Total Number Of Spikelets Research Articles

Diallel analysis of yield and its important components in wheat (Triticum aestivum L)

This study was carried out in Andro Research Farm, CAU, Imphal to study diallel analysis of yield and its important components in 10 genotype of wheat during two consecutive rabi season 2017-2019. All the 10 genotype and their 45 F1’s cross combination exhibited significant difference in characters under study Combining ability analysis showed that both gca and sca variances value were highly significant for most of traits studied in F1 progenies which suggest importance of both additive as well as non-additive genetic components for the expression of characters under study. VL 3017 was found good general combiner for the characters like fifty percent flowering, days to eighty percent maturity, plant height, total number of tillers per hill, total number of spikelets per spike, spike length, total number of filled grains per spike and grain yield per plant. Among all 45 crosses, cross combination VL 3018 x HS 490 and VL 892 x UP 3017 were good specific combiners for the grain yield per plant character in F1 generation.

Genetic variability, heritability, genetic advance and phylogenetic relationship between rice tungro virus resistant and susceptible genotypes revealed by morphological traits and SSR markers

A study was conducted to assess the resistant sources, genetic variability and phylogenetic relationship among 44 rice genotypes based on pathogenicity, genetic parameters of morphological traits and simple sequence repeat markers. Results demonstrated that, 9 genotypes were resistant, 9 were moderately resistant and the rest of the genotypes were susceptible. The higher level of phenotypic coefficients of variation and genotypic coefficient of variation was found for number of tillers hill-1, number of panicle hill-1, number of filled grain panicle-1, number of unfilled grain panicle-1, total number of spikelets and yield hill-1. High heritability along with high genetic advance was observed for yield hill−1, number of filled grains panicle−1, 1000 grain weight hill–1 and total number of spikelets panicle−1 and these could be the desirable characters for selection. Polymorphic information content of SSR markers varied from 0.152 (RM161) to 0.760 (RM8213) with a mean value of 0.448. The higher PIC value (0.760) was obtained in RM8213 succeeded by RM3471 (0.719), RM279 (0.716), RM341 (0.689), RM336 (0.665), RM565 (0.664), RM287 (0.601) and RM562 (0.600), respectively which indicated that these markers are effective for the diversity evaluation of current genotypes. Cluster analysis of data matrix of 29 SSR markers, 44 genotypes divided into ten clusters. The results were also supplemented by principal component analysis. Between resistant and susceptible genotypes highest genetic distance was found between IR69705-1-1-1-4-3 and BR11 (0.14), IR69705-1-1-1-4-3 and BRRI dhan71 (0.14) followed by IR71605-3-1-1-2-6 and BRRI dhan49 (0.34), IR71605-3-1-1-2-6 and BR11 (0.38), Matatag 9 and BR11 (0.38), IR81244 (TW-16) and BR11, BRRI dhan39, BRRI dhan48 (0.41), IR71605-3-1-1-2-6 and BRRI dhan71 (0.41), IR81244 (TW-16) and BRRI dhan71 (0.45). Based on genetic distance and disease reaction data susceptible genotypes i.e. BR11, BRRI dhan39, BRRI dhan48 and BRRI dhan71 could be crossed with any of resistant genotypes IR69705-1-1-1-4-2, IR69705-1-1-1-4-3, IR71605-2-1-5-3-4, IR71605-3-1-1-2-6, IR81244 (TW-16), Matatag 9, Utri Merah-16680, Utri Merah-16682 and Utri rajapan to develop tungro resistant variety.

Locus determining 1000 grains weight at high temperatures (Russian rice varieties)

In Russia, increase in average air temperatures was noted in comparison with long-term data. Earlier it was shown that increase in average temperatures leads to a decrease in the productivity of plants for certain characteristics up to 90% and a yield of up to ten percent with an increase of 1 ° C. High temperatures above 30 ° C reduce the grain content, the total number and number of spikelets, weight grains from a plant, the mass of a thousand grains. A chromosomal region was established that reliably (at significance level 0.05) contributing to the formation trait mass of 1000 grains in domestic rice varieties in the region of localization of the RM 509 marker. A decrease significance level to 0.09 made it possible to identify another chromosome region with a possible localization of genes, determining the mass of 1000 grains at high temperatures. It is located in region of localization RM 13 marker. Four chromosomal regions have been identified that significantly contribute to the redistribution of plastic substances between grain and chaff under stress in domestic rice varieties on the first, fourth, ninth chromosomes (two loci) in the regions of localization of markers RM140, RM 261, RM 245, RM242 respectively.

