Improvement Of Grain Yield Research Articles

Adaptability and Stability of Corn Hybrids in Southern Brazilian Environments

The objective of this study was to identify, among the 27 hybrids evaluated, the best adaptability and stability responses for corn grain yield in five environments. The experiments were conducted in the 2009/2010 crop seasons in a randomized complete block design with three replications. There was significant G x E interaction effects (p ≤ 0.05) only for the yield and cob mass characters. Among the hybrids tested, 14 of them were ranked as responsive to environmental improvement for grain yield. The other genotypes have good performance in harsh environments. For the stability analysis, significance was found for the hybrids 5, 7 and 27. For cob mass, all hybrids showed significant adaptability, for stability, only genotypes 20 and 24 expressed significance.

Low contribution of photosynthesis and water-use efficiency to improvement of grain yield in Chinese wheat

The contribution of photosynthesis to yield improvement is important to know in order to determine future breeding strategies. The objectives of this study were to determine the contribution of photosynthesis and water-use efficiency (WUE) to grain yield improvement of facultative wheat (Triticum aestivum L.) cultivars on the Loess Plateau of China released between 1937 and 2004. The grain yield has increased nearly sevenfold during this period. Surprisingly, these increases were not correlated with the rate of photosynthesis per unit of leaf area when the cultivars were planted and managed in the same environment. The increases were also not correlated with transpiration rate, stomatal conductance, or WUE, except at the jointing stage. The total increase in photosynthesis may be due to enlargement of photosynthetic area and photosynthesis duration. The grain yield was positively correlated with the number of grains per unit of area (r = 0.855, P<0.05), harvest index (HI) (r = 0.885, P<0.01), and thousand-grain mass (r = 0.879, P<0.01). The increase in grain yield was limited by the grain number and the grain size (sink-limited) and the yield improvement was attributed to a rise in HI over the last 70 years in a highland agricultural system in China.

Single nucleotide polymorphism markers linked to QTL for wheat yield traits

Continuous improvement in grain yield is one of the major challenges for wheat (Triticum aestivum L.) breeding worldwide. This study characterized quantitative trait loci (QTL) underlying wheat grain yield and its components using a high-density genetic linkage map developed from a recombinant inbred line (RIL) population derived from ‘Ning7840’ × ‘Clark’. The map consisted of 594 single nucleotide polymorphism and 404 simple sequence repeat markers covering a genetic distance of 4225.7 cM. The RIL population was evaluated for grain yield (GY), spike number per m2 (SNPM), kernel number per spike (KNPS), and thousand-kernel weight (TKW) in three Oklahoma locations from 2001 to 2003. A total of 29 additive QTL (eight for GY, two for SNPM, five for KNPS, and 14 for TKW) were mapped on 13 chromosomes. Eight pairs of epistatic QTL were detected for different yield components: four for GY, two for KNPS, and two for TKW. Four additive QTL, including two for GY and two for KNPS, showed additive × environment interactions. QTL that were repeatable in multiple environments were identified for all traits except SNPM. Positive alleles were dispersed between the two parents for all traits, with ‘Clark’ contributing slightly more. Seven pleiotropic loci were co-localized for at least two traits. Interestingly, all co-localized loci overlapped for TKW, and four of them overlapped for GY. Thus, selecting QTL for TKW may simultaneously select for or against yield or other yield components in breeding.

Grain quality changes and responses to nitrogen fertilizer of japonica rice cultivars released in the Yangtze River Basin from the 1950s to 2000s

