Unfilled Spikelets Research Articles

Evaluating Panicle Architecture and Yield Characteristics in Medium Duration Rice Genotypes through Correlation and Principal Component Analysis

Panicle architecture is a crucial factor that significantly improves economic grain yield. The panicle exhibits considerable variation in its structure, including the number of branches, the length and weight of the panicle, and arrangement of the grains. These traits are not only vital for the plants reproductive efficiency but also for optimizing yield potential. This study focuses on assessing variation in panicle architecture among 31 different medium duration rice genotypes by employing principal component analysis and correlation analysis. This study aimed to dissect the complex relationship between different panicle characteristics. The findings revealed that the first three principal components together explained 60.3% of the total variability. In the first principal component (PC1), the traits SF, PBL, YPH, and HI had the highest positive eigenvalues, indicating their significant impact on overall genotype variations. The second principal component (PC2) was mainly influenced by TSP and SBN, while the third principal component (PC3) was driven by PW and SBL. These results suggest that grain yield is significantly affected by the traits SF, PBL, YPH, HI, TSP, SBN, PW, and SBL. The correlation analysis revealed that the number of secondary branches showed a positive association with unfilled spikelet. Spikelet fertility exhibited a strong positive correlation with yield hectare-1 and harvest index, highlighting its significance in overall yield improvement. Therefore, these components are crucial for differentiating rice genotypes with higher grain yield potential. By evaluating correlation and principal component analysis, we aimed to identify traits that can be targeted for crop improvement initiatives. The findings will contribute to the development of rice varieties that are better suited to specific growing conditions and have enhanced yield potential. This approach will enable the identification of key panicle architecture and yield and yield traits that optimize resource allocation and improve grain filling efficiency, ultimately leading to rice varieties with higher productivity and adaptability.

ESTIMATION OF COMBINING ABILITY AND HETEROSIS IN WHEAT

The study used a half-diallel mating fashion to identify combining ability (GCA and SCA) and heterosis of six wheat (Triticum aestivum L.) genotypes and their 15 F1 hybrids for morpho-physiological, yield, and yield-contributing traits. The present study was carried out in a randomized complete block design with three replications. The studied characters are heading days, maturity days, chlorophyll content, Plant height, Effective tillers plant-1, Total tillers plant-1, Spikes plant-1, Spike length, Filled spikelets spike-1, Unfilled spikelets spike-1, Grains spike-1, Thousand grain weight, Grain yield plant-1, Biological yield plant-1, and Harvest index Highly significant differences were observed among genotypes (parents and F1 hybrids) for all characters studied. The results also showed that the mean squares due to general (GCA) and specific (SCA) combining abilities were highly significant for all studied characters except harvest index, indicating the magnitude of both additive and non-additive gene effects in governing these traits. GCA/SCA ratios were greater than one for all characters except filled spikelets spike-1 and harvests index, indicating the dominance of additive gene effects, which play important roles in the inheritance of these characters. While the non-additive effect of the gene predominated in the inheritance of filled spikelets (spike-1) and harvests index, The parent BARI GOM-30 emerged as the best general combiner for total tillers plant-1, filled spikelets spike-1, grains spike-1, thousand-grain weight, grain yield plant-1, and harvest index. Bari Gom-28 was the best general combiner for heading days and maturity days, and Sourav was the best for effective tillers plant-1, spikes plant-1, and biological yield plant-1. The cross BARI GOM-30 SOURAV was the best specific combiner for effective tillers plant-1, total tillers plant-1, spikes plant-1, and PRODIP SOURAV for filled spikelets spike-1. Bari GOM-33 Sourav emerged as the best specific combiner for grain yield plant-1 and Prodip Ayt-5 for grain spike-1. Concerning heterotic effects in comparison to the midparent, the F1 hybrid BARI GOM-28 BARI GOM-33 showed maximum significant positive heterosis for chlorophyll content and biological yield plant-1 and BARI GOM-33 SOURAV for effective tillers plant-1, spikes plant-1, and grain yield plant-1. These parents and cross combinations could be used for the breeding program of wheat for potential yield.

