield especially in early generations.

Effect of foliar application of micronutrients on growth, flowering and yield of gladiolus (Gladiolus grandiflorus L.)

An experiment was laid out to study the effect of micronutrients (B, Zn and Fu) in Randomized Block Design (RBD) with three replications and 10 treatments on growth flowering and yield characters of gladiolus at the Horticulture Research Farm, Andro, College of Agriculture, Central Agricultural University, Imphal. The treatments consisted of T1 (Control), T2 (100 ppm B), T3 (200 ppm B), T4 (300 ppm B), T5 (100 ppm Zn), T6 (200 ppm Zn), T7 (300 ppm Zn), T8 (100 ppm Fe), T9 (200 ppm Fe) and T10 (300 ppm Fe). Observations were recorded on vegetative parameters at 30 and 60 DAP, flowering, flower yield and corm and cormel parameters. From the present study, it was found that among the various treatments, foliar application of T7 (300 ppm Zn) significantly influenced all the vegetative parameters i.e. plant height (cm), number of leaves and length of leaf at 30 and 60 DAP. Also, significantly maximum duration of flowering, length of the spike, yield of spike per m2, yield of spikes per hectare, diameter of the corm, weight of the corm, number of cormels per plant and yield of corm per hectare were found with foliar application of T7 (300 ppm Zn). However, maximum fresh weight of the spike was found in T4 (300 ppm B). Control recorded minimum value in all the vegetative, flowering and corm parameters. Hence, foliar application of 300 ppm Zn at 30 and 60 DAP can be a part of recommendation for commercial cultivation of gladiolus.

Genetic diversity of characteristics in barley cultivars

Knowledge of the genetic diversity is important to design appropriate selection criteria in the breeding programs. In this study, the genetic diversity of 42 Iranian and European barley cultivars was investigated with morpho-agronomic traits including phenological, physiological, morphological traits, grain yield and associated traits. Analysis of variance showed high variability among cultivars. The European cultivars Panaka, Aiace and Pariglia had the highest grain yield. The results of group comparisons indicated that the European cultivars produced higher grain yield (500.57 g/m2) than the Iranian cultivars (445.50 g/m2), but larger genetic diversity based on morpho-agronomic traits was observed among Iranian cultivars than European cultivars. Correlation analysis revealed the high significant correlations between grain yield with biological yield (0.92), straw yield (0.77), and number of spike per square meter (0.67). Based on the factor analysis, the six factors that justified 81.63 percent of the variations were identified. The first factor having the largest eigenvalue was identified as effective factor on the vegetative and reproductive growth. In path analysis, biological yield had the greatest effect on grain yield (0.906). Cluster analysis classified the cultivars in six groups and showed that genetic variation based on the all studied traits among the barley cultivars was not related to geographical location.

Inheritance studies in F2 segregating populations of bread wheat genotypes

This study was carried out to determine the inheritance pattern of various agronomic traits in six F2 segregating populations of spring wheat. In this context, an experiment was conducted at the experimental field of Southern Wheat Research Station, Tandojam during Rabi 2014-2015. The experiment was laid out in randomized complete block design with three replications. The experimental material was consisted of nine parents, including Khirman, Imdad-05, Noori, Soughat, Mexipak, Moomal, Marvi, Kiran-95 and Anmol-91 and their six F2 progenies. The analysis of variance of the genotypes (including nine parents and their six F2 progenies) showed that all the defined characters were differed significantly (P<0.05), offering the higher genetic variability among the genotypes which can further be exploited for various breeding programs to improve bread genotypes. On the basis of mean performance, among the parental lines, the parent Khirman exhibited outstanding performance for a range of characters (tillers plant, spike length, spikelets spike, grains spike and grain yield plant). Considering the F2 hybrids, the progeny Khirman × Imdad-05 showed promising results for tillers plant, spike length and spikelets spike, whereas Anmol × Marvi gave desirable results for grain yield plant and seed index, indicating that above mentioned genotypes may be proved reliable genetic resources. With regards to heritability percentage in broad sense, the F2 progeny Khirman x Imdad-05 expressed high heritability for almost all studied traits, with the exception of grain yield plant. This study suggests that most of the yield associated traits have been successfully transmitted. The information generated will be helpful for better understanding and selection of desirable material especially in advance generations.