While the yield potential of rice has increased but little is known about the impact of breeding on grain quality, especially under different levels of N availability. In order to investigate the integrated effects of breeding and N levels on rice quality 12 japonica rice cultivars bred in the past 60years in the Yangtze River Basin were used with three levels of N: 0kgNha−1, 240kgNha−1, and 360kgNha−1. During the period, milling quality (brown rice percentage, milled rice percentage, and head rice percentage), appearance quality (chalky kernels percentage, chalky size, and chalkiness), and eating and cooking quality (amylose content, gel consistency, peak viscosity, breakdown, and setback) were significantly improved, but the nutritive value of the grain has declined due to a reduction in protein content. Micronutrients, such as Cu, Mg, and S contents, were decreased, and Fe, Mn, Zn, Na, Ca, K, P, B contents were increased. These changes in grain quality imply that simultaneous improvements in grain yield and grain quality are possible through selection. Overall, application of N fertilizer decreased grain quality, especially in terms of eating and cooking quality. Under higher N levels, higher protein content was the main reason for deterioration of grain quality, although lower amylose content might contribute to improving starch pasting properties. These results suggest that further improvement in grain quality will depend on both breeding and cultivation practices, especially in regard to nitrogen and water management.

In silico system analysis of physiological traits determining grain yield and protein concentration for wheat as influenced by climate and crop management.

Genetic improvement of grain yield (GY) and grain protein concentration (GPC) is impeded by large genotype×environment×management interactions and by compensatory effects between traits. Here global uncertainty and sensitivity analyses of the process-based wheat model SiriusQuality2 were conducted with the aim of identifying candidate traits to increase GY and GPC. Three contrasted European sites were selected and simulations were performed using long-term weather data and two nitrogen (N) treatments in order to quantify the effect of parameter uncertainty on GY and GPC under variable environments. The overall influence of all 75 plant parameters of SiriusQuality2 was first analysed using the Morris method. Forty-one influential parameters were identified and their individual (first-order) and total effects on the model outputs were investigated using the extended Fourier amplitude sensitivity test. The overall effect of the parameters was dominated by their interactions with other parameters. Under high N supply, a few influential parameters with respect to GY were identified (e.g. radiation use efficiency, potential duration of grain filling, and phyllochron). However, under low N, >10 parameters showed similar effects on GY and GPC. All parameters had opposite effects on GY and GPC, but leaf and stem N storage capacity appeared as good candidate traits to change the intercept of the negative relationship between GY and GPC. This study provides a system analysis of traits determining GY and GPC under variable environments and delivers valuable information to prioritize model development and experimental work.

Variability in Growth and Yield Response of Maize Genotypes at Elevated CO2 Concentration

Three contrasting maize (Zea mays L.) genotypes- DHM-117 (single cross hybrid), Varun (synthetic) and Harsha (composite) with different yield potentials were selected to assess their growth and yield performance at ambient (390ppm) and elevated (550ppm) CO2 condition in Open Top Chamber (OTC) facility. The phenology, biomass accumulation, grain yield and HI was quantified of these three maize genotypes at both CO 2 levels. The phenology of flowering was early by 1.5 to 2 days, while the anthesis silking interval (ASI) was not influenced by elevated CO 2 in DHM-117 and Varun, where as it was reduced by two days in Harsha. Response of selected three maize genotypes was different to elevated CO 2 (550ppm) condition in terms of biomass, grain yield and HI. The improvement in biomass ranged from 32% to 47%, grain yield 46% to 127% with 550ppm CO2 as compared with ambient control. The improvement in grain yield was due to increased grain number (25-72%) as well as improved test weight (8-60%). The overall response of less efficient maize genotype Harsha with elevated CO 2 concentration was found to be significantly high especially the grain yield and its components. Elevated CO 2 also improved the maize HI (11% to 68%) indicating that influence of elevated CO2 was there on partitioning of biomass of this C 4 crop.

Transgenic plants expressing the AaIT/GNA fusion protein show increased resistance and toxicity to both chewing and sucking pests.