Study of Black Rice Parents Performance and the Crossing Ability

Black rice generally has problems in cultivation such as relatively long plant life, high habitus and low productivity. Plant breeders use several methods in hybridization activities, such as backcross method that can lead to the development towards emphasizing the superiority of each parent. This research aimed to study and determined the success rate of the black rice lines F1 backcross and the parents’ performance. This research was conducted using F1 of promising lines, parental lines and the Jeliteng variety with 9 sets of crosses. Each line and variety were repeated 3 times, in total there were 57 experimental units. The observation parameters of this research were plant height, crossing success, weight of seeds, length and width of grain, flowering age, harvesting age also number of grains and unfilled spikelet. The results of this study showed that parents plant height was positively correlated with the number of productive tillers. The taller the plant, the more productive tillers and the more flowers can be crossed. The success of the cross can increase with the number of flowers crossed. The success of crosses between F1 black rice promising lines and their parents has a success rate range of 10.82% to 33.75%. The findings imply that F1 crossbreeding of black rice promising lines with their parents can be carried out to produce backcross offspring.

Growth and Yield Variability in Rice Owing to Root Knot Nematode (Meloidogyne Graminicola) At Different Plant Age

Meloidogyne graminicola (nematode) mostly attacks young roots of plants; hence, age of host becomes a predominant factor in infection and pathogenesis. A pot experiment was conducted in the net house condition during kharif, 2018 in complete randomized design to find out the changes in growth and yield parameters of rice cv. Naveen due to inoculation of M. graminicola at different plant age. The nematode infested rice plants showed chlorosis, stunting and characteristic terminal galls on the roots which ultimately resulted in severe reduction in growth, unfilled spikelets, reduction in tiller development and other growth attributes over control. Nematode inoculation at early crop stage retarded the plant growth and yield attributes by reducing the rice yield up to 57.4%. The maximum percentage of reduction in plant height (19.8%), tiller number (39.6%), dry weight of shoot (43.6%), dry weight of root (45.6%) and total biomass (49.6%) was observed in the plants inoculated at two weeks after sowing. Bangladesh J. Bot. 51(3): 411-416, 2022 (September)

Intercropping of upland rice with green manures in the Brazilian Cerrado

ABSTRACT Cereals and green manures intercropping contributes to sustainable agriculture as it combines food production with biomass for soil cover formation. This study aimed to evaluate the intercropping of rice and green manures effects on the agronomic and qualitative performance of rice, as well as dry mass yield for the no-tillage system. A two-year experiment with 8 treatments: rice as sole crop or intercropped with Arachis pintoi, Calopogonium mucunoides, Crotalaria breviflora, Crotalaria spectabilis, Stylosanthes capitata and macrocephala, Canavalia ensiformis, and Cajanus cajan was conducted in the Brazilian Cerrado region. The results showed that the shoot dry mass and height of plants was affected by the cultivated species. Rice intercropped with A. pintoi, C. mucunoides, C. breviflora, C. spectabilis and S. capitata and macrocephala promoted yield and grain quality similar to those found with rice as sole crop. Intercropping systems of rice with C. spectabilis, C. ensiformis and C. cajan increased the number of unfilled spikelets and reduced the number of filled spikelets and yield by 33, 24 and 58%, respectively. Intercropping systems with A. pintoi, C. mucunoides, C. breviflora, C. spectabilis, C. ensiformis and C. cajan produced adequate dry mass for the maintenance of soil cover in quality no-tillage system.

Genetic Divergence of Rice Genotypes Revealed by Bacterial Blight Disease and Morphological Traits

Bacterial blight is a perilous impediment for rice production. Resistant variety is a sustainable approach to fend off the loss of rice due to bacterial blight disease. In this study, 94 genotypes were screened against bacterial blight disease and its morphological diversity was assessed to find out the resistant donor with desirable morphological characters. Bacterial blight pathogen was inoculated following leaf clipping method for disease scoring. Out of 94 genotypes, 12 showed a resistant reaction, 13 showed moderately resistant reaction and 69 genotypes showed a susceptible reaction. Positive correlation was recorded between yield and most of the morphological characters. Yield hill─1 was significantly correlated with the number of tiller hill─1 (0.503**), number of effective tiller hill─1 (0.538**), total number of spikelets panicle─1 (0.595**), number of filled grain panicle─1 (0.595**), number of unfilled spikelet panicle─1 (0.239*) and 1000 grain weight hill─1 (0.843**). Eleven quantitative characters grouped 94 rice genotypes in 16 clusters at coefficient 3.38 and it indicated the presence of great amount diversity among the genotypes. Principal component analysis (PCA) supported the cluster analysis and the first four principal components explained around 70.99% of total divergence for all morphological characters. Principal coordinate analysis (PCoA) demonstrated that the genotypes BR8862-29-1-5-1-3, SVIN301, SVIN321, BR9207-45-2-2, SVIN018, lRBB5, SVIN038, BRRI dhan28 and BRRI dhan29 were placed in distant position from the centroid and it indicated that they were more diverse than the genotypes near the centroid. However, based on disease reaction and genetic diversity analysis crossing could be made between, resistant genotypes such as SVIN317, SVIN017, SVIN316, SVIN313, SVIN315, SVIN314, SVIN038, SVIN307, SVIN302, SVIN304 with the susceptible variety more specifically with BRRI dhan28, BRRI dhan29, BRRI dhan50, BRRI dhan58, BRRI dhan63, BRRI dhan74, BRRI dhan81 and BRRI dhan84 to develop bacterial blight resistant variety.
 Bangladesh Rice J. 24 (1): 73-84, 2020