Changes in starch quality of mid-season indica rice varieties in the lower reaches of the Yangtze River in last 80 years

Rice (Oryza sativa L.) quality depends mainly on the characteristics of starch stored in kernels. Understanding the changes in starch characteristics in kernels during variety improvement would have great significance to improve rice quality. This study was designed to investigate the starch characteristics in the kernels and associated physiological traits of indica rice varieties in the lower reaches of the Yangtze River in China in last 80 years. Eight representative mid-season indica rice varieties were grown in the field. The results showed that the grain yield was significantly increased with the improvement of varieties and such an increase was mainly attributed to the increase in total number of spikelets. The tall varieties applied in the 1940s–1950s had higher protein content, relative crystallinity and infrared (IR) ratio of 1 045/1 022 cm−1. The semi-dwarf varieties applied in the 1980s–1990s had higher gel consistency, amylopectin content, IR ratio of 1 022/995 cm−1, and breakdown value. With the improvement of varieties, the amylose content, large-sized starch granule number and volume distribution, onset and peak of gelatinization temperature, gelatinization and retrogradation enthalpy, setback value, pasting temperature, viscosity of peak, hot and final, and 1-aminocycopropane-1-carboxylic acid (ACC) concentrations in panicles and root bleeding were gradually decreased, whereas the medium-sized starch granule number and volume distribution, activities of key enzymes in grains, and zeatin (Z)+zeatin riboside (ZR) contents in panicles and root bleeding at grain filling stage were gradually increased. Correlation analysis showed that starch thermodynamic characteristics were closely related to starch structure and components, key enzymes and hormones. The results suggest that starch quality was enhanced through the optimization of starch components, structure, thermodynamics, and the regulation of key enzymes in grains and hormones in panicles and root bleedings at grain filling stage during the improvement of mid-season indica rice.

Effects of root morphology and physiology on the formation and regulation of large panicles in rice

Abstract At present, indica/japonica hybrid rice varieties of the Yongyou series generally show high yield and large panicles, but the physiological mechanism on the formation of large panicles is not clear. It is of great significance to understand the physiological mechanism and regulation of the formation of large panicles in super high-yield rice varieties. In this study, five groups of different rice varieties with significant differences in yield levels were selected as materials to study the contribution of large panicles to rice yield, the physiological changes in roots and canopy during the panicle differentiation stage and the regulation of large panicles by panicle nitrogen fertilizer under field and pot cultivation conditions. The results showed that 1. high-yield indica/japonica hybrid rice varieties were characterized by high spikelet number per panicle and high total number of spikelets. 2. The zeatin (Z) and zeatin riboside (ZR) contents in roots and panicles from spikelet primordium differentiation (SPD) to pistil and stamen formation (PSF), root activity (root dry weight, root oxidation activity, root bleeding rate, root total absorbing surface area and root active absorbing surface area) and non-structural carbohydrate (NSC) accumulation in stems from pollen mother cell meiosis (PMC) to pollen filling (PF) were very significantly and positively correlated with spikelet number per panicle. 3. Compared with 0 N (no panicle nitrogen fertilizer), the number of spikelets per panicle and total spikelets of Yangdao 6 and Yongyou 1540, the Z + ZR contents in panicles and roots during SPD-PSF, and the root activity and NSC accumulation in stems during PMC-PF were significantly improved under LN (panicle nitrogen fertilizer at a rate of 1.2 g pot-1) and MN (panicle nitrogen fertilizer at a rate of 2.4 g pot-1). High Z + ZR contents in young panicles and roots during SPD-PSF and large amounts of root activity (root dry weight, root oxidation activity, root bleeding rate, root total absorbing surface area and root active absorbing surface area) and NSC accumulation in stems during PMC-PF were important physiological factors in the formation of large panicles in super high-yield indica/japonica hybrid rice. Improvements in the above indexes during the panicle differentiation stage are likely contribute to the formation of large panicles and the increase in rice yield.

Mapping and characterization of major QTL for spike traits in common wheat.