Accuracy of MEG in localizing irritative zone and seizure onset zone: Quantitative comparison between MEG and intracranial EEG

BackgroundWe conducted the study to examine accuracy of the magnetoencephalography (MEG) spike source localization in presurgical evaluation of patients with medically refractory focal epilepsy. MethodsTen consecutive patients with refractory focal epilepsy who were candidates for two-stage surgery with long-term intracranial electroencephalography (ICEEG) monitoring were enrolled. Interictal MEG recordings with simultaneous scalp EEG were obtained within 7days before the ICEEG electrode implantation. The location of each MEG spike source was quantitatively compared with ICEEG spike foci (focal area of interictal spikes) and ICEEG ictal foci (earliest cortical origin of seizures). Gyral-width concordance and sublobar concordance were also determined for all MEG spike sources. Gyral-width concordance was defined by distance of 15mm or less between MEG spike sources and ICEEG spike foci or ICEEG ictal foci. ResultsVisual analyses of the MEG traces of all 10 patients revealed 292 spikes (29.2±24.0 per patient). Spike yield of the MEG was similar to the simultaneously recorded scalp EEG. MEG spike sources were closely located with ICEEG spike foci (distance: 9.3±10.8mm). Clustered MEG spike sources were even closer to ICEEG spike foci (distance: 7.3±6.4mm). MEG spike sources, even clustered ones, were less concordant with ICEEG ictal foci and had significant longer distance from ICEEG ictal foci (distance: 21.5±15.6mm for all sources, 19.7±13.7mm for clustered sources). Gyral-width concordance rate and sublobar concordance rate were also higher with ICEEG interictal spike foci than with ICEEG ictal foci. On the other hand, 53.4% of interictal spike foci from ICEEG were not detected by interictal MEG recordings. ConclusionsMEG spike sources, especially clustered ones, from interictal recording could localize the irritative zone of ICEEG with a high accuracy. However, MEG spike sources have relatively poor correlation with seizure onset zone and lower sensitivity in identifying all irritative zones of ICEEG. This limitation should be considered in the interpretation of MEG results.

DETECTING AND ESTIMATION OF DIFFERENT COMPONENTS OF GENETIC VARIATION (ADDITIVE, DOMINANCE AND EPISTASIS) UNDER STRESS AND NON-STRESS CONDITIONS IN BREAD WHEAT

Twenty four common wheat varieties were used to establish the experimental materials for the two biometrical tools used in this concern i.e., triple test cross analysis and six populations analysis. Mean values of backcrosses to F1’s (L3i) showed increased in mean values and surpassed the other backcrosses for all traits studied, showing highly grain yield / plant and other yield contributed traits. It is clear that the backcrosses to L2 (Sids 12) tended to decreased in mean values for most traits showing low grain yield / plant with other yield attributes. On the other side, mean values of hybrids (L1, L2 and L3) surpassed lines in most traits indicating some sort of hybrid vigour. The means of lines and testers differed significantly from each other. The mean square for deviations L1i + L2i – 2L3i revealed presence of highly significant over all epistasis for all traits studied. The data revealed highly significant mean squares due to sums (L1i + L2i) for all traits studied. However mean square due to differences (L1 i- L2i) were significant only for 1000 grain weight, heading date, main culm spike length, number of spikelets / main culm spike, number of spikes / plant and plant height. The highest proportion of recombinants that possible outperform parental range was obtained for number of grains / spikelets followed by main culm spike length and main spike yield. These results reflecting fair amount of genetic variability and considered valuable further breeding studies aiming to improve such chatacters. Significant positive between epistasis gene effects controlling main spike yield and number of grain / main culm spike, and between number of grain / spikelets with number of spikes / plant. The main spike yield, main culm spike length, number of grains / main culm spike and number of spikeletes / main culm spike had a strong relation with grain yield. Dominance gene effects (d) were found to be significant in the four crosses for number of spikelets/main culm spike under 35kg.n./f only. The three epistatic types were found to be significant for most traits under investigation. High heritability estimates in broad sense were detected for nearly all traits studied. High estimates of narrow sense heritability were found for all crosses for heading date, plant height, number of spikes per plant, main culm spike length, number of kernels per spikelets, number of kernels per main culm spike and grain yield per plant under 35 kg.n./f. High genetic advance under selection was found to be associated with high narrow sense heritability estimates for number of spikes per plant and grain yield per plant for all crosses under 35 kg.n./f. for all crosses, number of kernels per spikelets under 35 kg.n./f. for third and fourth crosses.

Evaluation of genetic divergence in Barley (Hordeum vulgare L.) germplasms

Thirty genotypes of wheat were evaluated for assessing genetic divergence among eleven different characters across one environment for exploitation in a breeding programme for improving yield of barley by using Mahalanobis D2 statistics. The germplasms were grouped into six clusters. Out of six clusters, cluster I had five genotypes, cluster II had two genotypes, cluster III had ten genotypes, cluster IV had two genotypes, cluster V had eight genotypes and cluster VI had three genotypes based on present investigation. The intra cluster distance among various clusters exhibited maximum intra cluster distance for cluster VI and lowest was recorded for cluster II. The maximum inter cluster distance was revealed between cluster I and V followed by cluster I and VI, cluster III and IV, cluster III and VI , cluster II and IV, cluster III and V and cluster II and V. The least inter cluster distance between clusters IV and VI followed by cluster IV and I and cluster I and II cluster. The phenotypic and genotypic path coefficient exhibited high positive direct contribution of harvest index, number of tillers per plant, number grain per spike and biological yield per plant.