Genetic Variation, Heritability and Genetic Advance in Some Promising Rice Hybrids

Eleven rice hybrids including two check varieties were evaluated to approximate their genetic variability, heritability and genetic advance for ten quantitative traits. The analysis of variance illustrated that all the quantitative traits differed significantly indicating that enough variation is presenting the studied materials. Among the desirable quantitative traits number of filled spikelet’s per panicle was found to have highest both phenotypic and genotypic variance followed by total number of spikelet’s per panicle. Almost all the characters showed a little variation between PCV and GCV revealing little influence of the environment on the expression of traits. High phenotypic and genotypic variance coupled with high heritability and high genetic advance was observed for number of filled spikelet’s per panicle, total number of spikelet’s per panicle, plant height and number of unfilled spikelet’s per panicle. Such findings stipulated that these traits were governed by additive gene actions which are fixable and these traits may be accounted for reliable index of selection. The genotypes G3 (IR79156A × EL108R) and G6 (IR79156A × EL253R) were selected as high response superior promising rice hybrids for achievable yield advantage 49% and 23%, respectively over best check varieties. Therefore, the G3 and G6 are proposed to be extensively evaluated for further trial of variety release.
 SAARC J. Agri., 18(2): 39-49 (2020)

Correlation studies in seedling and reproductive stage salinity tolerance in rice (Oryza sativa L.) under salinity

Salinity is a major abiotic stress limiting rice productivity worldwide. The present study had 234 F2:3 population of a salt-tolerant donor Indra (MTU 1061) in the genetic background of Sri Druthi (MTU 1121) to elucidate the genetic basis of seedling and reproductive stage salinity tolerance. The F2:3 population were evaluated under salt stress at seedling stage (EC 6 &12 dSm-1) and reproductive stage (EC 6 & 12 dSm-1). At seedling stage, salt injury score had positive significant correlation with shoot Na+ concentration and Na/K ratio while it was negative & significant with K+ concentration, shoot length, root length and shoot dry weight. This indicated that homeostasis between Na+ and K+, plays a key role in the seedling stage tolerance to salt stress. In reproductive stage grain yield per plant play pivotal role for salinity tolerance comparative to remaining parameters such as number of spikelets, filled spikelets and unfilled spikelets. Results showed positive significant correlation of grain yield with days to flowering, number of total grains and productive tillers while it was negative significant with panicle length. The results of this study confirmed that salinity tolerance at the seedling and reproductive stages are independent to each other.

Response of Black, Red, and White Rice (Oryza sativa L.) Cultivars to Nutrient Management Under Highly Alkaline Soil

Increasing rice productivity under highly alkaline soil is possible by using appropriate cultivars and efficient nutrient management. This study determined the agronomic and yield response of three rice cultivars to nutrient management under highly alkaline soil. It evaluated rice production's profitability using three rice cultivars influenced by nutrient management under highly alkaline soil. The experiment was laid out in a split-plot arranged in an RCBD with rice cultivars as the main plot and nutrient management as the subplot. Statistical analysis revealed that fertilized plants headed and matured earlier than unfertilized plants. A significant interaction effect was noted among rice cultivars under different nutrient management. The combination of organic and inorganic fertilizers increased the percentage of filled spikelets while reducing unfilled spikelets. Application of 2.5 t/ha-1 poultry litter + 60-30-30 kg ha-1 N, P O , and K O (T ), significantly increased the 2 5 2 4 number of productive tillers, the weight of grains hill-1, and grain yield (t/ha-1) compared to plants applied with pure inorganic fertilizer. For cost and return analysis, black rice and T achieved the highest gross margins of PHP 297,708.28 4 and PHP 269,845.68 respectively. The results indicated that using black rice applied with 2.5 t/ha-1 poultry litter + 60-30-30 kg ha-1 N, P O , and K O (T ) is a highly effective 2 5 2 4 and profitable option for lowland rice production under highly alkaline soil.