The spike traits of wheat can directly affect yield. F2 and F2:3 lines derived from the cross of the multi-spikelet female 10-A and the uni-spikelet male BE89 were used to detect QTLs for spike length (SL), total spikelet number per spike (TSS), kernel number per spike (KNS) and thousand-kernel weight (TKW) in four different environments. A total of 1098 SNP and 5 SSR were used to construct genetic map of 2398.1cM with the average distance of 2.2cM between markers. A total of 11 QTLs were identified for spike traits, including three QTLs for SL, five QTLs for TSS, two QTLs for KNS and one QTL for TKW. The QTLs mapped to chromosomes 2D, 4A, 6A, 7A and 7B explained 8.2-37.8% of the phenotypic variation in single environment. The major QTL confidence interval with distance of 0.5cM was located on chromosome 4A and detected in multiple environments, which can explain more than 30% of the phenotypic variation for SL, TSS and KNS. Combining IWGSC RefSeq v1.0 and RNA-seq data for 10-A and BE89, we identified 16 genes expressed on spike or grain in four QTL regions. These findings provide insights into improving wheat yield through increasing spikletes in wheat, particularly through the use of the multi-spikelet female 10-A for breeding.

Effect of wide-narrow row arrangement in mechanical pot-seedling transplanting and plant density on yield formation and grain quality of japonica rice

Mechanical pot-seedling transplanting is an innovatively developed transplanting method that has the potential to replace mechanical carpet-seedling transplanting. However, the initial pot-seedling transplanting machine lacked optimized density spacing and limited yield potential for japonica rice. Therefore, ascertaining the optimized density by wide-narrow rows and the appropriate transplanting method for yield formation and grain quality of japonica rice is of great importance for high-quality rice production. Field experiments were conducted using two japonica rice cultivars Nanjing 9108 and Nanjing 5055 under three transplanting methods in 2016 and 2017: mechanical pot-seedling transplanting with wide-narrow row (K, average row spacing of 30 cm); equidistant row (D, 33 cmx12 cm); and mechanical carpet-seedling transplanting (T, 30 cm×12.4 cm). In addition, five different density treatments were set in K (K1–K5, from 18.62×104 to 28.49×104 hills ha–1). The results showed that the highest yield was produced by a planting density of 26.88×104 hills ha–1 in mechanical pot-seedling transplanting with wide-narrow row with a greater number of total spikelets that resulted from significantly more panicles per area and slightly more grain number per panicle, as compared with equidistant row, and yield among density in wide-narrow row showed a parabolic trend. Compared with mechanical carpet-seedling transplanting, the treatment of the highest yield increased yield significantly, which was mainly attributed to the larger sink size with improved filled-grain percentage and grain weight, higher harvest index, and increased total dry matter accumulation, especially the larger amount accumulated from heading stage to maturity stage. With the density in wide-narrow row decreasing, processing quality, appearance quality, and nutrition quality were all improved, whereas amylose content and the taste value were decreased. Compared with mechanical carpet-seedling transplanting, mechanical pot-seedling transplanting improved processing quality and nutrition quality, but decreased amylose content and deteriorated appearance quality. These results suggested that mechanical pot-seedling transplanting with wide-narrow row coupling produced a suitable planting density of 26.88×104 hills ha–1 and may be an alternative approach to improving grain yield and quality for japonica rice.

Comparative Study on Seed Production Potentiality of Selected Rice (Oryza sativa L.) Hybrid Combinations

The seed production potentialities of selected 20 hybrid rice combination were assessed in this study. Higher seed yield potentiality and earliness in maturity were two of the most important indicators for popularizing hybrid rice variety in Bangladesh. The field performance of the selected hybrid rice combinations were found to vary significantly for different traits except number of total spikelets per panicle showed insignificant variation among the hybrid rice genotypes. The highest number of tillers per plant was recorded in BRRI7A/BRRI31R (17.33) which was followed by BRRI10A/BRRI20R (16.33) and BRRI7A/BRRI20R (16.17). Maximum number of panicles per plant was produced by BRRI7A/BRRI31R (14.00) which was followed by BRRI10A/BRRI31R (13.07), and BRRI11A/BRRI31R (12.47). The highest number of filled spikelets per panicle was produced by BRRI7A/BRRI31R (48.20) which was followed by IR79156A/BRRI31R (47.83) and BRRI7A/BRRI10R (44.63) respectively. The highest value for percent out crossing rate (%OCR) was observed in the combination of BRRI7A/BRRI31R (50.23%) which was followed by BRRI10A/BRRI10R (46.40%). The highest value for grain yield per plant was recorded in BRRI7A/BRRI31R (8.17g) followed by BRRI10A/BRRI10R (7.85 g) and BRRI11A/BRRI15R (7.68 g), respectively. The lowest value for grain yield per plant was found in IR79156A/BRRI31R (3.97 g). Considering comparative study of floral traits, BRRI7A/BRRI31R hybrid rice combination has good commercial prospects but seed production potentiality under Bangladesh conditions needs to be estimated with fine tune.
 Bangladesh Rice j. 2019, 23(1): 13-20

