Yield Per Plant Research Articles

Determination of Combinatorial Ability and Heterosis in Capsicum chinense Jacq., using Line × Tester Analysis Method

Objective: Know the combinatory ability and heterosis in yield parameters and fruit quality, in nine genotypes of Habanero Chilli (Capsicum chinense Jacq.). Design/methodology/approach: In order to know the combinatory ability and heterosis in yield parameters and fruit quality, were crossed nine genotypes of Capsicum c hinense Jacq. (Habanero Chilli) in a Line × Tester (7 × 2) mating design. The parental lines and combination of crosses were evaluated in a randomized complete block design with three replications at the Yucatan Scientific Research Center during the 2018 and 2019. Results: The results showed the lines 3 and 7, presented a high and positive general combinatory ability (GCA) for most of the parameters studied, the tester 1 presented a high GCA for yield per plant (YP) with 0.45. The cross L1 × T2 presented the highest value of specific combining ability (SCA) for YP with 0.50. The highest heterosis (171.01%) was observed in the L1 × T1 cross for capsaicin content (CC). Tester 1 was identified as a promising genotype for breeding Capsicum chinense Jacq. Findings/conclusions: Line 7 and Tester 1 was identified as promising genotypes for crop breeding Capsicum chinense Jacq.

Validation of SSR markers for identification of high-yielding and Phytophthora Capsici root rot resistant chilli genotypes

The study was designed to validate the previously reported 34 SSR markers using 78 chilli genotypes to detect significant trait specific markers as well as superior genotypes resistant to Phytophthora capsici root rot (PcRR). In this context, the identification of germplasm with higher yield per plant (YPP) leads to hype in stress tolerance index (STI) in genotypes, Chakwal3 (11.98), Greenfire (10.14), Advanta5017 (9.94) and Chakwal4 (7.8). The identified genotypes were also found as resistant and moderately resistant due to existence of below 50% of disease incidence. Moreover, biplot showed the interrelation of STI with YPP through the formation of acute angle by their respective vectors. In the current study, the markers Hpms1172 and CAMS177 was found significant for STI. However, the marker CAMS066 was found associated with relative cell injury, CA06g27450 with disease incidence and CAMS173 with relative leaf damage. The bright bands on gel pictures of significant markers showed the association of these markers with resistant genotypes i.e. Chakwal3, Advanta-5017 and Chakwal4 as well as with a single moderately resistant genotype i.e. Greenfire. The markerstudes confirmed the phenotypic data by showing association of markers i.e. Hpms1172 and CAMS177, r with stress tolerance index. The principal coordinate analysis aligned with the results obtained from marker-assisted selection. Thus, currently practiced marker assisted selection detected high yielding genotypes in PcRR disease stress condition that will be helpful in progressing breeding programs in chilli.

CRISPR–Cas9-mediated promoter editing of FERONIA-Like receptor 13 increases plant growth and disease resistance in rice

Receptor kinases play a pivotal role in detecting environmental signals, and consequently, gene pleiotropy is frequently observed within this family. However, the trade-off in trait expression resulting from gene pleiotropy poses a constraint on the utilization of such genes in agricultural breeding. In this study, we identified the receptor kinase gene FERONIA-Like Receptor 13 (FLR13) as a pleiotropic gene influencing plant height, tillering, grain yield, and disease resistance. Using promoter editing, we generated novel alleles (FLR13T5T6-1, FLR13T5T6-2) that confer resistance to rice blast and increase per-plant yield. The knockout of the T5T6 segment alleviates the inhibitory effects of two transcription factors, OsGBP1 and OsWRKY53, on FLR13 expression. In summary, our study presents a promising avenue for enhancing the pivotal attributes of receptor-like kinases through a promoter-editing strategy.

Multivariate Analysis of Grain Yield and Main Agronomic Traits in Different Maize Hybrids Grown in Mountainous Areas

Inconsistent reports exist on the relationships between key agronomic traits and maize yield. We performed a multivariate analysis of yield and 10 agronomic traits in 59 hybrids to explore maize yields in mountainous areas. The yield per plant (YP) was significantly and positively correlated with kernel weight (KW), growth period (GP), and kernel row number (KRN). KW and KRN had positive effects on YP, whereas kernel rows per ear (KRE) had a negative effect. GP indirectly affected YP. GP, KW, KRN, and ear length (EL) showed the highest grey relational degree with YP. The first four principal components cumulatively accounted for 73.36% of variation. EL, KW, plant height (PH), ear height (EH), GP, KRN, and YP contributed positively to the variation, whereas KRE, shelling percentage (SP), bald-tip length (BTL), and ear girth (EG) contributed negatively. Based on trait similarity, the 59 maize hybrids were classified into two clusters, Clusters I and II. A total of 11 traits were grouped into four clusters, Clusters A–D. Cluster D included KW, GP, KRN, EL, EH, PH, and YP, and the 22 maize hybrids in Cluster I performed better in these traits. These results provide a theoretical basis for the breeding of high-yield maize varieties in mountainous areas.