The adoption of pest-resistant transgenic plants to reduce yield losses and decrease pesticide use has been successful. To achieve the goal of controlling both chewing and sucking pests in a given transgenic plant, we generated transgenic tobacco, Arabidopsis, and rice plants expressing the fusion protein, AaIT/GNA, in which an insecticidal scorpion venom neurotoxin (Androctonus australis toxin, AaIT) is fused to snowdrop lectin (Galanthus nivalis agglutinin, GNA). Compared with transgenic tobacco and Arabidopsis plants expressing AaIT or GNA, transgenic plants expressing AaIT/GNA exhibited increased resistance and toxicity to one chewing pest, the cotton bollworm, Helicoverpa armigera. Transgenic tobacco and rice plants expressing AaIT/GNA showed increased resistance and toxicity to two sucking pests, the whitefly, Bemisia tabaci, and the rice brown planthopper, Nilaparvata lugens, respectively. Moreover, in the field, transgenic rice plants expressing AaIT/GNA exhibited a significant improvement in grain yield when infested with N. lugens. This study shows that expressing the AaIT/GNA fusion protein in transgenic plants can be a useful approach for controlling pests, particularly sucking pests which are not susceptible to the toxin in Bt crops.

Selection criteria for grain yield and stability in bambara groundnut (Vigna subterranean (L) Verdc) landraces

The potential of bambara groundnut as a crop-based approach for the sustainable reduction of protein–energy malnutrition prevalent in Nigeria is still being explored. However, one of the limitations to sustainable production of this adapted species is low and unstable yield. Here, we employed multiple statistical analyses to determine traits that could be useful in predicting grain yield. Furthermore, additive main effect and multiplicative interaction and genotype × genotype × environment models were used to identify high yielding and stable landraces. Twenty-four bambara landraces were evaluated in two contrasting dry land growing seasons at four environments. Based on the results of correlation, path coefficient values and stepwise multiple regression analysis, it is reasonable to assume that seed growth rate would be effective as indirect selection criteria for grain yield improvement in this set of breeding materials under early and late planting environment. However, optimizing biomass growth rate, pod fill period, 100-seed weight, number of pods per plant and time to flowering may have important role in the improvement of grain yield in bambara groundnut. Due consideration should be given to 100-seed weight and time to flowering in the early dry and late planting environment. The possibility of successful cultivation of bambara groundnut in forest–savannah transition agricultural zone of Nigeria, particularly when planting is done around early August has been established in this study. However, based on the strong association between seed yield and its related characters in early and late planting environments, selection for higher seed growth rate combined with large number of pods appears to be the best indirect traits when selecting bambara groundnut plants to enhance grain yield under early and late planting environments. While landraces TVSu 1520 and 1578 were considered the best adapted landraces, TVSu 1670 and 1518 are promising landraces that could contribute to increasing grain yield stability.

Gains in Grain Yield of Early Maize Cultivars Developed During Three Breeding Eras under Multiple Environments

ABSTRACTMaize (Zea maysL.), an important staple crop in West and Central Africa (WCA), has enormous potential to reduce food insecurity in this subregion. Research covering three periods or eras of breeding has been conducted to develop cultivars resistant/tolerant to three maize stress factors:Strigaparasitism, drought, and low soil nitrogen. A study was conducted under optimal or natural growing environments at 35 locations in WCA for 2 yr to determine genetic improvement in grain yield of the maize cultivars developed during the three breeding periods: 1988–2000 (period 1), 2001–2006 (period 2), and 2007–2010 (period 3). The average rate of increase in grain yield under optimum growing conditions was 40 kg ha−1yr−1with a genetic gain of 1.3% yr−1, which was slightly higher than the gain of 30 kg ha−1yr−1, an annual genetic gain of 1.2% across 16 stress environments. It was concluded that substantial improvement in the yield potential of early maize under relatively nonstress environmental conditions has been made in this subregion by breeding for stress tolerance during the past three decades. The varieties EV DT‐W 2008 STR, 2009 DTE‐Y STR Syn, and TZE‐W DT C2 STR, all from the latest era of improvement, were identified as the highest yielding and most stable cultivars and should be promoted to contribute to food security in this subregion.

Pseudo-backcrossing design for rapidly pyramiding multiple traits into a preferential rice variety.