Heterosis and parent–progeny relationships for silk extrusion dynamics and kernel number determination in maize: Nitrogen effects

AbstractMaize (Zea mays L.) ear‐related traits conducive to final kernel number per plant (KNP) are currently considered key determinants of kernel set under abiotic stress. Understanding of the variation between parental inbred lines and their hybrids is limited. The objective of this work was to analyze the genotypic variation between a set of inbred lines and some of their derived hybrids for (a) total number of spikelets per ear, (b) silk extrusion dynamics, (c) KNP, and (d) sources of loss in KNP (i.e., silk and kernel abortions) under high and limited N supply. In inbreds, variations in KNP were strongly explained by variations in silk extrusion rate (SER) and silk abortion. In contrast, hybrid KNP was explained by the number of spikelet per ear, exposed silks on Day 5 (ESD5), and extruded silks (TES), as well as silk extrusion per unit area (ESMAX). Heterosis across N levels was high for KNP, ESMAX, SER, kernel abortion, and ESD5. Strong parent–progeny relationships (r ≥ .69, P < .01) were computed for reproductive morphology traits (TES, total spikelets) at both N levels, whereas (a) KNP, sources of loss, and ESMAX were highly heritable exclusively under high N supply, and (b) ESD5 was a good predictor of hybrids KNP only at low N supply. Based on its high heterosis across environments and good parent–progeny relationship for KNP under N deficiency, ESD5 quantification should be part of breeding programs aimed to low‐N environments, depending upon the development of image‐based plant and crop phenotyping.

Differences in yield and nitrogen absorption and utilization of <italic>indica-japonica</italic> hybrid rice varieties of Yongyou series

<p indent=0mm>A field experiment was conducted with 24 <italic>indica-japonica</italic> hybrid rice varieties (lines) of Yongyou series, from which three types (high yield and high AE (agronomic nitrogen use efficiency) [HH], high yield and medium AE [HM], medium yield and medium AE [MM]) were selected to explore the characteristics of varieties with high yield and high AE. The yield of HH type was 4.04%–4.38% and 13.37%–13.41% higher than that of HM type and MM type respectively, owing to the larger number of total spikelets, which was 5.87×10⁸–6.20×10⁸ hm^–2. Compared with HM and MM type, HH type had a high percentage of tiller rate, which was 68.83%–70.05%. The LAI of HH type was maximum at heading stage and declined slowly after heading. As a result, the LAI of HH type was above 3.85 at maturity stage. The dry matter accumulation of HH type was <sc>7.91–7.99 t</sc> hm^–2 from heading to maturity, which was the highest in three types, and its dry matter accumulation was more than <sc>21.15–21.46 t</sc> hm^–2 in the whole growth period. The total nitrogen uptake of HH type showed 5.07%–5.14% and 4.50%–5.96% increase than that of HM type and MM type respectively at maturity stage. The nitrogen sbsorption rate from jointing to heading stage and from heading to maturity stage showed HH type > HM type > MM type, as well as NTSH (N transportation from stem after heading), NIPH (N increase in panicle after heading) and NHI (N harvest index). HH type had the highest NRE (nitrogen recovery use efficiency), AE, PE (physiological nitrogen use efficiency) and PFP (partial factor productivity of applied N). Expect for NRE and NRG (nitrogen requirement for <sc>100 kg</sc> grain), all the other nitrogen utilization indexes of HM type were higher than that of MM type.

Pleiotropic QTL influencing spikelet number and heading date in common wheat (Triticum aestivum L.).