Construction of high-density genetic map based on SLAF-seq and QTL analysis of major traits in sweetpotato [Ipomoea batatas (L.) Lam.]

Sweetpotato, Ipomoea batatas (L.) Lam., is an important worldwide crop used as feed, food, and fuel. However, its polyploidy, high heterozygosity and self-incompatibility makes it difficult to study its genetics and genomics. Longest vine length (LVL), yield per plant (YPP), dry matter content (DMC), starch content (SC), soluble sugar content (SSC), and carotenoid content (CC) are some of the major agronomic traits being used to evaluate sweetpotato. However limited research has actually examined how these traits are inherited. Therefore, after selecting 212 F1 from a Xin24 × Yushu10 crossing as the mapping population, this study applied specific-locus amplified fragment sequencing (SLAF-seq), at an average sequencing depth of 26.73 × (parents) and 52.25 × (progeny), to detect single nucleotide polymorphisms (SNPs). This approach generated an integrated genetic map of length 2441.56 cM and a mean distance of 0.51 cM between adjacent markers, encompassing 15 linkage groups (LGs). Based on the linkage map, 26 quantitative trait loci (QTLs), comprising six QTLs for LVL, six QTLs for YPP, ten QTLs for DMC, one QTL for SC, one QTL for SSC, and two QTLs for CC, were identified. Each of these QTLs explained 6.3–10% of the phenotypic variation. It is expected that the findings will be of benefit for marker-assisted breeding and gene cloning of sweetpotato.

Effect of organic manure and biofertilizers on growth and yield of Dill (Anethum graveolens L.)

A field experiment was conducted during the Rabi season of 2020-21 tostudy the effect of organic manure and biofertilizers on growth and yield ofdill (Anethum graveolens L.). The eight treatment combinations of FYM,vermicompost and biofertilizers were tested in randomized block designwith three replications. Result indicated that organic manure andBiofertilizers significantly influenced growth and yield of dill. Significantly-1 -1highest biological yield (42.67 q ha )and seed yield (1.57 q ha ) with-harvest index (46.14%) were observed under treatment T7 [FYM (5 tonha1 -1 -1 -1) + Vermicompost (2 ton ha ) + Azotobacter (3 kg ha ) + PSB (5 kg ha )]compared to control. Findings suggested that application of biologicalfertilizers significantly increased seeds performance, biological yield perplant, plant height, fresh weight, dry weight, number of umbels per plant,number of seeds per umbel.

Correlation and Path Coefficient Analyses for Grain Yield and Its Contributing Traits in Bread Wheat (Triticum aestivum L. em. Thell)

The study on bread wheat for fourteen characters viz., days to heading (50%), days to maturity, plant height (cm), number of productive tillers per plant, chlorophyll content , spike length (cm), number of spikelets per spike, number of grains per spike, weight of grain per spike(g), 1000 grain weight (g), biological yield (g), harvest index (%),protein content (%) and grain yield per plant (g) was conducted by making crosses among ten diverse genotypes in half diallel fashion grown in Randomized Block Design in three replication during Rabi 2022-2023 at SIF, C. S. Azad University of Agriculture & Technology, Kanpur, U.P. to assess the correlation and path coefficient. At genotypic level grain yield per plant showed positive and significant correlation with biological yieldper plant followed by number f productive tillers per plant, weight of grain per spike, harvest index, 1000 grain weight, chlorophyll content and days to maturity. In F2 generation correlation coefficients at genotypic level higher than the corresponding phenotype correlation coefficient for all characters and eight characters viz., biologic yield per plant, weight of grain per spike, number of productive tillers per plant, harvest index, 1000 grain weight, days to maturity, protein content and number of grain per spike showed positive and significant correlation with grain yield per plant. At genotypic level the highest positive direct effect on grain yield per plant was exerted by biological yield per plant followed by harvest index, number of spikelets per spike, spike length, days to 50% heading, 1000 grain weight, number of productive tiller per plant, weight of grain per spike, chlorophyll content and protein content in F1s.At phenotypic level the highest positive direct effect on grain yield per plant was exerted by biological yield per plant followed by harvest index, spike length, days to maturity, number of productive tiller per plant, weight of grain per spike, chlorophyll contend and protein content in F2s. Hence these characters may be considered for selection and improvement of grain yield in bread wheat.