BackgroundPyramiding multiple genes into a desirable genetic background can take years to accomplish. In this paper, a pseudo-backcrossing scheme was designed to shorten the backcrossing cycle needed. PinK3, an aromatic and potentially high-yielding rice variety—although one that is intolerant to flash flooding (Sub) and susceptible to bacterial leaf blight (BB), leaf-neck blast (BL) and the brown planthopper (BPH)—was used as a genetic basis for significant improvements through gene pyramiding.ResultsFour resistance donors with five target genes (Sub1A-C, xa5, Xa21, TPS and SSIIa) and three QTLs (qBph3, qBL1 and qBL11) were backcrossed individually using markers into the pseudo-recurrent parent ‘PinK3’ via one cycle of backcrossing followed by two cycles of pseudo-backcrossing and three selfings with rigorous foreground marker-assisted selection. In total, 29 pseudo-backcross inbred lines (BILs) were developed. Genome composition was surveyed using 61 simple sequence repeats (SSRs), 35 of which were located on six carrier chromosomes, with the remainder located on six non-carrier chromosomes. The recurrent genome content (%RGC) and donor genome content (%DGC), which were based on the physical positions of BC1F2, ranged from 69.99 to 88.98% and 11.02 to 30.01%, respectively. For the pseudo-BC3F3BILs, the %RGC and %DGC ranged from 74.50 to 81.30% and 18.70 to 25.50%, respectively. These results indicated that without direct background selection, no further increases in %RGC were obtained during pseudo-backcrossing, whereas rigorous foreground marker-assisted selection tended to reduce linkage drag during pseudo-backcrossing. The evaluation of new traits in selected pseudo-BC3F3BILs indicated significant improvements in resistance to BB, BL, BPH and Sub compared with PinK3, as well as significant improvements in grain yield (21-68%) over the donors, although yield was 7-26% lower than in ‘PinK3’. All pyramided lines were aromatic and exhibited improved starch profiles, rendering them suitable for industrial food applications.ConclusionsResults show that our new pyramiding platform, which is based on marker-assisted pseudo-backcrossing, can fix five target genes and three QTLs into a high-yielding pseudo-recurrent background within seven breeding cycles in four years. This multiple pseudo-backcrossing platform decreases the time required to generate new rice varieties exhibiting complex, durable resistance to biotic and abiotic stresses in backgrounds with desirable qualities.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-014-0035-0) contains supplementary material, which is available to authorized users.

Effect of genetic improvement of grain yield and nitrogen efficiency of mid‐seasonindicarice cultivars

AbstractGenetic improvement (GI) of mid‐seasonindicarice (Oryza sativaL.) in China has been experienced four typical plant types during the past several decades,i.e., early tall cultivars (ET), dwarf cultivars (DC), semi‐dwarf cultivars (SDC) and super rice cultivars (SR). However, little is known about the changes in fertilizer nitrogen (N) efficiency and their relationships with grain yield during the GI. With 12 representative mid‐seasonindicacultivars of the four types during GI, the effects of GI on grain yield and nitrogen efficiency were investigated. The results show that GI significantly increased grain yield and agronomic efficiency (AE) of N fertilizer but had no significant effect on recovery efficiency (RE) of N fertilizer. The low percentage of filled grains in modern SR limited its yield potential and the further increase in AE. GI decreased the N uptake from heading to maturity, leading to lower RE in modern rice cultivars. The rapid decline of the activities of root oxidation and nitrate reductase in SR during grain filling might be the physiological reasons for the lower percentage of filled grains and lower N uptake from heading to maturity.

Genetic studies in upland rice (Oryza sativa L.)

Studies on genetic variability, character association and path co-efficient analysis were conducted on 40 rice genotypes. Analysis of variance revealed considerable variability among the genotypes for all the characters. A high genotypic and phenotypic co-efficient of variation was observed for grain yield per plant, straw yield per plant, productive tillers per plant, spikelets per panicle, harvest index, 1000 grain weight, number of panicles per running meter, spikelet fertility, plant height, days to 50 per cent flowering and panicle length. Spikelets per panicle showed the highest broad sense heritability (95.81%). Grain yield per plant showed high value of heritability coupled with low genetic advance. The genotypic correlations among the yield traits and their path co-efficient were estimated. The grain yield per plant showed significant positive correlation with harvest index, 1000 grain weight, straw yield per plant, plant height and productive tillers per plant. The traits days to maturity, plant height, straw yield per plant and harvest index had moderate to high positive direct effect on grain yield per plant. The study revealed that genetic improvement of grain yield in rice is admissible by selecting characters having high positive correlation and positive direct effect.