Three pleiotropic QTL regions associated with spikelet number and heading date were identified, with FT-A1 considered the candidate gene for QTspn/Hd.cau-7A. Spikelet number traits and heading date (HD) play key roles in yield improvement of wheat and its wide adaptation to different environments. Here, we used a Recombinant Inbred Lines population derived from a cross between Yi5029 (5029) and Nongda4332 (4332) to construct a high-density genetic linkage map and identify quantitative trait loci (QTL) associated with total spikelet number per spike (TSPN), fertile spikelet number per spike (FSPN), sterile spikelet number per spike (SSPN) and HD. A total of 22 environmentally stable QTL for TSPN, FSPN, SSPN and HD were identified. Notably, three pleiotropic QTL regions for TSPN and HD were detected on chromosomes 2A, 7A and 7D. The QTL associated with TSPN and HD on chromosome 7AS was designated QTspn/Hd.cau-7A. Furthermore, the candidate gene FT-A1 located in the region of QTspn/Hd.cau-7A had a single-nucleotide polymorphism (T-G) within the third exon, which might be the cause of diversity in spikelet number and HD between the two parents. Additionally, we developed a semi-thermal asymmetric reverse PCR (STARP) marker to analyze the geographical distribution and evolution of FT-A1 (T or G) alleles. This study contributes to our understanding of the molecular mechanisms of the four traits (TSPN, FSPN, SSPN and HD) and provides further insights into the genetic relationship between spikelet number traits and HD in wheat.

GENETIC VARIABILITIES OF AGRONOMIC TRAITS AND BACTERIAL LEAF BLIGHT RESISTANCE OF HIGH YIELDING RICE VARIETIES

&lt;p class="abstrakinggris"&gt;Hundred of high yielding and bacterial leaf blight (&lt;em&gt;Xanthomonas oryzae&lt;/em&gt; pv. &lt;em&gt;oryzae, Xoo&lt;/em&gt;) resistant rice varieties released since the 1960s are important sources of genetic materials for exploring superior genotypes. The study aimed to evaluate the genetic resistance of 177 rice varieties to &lt;em&gt;Xoo&lt;/em&gt; and their agronomic traits. The evaluations were conducted at the Indonesian Center for Rice Research Experimental Station during the wet season (December 2015-March 2016). The bacterial leaf blight resistance was evaluated for &lt;em&gt;Xoo&lt;/em&gt; pathotypes III, IV, and VIII using the clipping method. The genetic variation among genotypes was categorized as low (0–10%), medium (10–20%), and high (&amp;gt;20%), whereas the heritability was categorized as low (0-30%), medium (30-60%), and high (&amp;gt;60%). The variability of resistance to &lt;em&gt;Xoo&lt;/em&gt; pathotypes, grain yield, and spikelet fertility was low, while the variability of plant height, productive tiller number, filled grain, and total spikelet was medium, and the variability of unfilled grain number was high. The 29 varieties were categorized as superior based on their agronomic traits or resistance to &lt;em&gt;Xoo&lt;/em&gt; pathotypes. In conclusion, Batutegi and Fatmawati were superior in the total spikelet number, while Rojolele and Inpari 2 were supreme in the thousand-grain weight. Dodokan had a very short maturity, and Inpari 24, Conde, Kalimas, Angke, Inpari 17, and Inpara 8 had the highest resistance to &lt;em&gt;Xoo&lt;/em&gt; pathotypes. The study implies that the identified rice superior genotypes could be used as genetic materials to design cross combinations for higher yield potential and BLB resistance varietal improvement.&lt;/p&gt;