Milho consorciado com capim tifton na Amazônia sul ocidental

RESUMO Objetivou-se, com este trabalho, avaliar o desempenho do consórcio de milho com capim tifton na Amazônia sul ocidental. O delineamento experimental utilizado foi em blocos casualizados, com seis tratamentos e quatro repetições. Os tratamentos foram constituídos pelos monocultivos de milho e de capim tifton e por quatro épocas de transplantio de capim tifton nas entrelinhas de semeadura do milho (SM), sendo: simultâneo, aos 15, 30 e 45 dias após a SM. Para o milho, avaliaram-se: biomassa de 100 grãos, número de fileiras de grãos por espiga, produtividade de grãos, altura da planta e inserção da primeira espiga. A biomassa seca do capim tifton foi estimada a partir de dois cortes, com intervalo de 20 dias entre a primeira e a segunda coleta. Para avaliar a eficiência dos consórcios em relação aos monocultivos, utilizou-se o índice de equivalência de área. Os resultados obtidos foram submetidos ao teste de Shapiro-Wilk (p&lt;0,05), a fim de aferir a normalidade dos dados, seguido pela análise de variância. Foram ajustados modelos de regressão para as épocas de implantação do capim tifton nas entrelinhas do milho, quando houve efeito significativo pelo teste F, a 5% de probabilidade. Utilizou-se o teste de Dunnet (p ≤ 0,05) para as comparações entre o milho consorciado com tifton e os monocultivos (testemunha). O milho não sofre interferência quando consorciado com capim tifton. Entretanto, o tifton apresenta menor acúmulo de biomassa seca quando consorciado com o milho. O melhor desempenho do consórcio verificou-se na implantação simultânea do milho com capim tifton.

Genetic variability, character association and path coefficient analysis in orchids (Orchid spp) of Mizoram, Sikkim and Darjeeling District of West Bengal for various quantitative traits

Efforts were made on augmentation of orchids germplasm in different parts of Mizoram, Pakyong (Sikkim) and Pedong (Darjeeling hills of West Bengal) during 2011-2013 to estimate the genetic variability, heritability, genetic advance, correlation and path coefficient in seventy nine diverse genotypes of orchids on 14 important quantitative traits. Germplasms were evaluated for various vegetative, floral and spike quality related traits. Flower quality characters like length of spike, length of internode of the spike, length of pedicel were found to be high in the species like Arundina graminifolia and Cymbidium aloifolium. However, the number of florets/spike was more in Oberonia orbicularis and Oberonbia iridifolia and Phaius tankervillae recorded biggest floret size. Spike longevity was found to be high in Dendrobium formosum and Vanda parishii. Spike yield was maximum in Dendrobium chrysanthum and Dendrobium eriaeflorum. The study revealed wide variation for all the characters indicating sufficient genetic variability to be exploited in breeding programme. The maximum value of PCV and GCV was recorded for floret diameter. High heritability coupled with high genetic advance was observed for plant height, leaves/pseudobulb, florets/spike, floret diameter and pedicel length. Selection on the basis of these characters would be more effective for the improvement of orchids. Spike length showed positive and highly significant association with spike longevity and number of florets/spike at genotypic and phenotypic level. Highly significant correlation of spike yield was found with pseudobulbs/plant, leaf dimensions, flowers/spike and number of spike/pseudobulb at both the levels of correlation coefficient.

A splice acceptor site mutation in TaGW2-A1 increases thousand grain weight in tetraploid and hexaploid wheat through wider and longer grains.

Key messageAcross 13 experiments thegw2-A1mutant allele shifts grain size distribution consistently across all grains significantly increasing grain weight (6.6 %), width (2.8 %) and length (2.1 %) in tetraploid and hexaploid wheat.There is an urgent need to identify, understand and incorporate alleles that benefit yield in polyploid wheat. The rice OsGW2 gene functions as a negative regulator of grain weight and width and is homologous to the wheat TaGW2 gene. Previously it was shown that transcript levels of the A-genome homoeologue, TaGW2-A1, are negatively associated with grain width in hexaploid wheat. In this study we screened the tetraploid Kronos TILLING population to identify mutants in TaGW2-A1. We identified a G to A transition in the splice acceptor site of exon 5 which leads to mis-splicing in TaGW2-A1. We backcrossed the mutant allele into tetraploid and hexaploid wheat and generated a series of backcross derived isogenic lines which were evaluated in glasshouse and field conditions. Across 13 experiments the GW2-A1 mutant allele significantly increased thousand grain weight (6.6 %), grain width (2.8 %) and grain length (2.1 %) in tetraploid and hexaploid wheat compared to the wild type allele. In hexaploid wheat, this led to an increase in spike yield since no differences were detected for spikelet or grain number between isogenic lines. The increase in grain width and length was consistent across grains of different sizes, suggesting that the effect of the mutation is stable across the ear and within spikelets. Differences in carpel size and weight between alleles were identified as early as 5 days before anthesis, suggesting that TaGW2-A1 acts on maternal tissue before anthesis to restrict seed size. A single nucleotide polymorphism marker was developed to aid the deployment of the mutant allele into breeding programmes.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-016-2686-2) contains supplementary material, which is available to authorized users.