Analysis of Some Agronomic Traits of Durum Wheat Under Dryland and Supplemental Irrigation Conditions

Abstract Knowledge about the extent of variability and the association among traits are of a high value for any breeding efforts. The objective of this investigation is to evaluate the agro-morphological traits in a set of durum wheat genotypes under supplemental irrigation and dry land conditions. Results showed that principal component (PC) analysis had grouped the measured traits into four main components that altogether accounted for 77% of the total variation under non-stressed condition and 87% under water-stressed condition. With regard to the first four PCs, peduncle length, agronomic score, grain yield, vigority, test weight, days to physiological maturity and thousand kernel weight have shown to be the most important variables affecting the performance of durum wheat under non-stressed condition. In the first four PCs at the water- stressed condition, agronomic score, grain yield, vigority, days to physiological maturity, test weight and peduncle length have been shown to be the important variables under water-stressed condition. The results of factor analysis relatively confirmed the results of PC analysis. Our findings indicated that a selection strategy should take into consideration of agronomic score and days to physiological maturity under non-stressed condition while plant height and spike length under water-stressed condition. Therefore, the above-mentioned traits could be used as indirect selection criteria for genetic improvement of grain yield in durum wheat, especially in early generations of breeding programmes

Enhancing grain yield and quality of winter barley through agronomic strategies to prolong canopy greenness

An agronomic improvement in grain yield and quality in winter wheat could be obtained through the application of strategies, such as application of foliar fungicides or fertilizers, that protect health of the last leaves and delay the senescence process during ripening. Only a few studies have reported the effect of these practices on barley, although these treatments could represent a new opportunity to specialize in feed and food barley markets and raise farmer profitability.The aim of this study was to compare the effect of different late-season strategies, N and S foliar fertilizers and fungicides applied at barley anthesis, on crop canopy greenness during the ripening stages and to establish the relationship between these strategies and barley yield and quality. Four field experiments have been conducted in NW Italy during 3 growing seasons, according to a full factorial design with four treatments, three barley cultivars and four replications. The following parameters were recorded: canopy greenness, grain yield, test weight (TW), thousand kernel weight (TKW), grain protein content (GPC), foliar disease incidence and severity and deoxynivalenol (DON) contamination. The collected data clearly underline the importance of prolonging canopy greenness of barley in order to increase grain yield and to improve quality. Of all the compared treatments, the application of a fungicide with an azole mixture at anthesis has shown to play the most important role in delaying the senescence process, and has resulted in a higher gran yield (+25%), TW (+1.3kghl−1) and TKW (+2.8g).The effect of the fungicide treatment on barley grain yield was significant for all the compared cultivars and in almost all the environmental conditions, but led to a greater advantage in the cooler environments with prolonged ripening. The fungicide also led to a clear, significant control of foliar disease and a reduction in DON contamination.The use of N and S foliar fertilizers was able to prolong canopy greenness and enhance barley yield and quality but only in environments characterized by a prolonged grain filling period.

Mapping a region within the 1RS.1BL translocation in common wheat affecting grain yield and canopy water status.