Genetic dissection of advanced soybean (Glycine max L.) germplasm for spring season cultivation in Pakistan

AbstractImprovement in genetic gains of crops could be achieved by phenomics' characterization of agronomic, physiological and stress-related traits. Molecular and strategic breeding programmes require broad range of foreground and background phenotypic information for crop improvement. The current experiment was performed on 123 advanced soybean (Glycine max L.) genotypes including seven local lines belongs to four different maturity groups (000-lV) to estimate the endogenous potential of various yield-related traits. The experimental trial was repeated for two cropping seasons. Four traits out of six, yield per plant (YPP), number of seeds per plant, number of pods per plant and plant height (PH), showed maximum variation (CV%) that directly correlate with variability in the subjected population. PH, number of pods, 100-seed weight and YPP showed strong positive correlation in both years. Among the principal components, factors 1 and 2 showed maximum contribution in phenotypic variability ranges from 19 to 48.5% and 26 to 47.7% in the first and second years, respectively. Number of pods showed significant positive correlation with genotypes in both years. Dendrogram showed two distinct groups of soybean genotypes. Genetic variation and association among the accessions is indispensable for effective conservation and utilization of germplasm. Principal component analysis helps to identify the diverse genotypes that will be used as a parent for various breeding programmes. These phenotypic data will be used for detection of heat stress-related quantitative trait loci with genotypic data in genome-wide association studies experiments.

Fine mapping of a major QTL, qKl-1BL controlling kernel length in common wheat.

A major stable QTL, qKl-1BL, for kernel length of wheat was narrowed down to a 2.04-Mb interval on chromosome 1BL; the candidate genes were predicated and the genetic effects on yield-related traits were characterized. As a key factor influencing kernel weight, wheat kernel shape is closely related to yield formation, and in turn affects both wheat processing quality and market value. Fine mapping of the major quantitative trait loci (QTL) for kernel shape could provide genetic resources and a theoretical basis for the genetic improvement of wheat yield-related traits. In this study, a major QTL for kernel length (KL) on 1BL, named qKl-1BL, was identified from the recombinant inbred lines (RIL) in multiple environments based on the genetic map and physical map, with 4.76-21.15% of the phenotypic variation explained. To fine map qKl-1BL, the map-based cloning strategy was used. By using developed InDel markers, the near-isogenic line (NIL) pairs and eight key recombinants were identified from a segregating population containing 3621 individualsderived from residual heterozygous lines (RHLs)self-crossing. In combination with phenotype identification, qKl-1BL was finely positioned into a 2.04-Mb interval, KN1B:698.15-700.19Mb, with eight differentially expressed genes enriched at the key period of kernel elongation. Based on transcriptome analysis and functional annotation information, two candidate genes for qKl-1BL controlling kernel elongation were identified. Additionally, genetic effect analysis showed that the superior allele of qKl-1BL from Jing411 could increase KL, thousand kernel weight (TKW), and yield per plant (YPP) significantly, as well as kernel bulk density and stability time. Taken together, this study identified a QTL interval for controlling kernel length with two possible candidate genes, whichprovides an important basis for qKl-1BL cloning, functional analysis, and application in molecular breeding programs.

The Phenotypic Diversity of 232 Germplasm Accessions Identifies the Adverse Effects of Flowering Redundancy on Peanut Yield

Peanut is a leguminous crop with an indeterminate growth habit that will continuously flower during the entire reproductive development stage. Flowering redundancy adversely affects the yield and quality of peanut. In this study, eight flowering and five yield-related traits were collected and comprehensively evaluated from a diverse germplasm panel consisting of 232 peanut accessions, aiming to provide a theoretical basis for improving the flowering habit and yield for future peanut breeding efforts. As a result, large phenotypic diversity was observed in 13 traits. Most of the traits suggested high heritability, except high effective flowering duration (HEFD), days to 100% flower cessation (DTC100), and yield per plant (YPP). Days to 90% flower cessation (DTC90), days to DTC100, flowering duration (FD), and low effective flowering duration (LEFD) showed significant negative correlations with 100-seed weight, 100-pod weight, YPP, average weight per pod, and shelling percentage. Principal component analysis (PCA) suggested that flowering redundancy traits as well as yield-related traits contributed more to the first three PCs when compared to other traits. This study addresses the lack of peanut flowering phenotypic and genetic diversity and lays the foundation for in-depth research on redundancy-related genes in peanut flowering.