Uji Daya Hasil Lanjutan Dua Puluh Tujuh Galur Padi Code-qTSN4 dan Code-qDTH8

ABSTRACT The locus that regulates total spikelet number (qTSN4) and days to heading (qDTH8) is expected to increase rice yields. Both of these loci are used to increase the yield of Code varieties through the marker-assisted backcrossing method. This study aimed to evaluate the yield of Code-qTSN4 and Code-qDTH8 lines at two location and to analyze existence of target gene locus associated with qTSN4, qDTH8, and Xa7. This research was conducted in March to July 2017. The study was divided into two parts: (i) field analyses at the Kuningan field station (uplandirrigated) and Sukamandi field station (lowland-irrigated), and (ii) molecular tests at the Molecular Biology Laboratory, ICABIOGRAD, Bogor. The material used were 27 crossing lines of Code-qTSN4 and Code-qDTH8 (BC1, BC2, BC3), 5 comparative varieties, and molecular markers that were linked to the loci of genes of qTSN4, qDTH8, and Xa7. The results showed different altitude positions affected the agronomic performance of the lines. At Kuningan location, Code-qTSN4 and Code-qDTH8 lines showed number of grain total (empty and filled) per panicle was 110.84−165.98 grains, while Code 153.51 grains. While at Sukamandi, the number of grains per panicle obtained by the lines was higher, that is 157.27-227.9 grains and 186.56 grains for Code. The highest number of total grains was achieved by line B6-2 (Code-qTSN4) (8.12%) for Kuningan, while at Sukamandi the highest was in line B22-1 (Code-qTSN4) (22.16%). The effect of the qTSN4 gene locus has been shown to increase the number of grains per panicle. The heading date of Code-qDTH8 lines at two locations was 4−6 days faster than Code. The yield potencial of lines at Kuningan and Sukamandi were 4.43−6.88 t/ha and 3.71−5.89 t / ha, while for Code 6.24 t/ha and 4.83 t/ha, respectively. The highest potential yield of Code-qTSN4 lines was B6-2 with an increase of 20.5%, while Code-qDTH8 lines was obtained on E13-1 with an increase 10.26%. Based on molecular analysis, all test lines already have the qTSN4 or qDTH8 gene locus, and all test lines also have the Xa7 gene locus. Keywords: Rice, Code, qTSN4, qDTH8, Xa7, yield trial

Uji Daya Hasil Lanjutan Dua Puluh Tujuh Galur Padi Code-qTSN4 dan Code-qDTH8

The locus thatregulates totalspikelet number (qTSN4) and days to heading (qDTH8) is expected to increase rice yields.Both of these loci are used to increase the yield of Code varieties through the marker-assisted backcrossing method. This study aimed to evaluate the yield of Code-qTSN4 and Code-qDTH8 lines at two location and to analyze existence of target gene locus associated with qTSN4, qDTH8, and Xa7. This research was conducted in March to July 2017. The study was divided into two parts: (i) field analyses at the Kuningan field station (uplandirrigated) and Sukamandi field station (lowland-irrigated), and (ii) molecular tests at the Molecular Biology Laboratory, ICABIOGRAD, Bogor. The material used were 27 crossing lines of Code-qTSN4 and Code-qDTH8 (BC1, BC2, BC3), 5 comparative varieties, and molecular markers that were linked to the loci of genes of qTSN4, qDTH8, and Xa7. The results showed different altitude positions affected the agronomic performance of the lines. At Kuningan location, Code-qTSN4 and Code-qDTH8 lines showed number of grain total (empty and filled) per panicle was 110.84−165.98 grains, while Code 153.51 grains. While at Sukamandi, the number of grains per panicle obtained by the lines was higher, that is 157.27-227.9 grains and 186.56 grains for Code. The highest number of total grains was achieved by line B6-2 (Code-qTSN4) (8.12%) for Kuningan, while at Sukamandi the highest was in line B22-1 (Code-qTSN4) (22.16%). The effect of the qTSN4 gene locus has been shown to increase the number of grains per panicle. The heading date of Code-qDTH8 lines at two locations was 4−6 days faster than Code. The yield potencial of lines at Kuningan and Sukamandi were 4.43−6.88 t/ha and 3.71−5.89 t / ha, while for Code 6.24 t/ha and 4.83 t/ha, respectively. The highest potential yield of Code-qTSN4 lines was B6-2 with an increase of 20.5%, while Code-qDTH8 lines was obtained on E13-1 with an increase 10.26%. Based on molecular analysis, all test lines already have the qTSN4 or qDTH8 gene locus, and all test lines also have the Xa7 gene locus.

TaAPO-A1, an ortholog of rice ABERRANT PANICLE ORGANIZATION 1, is associated with total spikelet number per spike in elite European hexaploid winter wheat (Triticum aestivum L.) varieties