Dissecting the Genetic Basis of Lateral and Central Spikelet Development and Grain Traits in Intermedium-Spike Barley (Hordeum vulgare Convar. Intermedium).

Barley (Hordeum vulgare L.) is one of the major grain crops worldwide and considered as a model plant for temperate cereals. One of the barley row-type groups, named intermedium-barley, was used in our previous study where we reported that other genetic loci rather than vrs1 and Int-c could play a role in lateral spikelet development and even in setting grains. To continue this work, we used phenotypic and genotypic data of 254 intermedium-spike barley accessions aimed at dissecting the genetic basis of development and grain traits of lateral and central spikelet using genome wide association (GWAS) analysis. After genotypic data filtering, 8,653 single-nucleotide polymorphism (SNPs) were used for GWAS analysis. A total of 169 significant associations were identified and we focused only on the subset of associations that exceeded the p < 10−4 threshold. Thirty-three highly significant marker-trait-associations (MTAs), represented in 28 different SNPs on all seven chromosomes for the central and/or lateral spikelet traits; such as kernel length, width, area, weight, unfilled spikelet and 1000-kernel weight, were detected. Highly significant associated markers were anchored physically using barley genome sequencing to identify candidate genes to either contain the SNPs or the closest gene to the SNP position. The results showed that 12 MTAs were specific for lateral spikelet traits, nine MTAs were specific for central spikelet traits and seven MTAs for both central and lateral traits. All together, the GWAS and candidate gene results support our hypothesis that lateral spikelet development could be regulated by loci different from those regulating central spikelet development.

Cd accumulation, biomass and yield of rice are varied with silicon application at different growth phases under high concentration cadmium-contaminated soil.

Many reports suggest that exogenous Si addition could reduce Cd translocation to aerial part and make grain safe for rice production. But it remains unclear whether its supplementation during different growth phases can differentially impact Cd uptake in rice. Here, Positive effects of Si applied at different growth phases on biomass and yield of rice were observed. Dry weight of shoot including stem, leaf and grain was enhanced significantly by 15% when Si added at transplanting stage. Grain-yields supplied with Si at transplanting, jointing and heading stages were increased obviously by 14%, 11% and 12%, respectively. Higher percentage of filled spikelet and lower unfilled spikelet number per panicle were found when Si supplied at jointing stage. The increases of Cd accumulation in rice plants by Si application were mainly manifested in roots. Compared to CK, Cd accumulation in root when Si applied at transplanting and tillering stages were elevated by 75% and 64%, respectively. While Cd accumulation in aboveground tissues were all declined by Si addition. Bioconcentration and translocation factors were decreased significantly when Si added at jointing stage. In addition, higher soil pH, lowest available Cd-concentration in soil and Cd2+ concentration in xylem sap at 15d after flowering were found when the Si was applied at jointing stage. Overall, Si application at transplanting would be more beneficial to the growth of rice and increased Cd content in root, while Si supplied at jointing would be more favorable for grain filling and reducing Cd accumulation in shoot.

Yield Response of African Rice Genotypes to Mycorrhizal Fungi and Rhizobium Inoculation

Aims: A short term field study was conducted to investigate the yield performance of selected African rice genotypes inoculated with biofertilizers. &#x0D; Study Design: A randomized complete block design laid out in a split-plot arrangement was used to evaluate response of yield components and grain yield of some selected African rice genotypes will be to mycorrhizal fungi and rhizobium inoculation.&#x0D; Place and Duration of Study: The study was conducted at the Teaching and Research farm of the Federal university of technology, Akure Ondo state, Nigeria during the 2013 planting season.&#x0D; Methodology: The study was laid out in a split plot arrangement in Randomized Complete Block Design (RCBD), with mycorrhizal fungi, rhizobium inoculation and control in the main plot, while genotypes (N-U-1, N-U-8, WAB 56-104, OFADA GR and MOROBEREKAN) were in the sub-plot and treatments were replicated thrice. There were three main blocks, each block consist of 15 sub-plots with a size measurement of 2m x 1m and inter sub-plot spacing of 0.5m in between plots. A total of 50 plants were raised per sub plot. Transplanted seedlings were planted with the soil slurry containing rhizobium and mycorrhizal fungi inoculum into planting holes in the field at two seedlings per stand, according to their respective plot at a spacing of 25cm x 25cm. Yield component data collected include; number of days to 90% maturity, number of days to 50% flowering; plant height at maturity, number of primary tillers per plot, number of grains per panicle, number of panicles, number of filled and unfilled spikelet, weight of 1000 filled grains and grain yield per plot. &#x0D; Results: Result showed significant (P&lt;0.05) single and interactive effect of rhizobium and mycorrhizal fungi inoculation on rice yield and yield components. 61.4% increase in grain yield was observed in rhizobium inoculated genotypes when compared to 37.4% increase in mycorrhized genotypes and the un-inoculated control. WAB56–104 and N-U-8 had the best interactive response amongst genotypes inoculated with rhizobium while genotypes WAB56-104 and MOROBEREKAN responded better amongst mycorrhized genotypes in relation to yield components.&#x0D; Conclusion: The results from this study indicate that African rice genotypes differ in grain yield response and host specifity when inoculated with mycorrhizal fungi and rhizobium inoculums. However, inoculating specific African rice genotypes with mycorrhizal fungi and rhizobium can positively influence their grain yield and yield component development and this could play an important role in improving African rice productivity.