Study on the genetic variability and adaptability of turmeric (Curcuma longa L.) genotypes for development of desirable cultivars.

Turmeric, a globally cultivated spice, holds significance in medicine, and cosmetics, and is also a very popular ingredient in South Asian cuisine. A study involving 53 turmeric genotypes evaluated for rhizome yield and related traits at Spices Research Center, Bogura, Bangladesh over three years (2019-22). A randomized complete block design was followed with two replications. ANOVA revealed significant trait variations among genotypes. Genotype T0015 emerged as the highest yielder at 28.04 t/ha. High heritability (0.58-0.99) and genetic advance characterized plant height (PH), mother rhizome weight (WMR), primary and secondary finger weights (WPF and WSF), and yield per plant (YPP) across seasons. Genetic gain (GG) was prominent in these traits. Genotypic and phenotypic coefficient variations (GCV and PCV) (6.24-89.46 and 8.18-90.88, respectively) across three years highlighted mother rhizome weight's importance followed by numbers of primary finger (NPF), and WPF. Positive and significant correlations, especially with PH, WMR, WPF, and YPP, emphasized their relevance to fresh yield (FY). Multiple linear regression identified PH, number of mother rhizome (NMR) and WMR as key contributors, explaining 37-79% of FY variability. Cluster analysis grouped genotypes into five clusters with maximum distance observed between clusters II and III. The geometric adaptability index (GAI) assessed adaptability and superiority, revealing nine genotypes outperforming the best existing cultivar. Genotype T0117 as the top performer based on GAI, followed by T0103 and T0094. Mean rank analysis favoured T0121 as the best performer, succeeded by T0117, T0082 and T0106. The top ten genotypes (T0015, T0061, T0082, T0085, T0094, T0103, T0106, T0117, T0121 and T0129) were identified as superior based on yield and overall ranking, warranting further evaluation. These findings may induce a window for improving turmeric research and ultimately play a role in enhancing its cultivation and productivity.

Combining Ability Studies of Promising Restorer Lines for Yield and Yield Components in Rice (Oryza sativa L.)

Background: The present inquisition was carried out at Regional Agricultural Research Station, Maruteru with a set of 30 experimental hybrids developed by crossing three male sterile lines with 10 testers in Line ´ Tester mating design during Kharif, 2022. Methods:The resultant 30 hybrids were studied in randomized block design with two replications along with the parents and hybrid check, HRI-174 during Rabi, 2022-23. Predominant non-additive gene action was found in the analysis of combining ability for lines, testers and line testers for grain production per plant, days to 50% flowering, days to maturity, ear bearing tillers per plant, filled grains per panicle and 1000-grain weight. Result:The results revealed RGL 5613 and MTU 2055 to be effective combiners for grain yield per plant, filled grains per panicle, spikelet fertility percentage and grain weight of one thousand grains. For five hybrids, the sca effects on grain yield per plant were large and favourable. These hybrids had recorded significantly higher grain yield perplant, more than 30 per cent, compared to the check, HRI-174, in addition to significant desirable sca effects for grain yield per plant.

Evaluation of rice (Oryza sativa L.) genotypes for low phosphorus stress tolerance

Phosphorus (P) deficiency is a prime factor limiting rice growth and yield around the globe. Understanding how plants respond to P starvation is very important for breeding varieties with enhanced P uptake and use efficiency. To assess the effect of low P stress on yield and yield contributing traits, an experiment was conducted using six rice genotypes applying two treatments (optimum and deficient P conditions). Data on yield and yield attributing traits viz., days to first flowering (DFF), days to maturity (DM), plant height (PH), number of total tillers/plant (NTTP), number of effective tillers/plant (NETP), panicle length (PL), 100-seed weight (100-SW) and yield per plant (YPP) were recorded. Analysis of variance showed highly significant variation among the genotypes (G), treatments (T) and G × T interaction. When compared with control, a significant reduction in yield and yield attributing traits was observed in most of the studied genotypes in response to low P stress. The highest reduction in YPP was recorded in BRRI dhan78 whereas the lowest reduction was observed in Binadhan-17. Principal component analysis revealed that the first three principal components explained 85.2% of the total variation. Yield per plant (g) showed significant positive correlation with PH, PL, NTTP and NETP whereas it showed significant negative correlation with DFF, DM and 100-SW. Based on stress tolerance indices Binadhan-17, BRRI dhan71 and BRRI dhan79 were categorized as tolerant genotypes and selected for cultivation in P deficient areas and are recommended for the genetic improvement of low P stress tolerance in rice.