We dissected the genetic basis of total spikelet number (TSN) along with other traits, viz. spike length (SL) and flowering time (FT) in a panel of 518 elite European winter wheat varieties. Genome-wide association studies (GWAS) based on 39,908 SNP markers revealed highly significant quantitative trait loci (QTL) for TSN on chromosomes 2D, 7A, and 7B, for SL on 5A, and FT on 2D, with 2D-QTL being the functional marker for the gene Ppd-D1. The physical region of the 7A-QTL for TSN revealed the presence of a wheat ortholog (TaAPO-A1) to APO1–a rice gene that positively controls the spikelet number on the panicles. Interspecific analyses of the TaAPO-A1 orthologs showed that it is a highly conserved gene important for floral development and present in a wide range of terrestrial plants. Intraspecific studies of the TaAPO-A1 across wheat genotypes revealed a polymorphism in the conserved F-box domain, defining two haplotypes. A KASP marker developed on the polymorphic site showed a highly significant association of TaAPO-A1 with TSN, explaining 23.2% of the total genotypic variance. Also, the TaAPO-A1 alleles showed weak but significant differences for SL and grain yield. Our results demonstrate the importance of wheat sequence resources to identify candidate genes for important traits based on genetic analyses.

Genetic bases of source-, sink-, and yield-related traits revealed by genome-wide association study in Xian rice

The source-sink relationship determines the ultimate grain yield. We investigated the genetic basis of the relationship between source and sink and yield potential in rice. In two environments, we identified quantitative trait loci (QTL) associated with sink capacity (total spikelet number per panicle and thousand-grain weight), source leaf (flag leaf length, flag leaf width and flag leaf area), source-sink relationship (total spikelet number to flag leaf area ratio) and yield-related traits (filled grain number per panicle, panicle number per plant, grain yield per plant, biomass per plant, and harvest index) by genome-wide association analysis using 272 Xian (indica) accessions. The panel showed substantial variation for all traits in the two environments and revealed complex phenotypic correlations. A total of 70 QTL influencing the 11 traits were identified using 469,377 high-quality SNP markers. Five QTL were detected consistently in four chromosomal regions in both environments. Five QTL clusters simultaneously affected source, sink, source–sink relationship, and grain yield traits, probably explaining the genetic basis of significant correlations of grain yield with source and sink traits. We selected 24 candidate genes in the four consistent QTL regions by identifying linkage disequilibrium (LD) blocks associated with significant SNPs and performing haplotype analysis. The genes included one cloned gene (NOG1) and three newly identified QTL (qHI6, qTGW7, and qFLA8). These results provide a theoretical basis for high-yield rice breeding by increasing and balancing source–sink relationships using marker-assisted selection.

Agro-morphological Variation in 71 Traditional Rice Cultivars in Sri Lanka

Traditional rice cultivars in Sri Lanka have diverse characteristics that prove the excellent potential for utilizing them for varietal improvement. Seventy-one Sri Lankan traditional rice cultivars obtained from Plant Genetic Resources Center, Gannoruwa, Sri Lanka were used for diversity analysis. Data were collected in the middle-row-plants of each replicate and altogether 80 plants were evaluated in four replicates of each cultivar. Data were collected on 11 parameters in two consecutive Maha seasons in 2012-2014. According to the standard evaluation system of international rice research institute, 67% rice cultivars were tall, and 66% were low tillering. There was no any rice cultivar with high and good reproductive tillers/plant. Around 55% rice cultivars were partially sterile and 43% were fertile. The shortest days to maturity was recorded in Gonabaru (62 days) and the longest days to maturity was recorded in Vellainellu (105 days).&#x0D; The variation of agro-morphological characteristics was broad in studied rice cultivars: The recorded highest yield was 22.74 g/plant while the lowest was 1.55 g/plant. The hundred-grain-weight ranged from 3.49-1.27 g and the plant height ranged from 95-192 cm. The recorded highest number of total tillers per plant was 10 and the lowest was 3. Panicle length and panicle weight were ranged from 13-32 cm and 0.36-4.69 g consecutively. The smallest grains were in Herath and the largest grains were in Mudaliwi. The heaviest above ground biomass was achieved by Kallurundoivellai and its harvest index was the least (0.09). The highest filled grain percentage (91.48%) was recorded by Galpa Wee.&#x0D; The correlation analysis revealed that the yield per plant was significantly correlated with panicle weight, the total number of spikelets/panicle and number of fertile spikelets/panicle. There was no correlation between panicle length and the final yield of rice though panicle length was correlated with plant height and panicle weight. Total number of spikelets/panicle, the number of fertile spikelets/panicle, and plant height were significantly correlated with panicle weight. None of the parameters were correlated with hundred grain weight. Total biomass was correlated with plant height, the total number of spikelets, and fertile spikelets per panicle. There was no significant correlation between the biomass of rice with the final yield, however, a number of fertile tillers were correlated with a number of total tillers.&#x0D; Eleven parameters were sorted into four principal components that explained 87.44% of total variance and cluster analysis categorized the rice cultivars into six clusters at rescaled cluster distance 10 in Ward's linkage analysis.