Key message This study identifies a small distal region of the 1RS chromosome from rye that has a positive impact on wheat yield. The translocation of the short arm of rye (Secale cereale L.) chromosome one (1RS) onto wheat (Triticum aestivum L.) chromosome 1B (1RS.1BL) is used in wheat breeding programs worldwide due to its positive effect on yield, particularly under abiotic stress. Unfortunately, this translocation is associated with poor bread-making quality. To mitigate this problem, the 1RS arm was engineered by the removal and replacement of two interstitial rye segments with wheat chromatin: a distal segment to introduce the Glu-B3/Gli-B1 loci from wheat, and a proximal segment to remove the rye Sec-1 locus. We used this engineered 1RS chromosome (henceforth 1RSWW) to develop and evaluate two sets of 1RS/1RSWW near isogenic lines (NILs). Field trials showed that standard 1RS lines had significantly higher yield and better canopy water status than the 1RSWW NILs in both well-watered and water-stressed environments. We intercrossed the 1RS and 1RSWW lines and generated two additional NILs, one carrying the distal (1RSRW) and the other carrying the proximal (1RSWR) wheat segment. Lines not carrying the distal wheat region (1RS and 1RSWR) showed significant improvements in grain yield and canopy water status compared to NILs carrying the distal wheat segment (1RSWW and 1RSRW), indicating that the 1RS region replaced by the distal wheat segment carries the beneficial allele(s). NILs without the distal wheat segment also showed higher carbon isotope discrimination and increased stomatal conductance, suggesting that these plants had improved access to water. The 1RSWW, 1RSWR and 1RSRW NILs have been deposited in the National Small Grains Collection.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-014-2408-6) contains supplementary material, which is available to authorized users.

Integrated nutrient management for sustaining wetland rice (Oryza sativa) production in mid hills altitude of Meghalaya

A field experiment was conducted, during rainy season of 2007 and 2008 at the research farm of ICAR Research Complex for NEH Region, Umiam, Meghalaya, to study the effect of organic and inorganic sources of nutrients in wetland rice. The results of two years study reveals that the growth parameters were improved with application of 5 tonnes/ha FYM + Azolla dual cropping + 75 per cent of the recommended dose of NPK (80:60:40 kg/ha, RDF). While higher yield attributes were recorded with 50% of the recommended dose of fertilizer in the presence of FYM 5 tonnes/ha + Azolla dual cropping resulted into maximum grain yield of 39.34 q/ha, which was 13.89% and 16.87% higher over alone application of recommended dose of NPK and bio-organics, respectively. Application of FYM 5 tonnes/ha + Azolla + Azospirillum found to produce grain yield equal with FYM 10 tonnes/ha and application of recommended dose of NPK without any bio-organic. The use of Azospirillum was promising in improving growth and yield of rice. The grain yield of rice recorded with FYM 5 tonnes/ha + seedling inoculation with Azospirillum in the presence of 75% recommended dose of NPK (38.34 q/ha) was significantly higher over that of 50% RDF with same bio-organics, but when Azolla dual cropping in place of Azospirillum was adopted, the maximum grain yield was recorded with 50% RDF, which was however, at par with that of 75 and 100% RDF applied together with same bio-organics, indicated that the use of biofertilizer can save 25-50 per cent of the recommended dose of NPK, besides substantial improvement in grain yield of wetland rice. The uptake of K was more than N and P. Maximum N and P uptake was recorded with FYM 5 tonnes/ha + Azolla dual cropping + 75 RDF, while maximum K uptake was recorded with the same bio-organics applied in the presence of 100 RDF. Highest net return with benefit : cost ratio was found with FYM 5 tonnes/ha + Azolla dual cropping + 50 RDF.