Combining Ability Analysis of Yield-Related Traits of Two Elite Rice Restorer Lines in Chinese Hybrid Rice.

Hybrid rice breeding is an important strategy for enhancing grain yield. Breeding high-performance parental lines and identifying combining abilities is a top priority for hybrid breeding. Yuenongsimiao (YNSM) and its derivative variety Yuehesimiao (YHSM) are elite restorer lines with a high ability of fertility restoration, from which 67 derived hybrid combinations have been authorized to different degrees in more than 110 instances in China. In this study, we found that YNSM and YHSM contained three candidate restorer-of-fertility (Rf) genes, Rf3, Rf4, and Rf5/Rf1a, that might confer their restoration ability. Subsequently, we investigated heterosis and combining ability of YNSM and YHSM using 50 F1 hybrids from a 5 × 10 incomplete diallelic mating design. Our results indicated that hybrid combinations exhibited significant genetic differences, and the additive effects of the parental genes played a preponderant role in the inheritance of observed traits. The metrics of plant height (PH), 1000-grain weight (TGW), panicle length (PL), and the number of spikelets per panicle (NSP) were mainly affected by genetic inheritance with higher heritability. Notably, the general combining ability (GCA) of YHSM exhibited the largest positive effect on the number of grains per panicle (NGP), NSP, PL, and TGW. Thus, YHSM had the largest GCA effect on yield per plant (YPP). In addition, the GCA of YNSM exhibited a positive impact on YPP, mainly due to the critical contribution of seed setting percentage (SSP). Moreover, YNSM and YHSM exhibited negative GCA effects on PH, implying that YNSM and YHSM could effectively enhance plant lodging resistance by reducing the plant height of the derived hybrids. Remarkably, among the hybrids, Yuanxiang A/YNSM (YXA/YNSM), Shen 08S/Yuemeizhan (S08S/YMZ), and Quan 9311A/YHSM (Q9311A/YHSM) represent promising new combinations with a higher specific combining ability (SCA) effect value on YPP with a value more than 3.50. Our research thus highlights the promising application for the rational utilization of YNSM and YHSM in hybrid rice breeding.

Integrated multi-locus genome-wide association studies and transcriptome analysis for seed yield and yield-related traits in Brassica napus.

Rapeseed (Brassica napus L.), the third largest oil crop, is an important source of vegetable oil and biofuel for the world. Although the breeding and yield has been improved, rapeseed still has the lowest yield compared with other major crops. Thus, increasing rapeseed yield is essential for the high demand of vegetable oil and high-quality protein for live stocks. Silique number per plant (SN), seed per pod (SP), and 1000-seed weight (SW) are the three important factors for seed yield in rapeseed. Some yield-related traits, including plant height (PH), flowering time (FT), primary branch number (BN) and silique number per inflorescence (SI) also affect the yield per plant (YP). Using six multi-locus genome-wide association study (ML-GWAS) approaches, a total of 908 yield-related quantitative trait nucleotides (QTNs) were identified in a panel consisting of 403 rapeseed core accessions based on whole-genome sequencing. Integration of ML-GWAS with transcriptome analysis, 79 candidate genes, including BnaA09g39790D (RNA helicase), BnaA09g39950D (Lipase) and BnaC09g25980D (SWEET7), were further identified and twelve genes were validated by qRT-PCRs to affect the SW or SP in rapeseed. The distribution of superior alleles from nineteen stable QTNs in 20 elite rapeseed accessions suggested that the high-yielding accessions contained more superior alleles. These results would contribute to a further understanding of the genetic basis of yield-related traits and could be used for crop improvement in B. napus.

Study of genetic variability, heritability, and genetic advance for yield-related traits in tomato (Solanum lycopersicon MILL.).