Effect of Zinc Fertilizer Application on Growth Yield and Yield Contributing Characters in Rice

Field experiment was carried out at the field of Department of Agronomy, BSMRAU campus, Gazipur, of Bangladesh during aman season (July-October) of 2017 to study the effect of zinc fertilizer application on growth, yield and zinc partitioning in three rice varieties: (BRRI dhan 56, BRRI dhan 57 and BRRI dhan 62) at three levels of zinc fertilization, no application of zinc, 10and 20 kg Zn ha-1. The highest leaf area indices of 3.15 in BRRI dhan 56, and 3.27 in BRRI dhan 57 were recorded with the application of 10 kg Zn ha-1 at 75 DAT and 3.28 in BRRI dhan 62 with 20 kg Zn ha-1. Through the growth period the SPAD value was the maximum at 10 kg Zn ha-1 in BRRI dhan 56 and BRRI dhan 57 and in BRRI dhan 62 at 20 kg Zn ha-1. The highest CGR, RGR, NAR were recorded at 10 kg Zn ha-1 in BRRI dhan 56 and BRRI dhan 57, and at 20 kg ha-1 in BRRI dhan 62.Zinc fertilizer at 10 kg Zn ha-1significantly increased the number of effective tiller m-2, length of panicle, total number of spikelet’s panicle-1,1000-grain weight, number of filled spikelet’s panicle-1, grain yield and straw yield in BRRI dhan 56 and BRRI dhan 57, and at 20 kg Zn ha-1 in BRRI dhan 62. It was revealed that the rice varieties BRRI dhan 56 and BRRI dhan 57 responded to the application of 10 kg Zn ha-1, while BRRI dhan 62 to 20 kg Zn ha-1.Overall results indicates, application of zinc might be necessary to ensure satisfactory yield.

Effect of Moderate Drought-Stress on Flowering Time of Interspecific Hybrid Progenies (Oryza sativa L. × Oryza glaberrima Steud.)

We examined the effects of drought stress on flowering time, grain yield, and agronomic traits using 10 upland-adapted rice genotypes, i.e. eight interspecific Oryza sativa L. ~ Oryza glaberrima Steud. (NERICA) lines and two Oryza sativa varieties—WAB56-104, the O. sativa parent of eight interspecific lines and IRAT 109, a drought-resistant variety as a check—under wet control and moderate drought-stressed conditions. Analysis of variance results for the 10 rice genotypes indicated that the effects of genotype (G) and drought stress (environment, E) were highly significant for tiller number, spikelet fertility, grain yield, straw dry-matter weight, and harvest index. Flowering was delayed by 1.7.10.7 (4.5 on average) days under drought condition compared with that under the wet control condition. Genotype (P < 0.001), drought stress (P < 0.001), and G ~ E interaction (P < 0.001) were highly significant with respect to days from seeding to 50% flowering (DTF50). DTF50 was significantly and negatively correlated with grain yield, yield components, and harvest index under drought-stress conditions. Of these, panicle number, total spikelet number, spikelet fertility, grain yield, and harvest index in drought-stressed rice genotypes were significantly and negatively correlated with DTF50 compared with those under the wet control condition. In conclusion, drought during the early vegetative stage inhibits most of the major agronomic traits by delaying flowering in upland-adapted rice genotypes.

Diallel analysis of yield and its important components in aromatic rice (Oryza Sativa L.)

Eight parents of aromatic rice were crossed in half diallel mating design without reciprocal including parents. The parents were evaluated for eleven different characters. Genetic analysis was done through Griffing’s Method II Model I. Analysis of variance revealed highly significant differences among parents and their crosses for all the characters. Combining ability analysis revealed that gca and sca variance were highly significant for most of the characters studied in F1 generation. Amongst the parental lines, Basmati Kasturi was a good general combiner for plant height at maturity, total number of spikelets per panicle, total number of filled grains per panicle and grain yield per plant in F1 generation while the most promising specific combiners for grain yield per plant were Basmati x Chakhao Angangba and Basmati Kasturi x Basmati 370.