Iron Chelates Alleviate Iron Chlorosis in Soybean on High pH Soils

High pH soils frequently lead to iron deficiency chlorosis (IDC) in soybean [Glycine max (L.) Merr.]. As a result, yields for soybean are often reduced. Studies in the north‐central United States have shown improvements in grain yield after applying Fe chelates on calcareous soils, but this practice has not been evaluated in a southern climate. Two sites within the Blackbelt region of Alabama were evaluated for response to Fe‐EDDHA, Fe‐Citrate, and FeSO4 for their effect on yield and chlorosis in 2010, 2011, and 2012. Treatments were applied in‐furrow at planting, as a foliar spray at the V3 growth stage, or as a split‐application. Remote sensing, relative chlorophyll meter readings, and visual chlorosis scores (VCS) were assessed as methods for identifying degree of Fe chlorosis. At the location where IDC was most pronounced, all treatments of Fe‐EDDHA were effective at reducing VCS ratings when applied in‐furrow at planting; however, chlorosis evaluation through remote sensing and relative chlorophyll readings was not able to detect improvements in chlorosis measured with VCS. Treatments of Fe‐EDDHA at 4.5 kg product ha−1 increased yield whether applied as an in‐furrow at planting treatment or as a split application at planting and at V3 growth stage as a foliar spray. Treatments of Fe‐Citrate and FeSO4 did not improve yield as applied in this study. Results suggest that Fe‐EDDHA can be used in southern climates as a strategy to overcome IDC yield limitations.

Evaluation of soybean (Glycine max) germplasm for some important morphological traits using multivariate analysis

Based on the results obtained in present study, it is advocated that the genotypes namely MACS 1201, SL 788 and MASU 449 were identified as the best genotypes for grain yield. The cluster VII (CSB 08-09) and VI (SL 778, Dsb 20, MACS 1311, RKS 61, BAUS 40) was most diverse to each other. Hence, crossing between these cluster would help to accumulate favorable and desirable alleles for further improvement in grain yield and its component in soybean.

Combining ability analysis for yield and protein content in bread wheat (Triticum aestivum)

The experiment was conducted with 10 parents and their 45 F1s (half diallel) during crop seasons (2008/09 and 2009/10) under normal and heat-stress environment to find out combining ability effects. The analysis of variance showed highly significant differences for all the traits at genotypic level under both normal and heat-stress environment. The significant additive variance (D) and dominance variance (H1) indicated that, expression of these traits is controlled by both additive and non-additive gene action. Among the parents, there was asymmetrical distribution of positive and negative dominant genes and preponderance of over-dominance gene action for all the traits under both the environment. Estimates of narrow-sense heritability were higher for days to 50% flowering; days to maturity; plant height and spike length. Our results also indicated that only three parents (HD 2285 for grain filling duration and thousand grains weight; PBW 373 for the days to maturity and plant height and UP 2425 for number of tillers and grain yield) had favorable general combining ability (GCA) effects under normal sown environment. While under heat-stress environment, cultivar HD 2285 showed highest GCA effect for days to 50% flowering, grain filling duration and thousand grain weight; HD 2733 for plant height and protein content; and PBW 373 for number of tillers and grain yield. Five cross combinations showed contrasting favorable specific combining ability (SCA) effect for more than one trait under both normal and heat-stress environment. Attempting combinations involving parents with high GCA for desirable yield components could be useful. The traits showing more than 35 percent narrow-sense heritability could be rewarding for further improvement of grain yield and protein content in wheat (Triticum aestivum L.).

Foliage applied boron improves the panicle fertility, yield and biofortification of fine grain aromatic rice

Boron (B) deficiency in rice field is becoming a common problem in South Asia. Correcting B deficiency in rice has potential to improve the rice productivity. Foliage application of B is an easy and effective way to resolve this problem. This study was conducted to evaluate the influence of foliage applied (0.16, 0.24, 0.32, 0.40 and 0.48 M) B on leaf elongation, tillering, water relations, yield and B grain enrichment of rice cultivars Super Basmati and Shaheen Basmati. Foliage applied B improved leaf elongation, tillering, leaf chlorophyll contents, water relations, grain yield, yield-related traits and B grain contents with simultaneous decrease in panicle sterility. However, foliage application of 0.32 M B was the most effective in this regard. An increase in leaf and grain B contents was observed with increase in B concentration in the foliar spray. There was no difference between the cultivars for grain yield; however, Shaheen Basmati had more grain weight, and grain and leaf B contents than Super Basmati. Boron foliage application (0.32 M B) proved an effective way to correct B deficiency in rice. Improvement in grain yield by B application was attributed to increase in grain size and decrease in panicle sterility.