Tomato is one of the most significant vegetable crops, which provides several important dietary components. Pakistan has a significant low tomato yield compared to other countries because of low genetic diversity and the absence of improved cultivars. The present study aimed to investigate the genetic variability, heritability, and genetic advance for yield and yield-related traits in tomato. For this purpose, eight tomato parents and their 15 crosses or hybrids were evaluated to study the relevant traits. Significant variation was observed for all studied traits. Higher values of the genotypic coefficient of variability (GCV) and phenotypic coefficient of variability (PCV) were recorded for yield per plant (YP) (kg) (37.62% and 37.79%), as well as the number of fruits per cluster (NFRC) (31.52% and 31.71%), number of flowers per cluster (24.63 and 24.67), and single fruit weight (g) (23.49 and 23.53), which indicated that the selection for these traits would be fruitful. Higher heritability (h2) estimates were observed for the number of flowers per cluster (NFC) (0.99%), single fruit weight (SFW) (g) (0.99%), and yield per plant (YP) (kg) (0.99%). Single fruit weight (SFW) (g) exhibited higher values for all components of variability. High genetic advance as a % of the mean (GAM) coupled with higher heritability (h2) was noted for the yield per plant (YP) (kg) (52.58%) and the number of fruits per cluster (NFRC) (43.91). NFRC and SFW (g) had a highly significant correlation with YP (kg), while FSPC had a significant positive association with YP (kg), and these traits can be selected to enhance YP (kg). Among the 15 hybrids, Nagina × Continental, Pakit × Continental, and Roma × BSX-935 were selected as high-yielding hybrids for further evaluation and analysis. These findings revealed that the best performing hybrids could be used to enhance seed production and to develop high-yielding varieties. The parents could be further tested to develop hybrids suitable for changing climatic conditions. The selection of YP (kg), SFW (g), NFC, and NFRC would be ideal for selecting the best hybrids.

VARIATION OF GROWTH AND YIELD OF CHILLI WITH DIFFERENT DOSES OF NITROGEN IN LAMJUNG DISTRICT, NEPAL

The study was undertaken to assess how the growth and yield of the NS-1701 chili variety were impacted by different nitrogen doses in the Lamjung district’s Rainas area. The study involved arranging five different treatment combinations within a Randomized Complete Block Design (RCBD), with each combination being replicated four times. The application consisted of doses (0 kilograms per hectare, 30 kilograms per hectare, 60 kilograms per hectare, 90 kilograms per hectare, 120 kilograms per hectare). Various parameters related to plant growth and yield were observed throughout the study timeframe. The data underwent statistical analysis utilizing Microsoft Excel and R-studio software. Duncan’s Multiple Range Test (DMRT) was applied to distinguish means at a significance level of 5% for the purpose of separation. Growth characteristics such as plant height and the quantity of branches, along with yield-related attributes like fruit length, number of fruits per plant, individual plant weight, and yield (tons per hectare), displayed noteworthy variations until the point of harvest. Among varying nitrogen quantities, the most pronounced plant height (82.40 cm), branch count (8.38), fruit length (11.41 cm), fruits per plant (116.55), per-plant yield (475.5 gm), and overall yield (31.70 t/ha) were achieved with the application of 120 kilograms of nitrogen per hectare. Across all characteristics studied, the analysis of variance (ANOVA) indicated a noteworthy disparity between the various nitrogen doses concerning both yield and growth parameters. Among the range of nitrogen doses tested, the utilization of 120 kilograms of nitrogen per hectare resulted in enhanced growth and yield characteristics. This outcome could be proposed as a beneficial approach for cultivating chili in both the Lamjung district and comparable agro-ecological circumstances.

QTL for yield per plant under water deficit and well-watered conditions and drought susceptibility index in soybean (Glycine max (L.) Merr.)

Drought has historically represented the greatest abiotic stress to adversely affect the stability of soybean (Glycine max (L.) Merr.) yields in non-irrigated field conditions. To investigate the genetic basis underlying drought tolerance in soybean, we screened the seed yield per plant (YP) in a natural diversity panel of 149 accessions under both water deficit (drought-stressed; YP-S) and well-watered (full irrigation; YP-W) conditions in field and greenhouse trials and calculated a drought susceptibility index (DSI) based on the differences in yield between treatments within each accession. A total of 19 quantitative trait loci (QTLs) were identified: eight were significantly associated with YP-W, 10 were associated with YP-S, 2 were associated with DSI and one QTL was associated with both YP-S and DSI. We then compared QTLs identified here with previously reported markers and found that these loci were located in regions associated with yield-related and other agronomic traits. In particular, YP-S-associated single nucleotide polymorphism (SNP) ss246509299 in chromosome (Chr.) 8, and YP-W-associated ss249310678 on Chr. 17 were both previously correlated with canopy wilt. Eight significant QTLs were located within eight genes. Glyma.18g092200, contained ss249600231 and annotated as GmWRKY168, is reportedly responsive to cadmium. This study helps to resolve which loci contribute to yield under drought stress in soybean, and can potentially serve as markers for selection of elite, high-yield and drought tolerant varieties.

Individual and Combined Effects of High-Temperature Stress at Booting and Flowering Stages on Rice Grain Yield

Extreme temperature events as a consequence of global climate change result in a significant decline in rice yield. A two year phytotron experiment was conducted using three temperature levels and two heating durations to compare the effects of heat stress at booting (BT), flowering (FL), and combined (BT + FL) stages on rice yield and yield components. Compared with T1 (Tmean of 27 °C), heat stress at BT + FL and BT stages produced more regenerated tillers and compensated more for yield loss than heat stress at FL. Heat stress at BT + FL stages alleviated spikelet sterility and yield loss of original tillers compared to heat stress at FL. The greater variation of yield per plant (YPP) under heat stress at flowering as compared to BT and BT + FL stages was accompanied by a higher decrease in spikelet fertility, while, at BT and BT + FL stages, spikelet number per plant and 1000-grain weight also contributed well to variation in yield. Furthermore, heat stress during BT and BT + FL stages caused a significant decline in spikelet fertility of the upper part of panicles, followed by middle and lower parts, while heat stress at the FL stage responded inversely. For every 1 °C day increase in heat degree days at BT, FL, and BT + FL stages, YPPO (only original tillers) declined by 2.9%, 2.5%, and 6.0%, and YPPT (including original + regenerated tillers) decreased by 5.8%, 2.7%, and 2.2%, respectively. The projected alleviation effects under BT + FL stages of heat stress in contrast to single-stage heat stress would help to accurately estimate rice yield under extreme temperature events, as well as to develop a heat-tolerant rice cultivar.

Optimized Phosphorus Application Alleviated Adverse Effects of Short-Term Low-Temperature Stress in Winter Wheat by Enhancing Photosynthesis and Improved Accumulation and Partitioning of Dry Matter

Low-temperature stress has become an important abiotic factor affecting high and stable wheat production. Therefore, it is necessary to take appropriate measures to enhance low-temperature tolerance in wheat. A pot experiment was carried out using Yannong19 (YN19, a cold-tolerant cultivar) and Xinmai26 (XM26, a cold-sensitive cultivar). We employed traditional phosphorus application (TPA, i.e., R1) and optimized phosphorus application (OPA, i.e., R2) methods. Plants undertook chilling (T1 at 4 °C) and freezing treatment (T2 at −4 °C) as well as ambient temperature (CK at 11 °C) during the anther differentiation period to investigate the effects of OPA and TPA on photosynthetic parameters and the accumulation and distribution of dry matter. The net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of flag leaves decreased in low-temperature treatments, whereas intercellular carbon dioxide concentration (Ci) increased. Compared with R1CK, Pn in R1T1 and R1T2 treatments was reduced by 26.8% and 42.2% in YN19 and 34.2% and 54.7% in XM26, respectively. In contrast, it increased by 6.5%, 8.9% and 12.7% in YN19 and 7.7%, 15.6% and 22.6% in XM26 for R2CK, R2T1 and R2T2 treatments, respectively, under OPA compared with TPA at the same temperature treatments. Moreover, low-temperature stress reduced dry matter accumulation at the reproductive growth stage. OPA increased dry matter accumulation of vegetative organs after the flowering stage and promoted the transportation of assimilates to grains. Hence, the grain number per spike (GNPS), 1000-grain weight (TGW) and yield per plant (YPP) increased. The low-temperature treatments of T1 and T2 caused yield losses of 24.1~64.1%, and the yield increased by 8.6~20.5% under OPA treatments among the two wheat cultivars. In brief, OPA enhances low-temperature tolerance in wheat, effectively improves wheat architecture and photosynthesis, increases GNPS and TGW and ultimately lessens yield losses.