Effect of Sowing Dates on Yield and Yield Attributes of Rice Genotpes

In order to investigate the effect of sowing dates on rice yield and its components a field experiment was carried out in Randomized Complete Block Design (RCBD) with three replications at the Experimental Farm of Sakha Agricultural Research Station, Sakha, Kafr EL-Sheikh Egypt. 14 rice genotypes were tested at different sowing dates, April 1st, April 15th, May 1st and May 15th during the two successive rice seasons 2017 and 2018. The studied characters were i.e., flag leaf area, chlorophyll content, plant height, number of panicles per hill, number of filled grains per panicle, number of unfilled spikelets per panicle, 1000-grain weight (g), grain yield (t/ha), number of days from sowing to heading and growth degree days. Analysis of variance indicated that rice genotypes were significantly different for all the studied traits. The highest values of grain yield and most of the studied characters were observed under April 15th followed by May 1st sowing dates. Sakha108 and GZ6903-1-2-2-1 produced the highest grain yield followed by IR77510-68-1-3-3.

Effect of submergence durations on yield and yield contributing characters of hybrid and inbred aman rice

The trend of increasing submergence has a negative effect on the rice yield but among them, some of the genotypes show the excellent performance to give a satisfactory yield. The experiment comprised of two factors-factor a: submergence duration (4): control, 6 days, 10 days and 14 days and factor b: rice variety (6): hybrid (BRRI Hybrid dhan3, ACI Shankar and Heera-2) and inbred (BRRI dhan34, BRRI dhan46 and BRRI dhan51). The experiment was laid out in a randomized complete block design (RCBD) with three replications. Significant variation was found on different yield contributing characters and yield with submergence durations. In all the varieties, the control treatment (0 days submergence) showed the highest values (except the number of unfilled spikelets panicle-1) and was gradually decreased with increasing submergence duration from 6 days to 14 days. The lowest reduction due to submergence was recorded in BRRI dhan51, which was followed by BRRI dhan46. Attaining better yield, which was near about control, the varieties BRRI dhan51 and BRRI dhan46 proved them as relatively submergence tolerant compared to other varieties.&#x0D; Asian Australas. J. Biosci. Biotechnol. 2018, 3 (3), 225-230

Pengaruh Periode Kekeringan Terhadap Pertumbuhan dan Hasil Beberapa Genotipe Padi

&lt;em&gt;The objective of this experiment was to identify the growth and production responses of rice genotypes to drought period. Rice plants were grown under plastic house in plots separated by a massive walls and water was suplied by inlet pipe line. Drought treatments were placed as main-plot, consisted of K3, K6, K9 (water was supplied till 3, 6, and 9 weeks after rice transplanting (WAT), respectively) and control (standard rice growing without drought treatment).� Rice genotypes were placed as sub-plot, consisted of IR-64 and Ciherang (low land type improved varieties), IPB-97 (new plant type), Menthik Wangi (an aromatic local low land rice), Rokan (a hybryd rice), Way Apo Buru (amphibian type), Jatiluhur and Silugonggo (up land type). The results showed that rice growth and yield were significantly affected by drought treatment, especially in K3 and K6. Low yield in K3 and K6 were mostly caused by increased of unfilled spikelet. Jatiluhur, Ciherang and Way Apo Buru still showed relatively high yield under drought stress indicated that those genotypes were relatively tolerant to drought stress; Silugonggo and IPB-97 showed relatively medium tolerant to drought stress; IR-64, Menthik wangi and Rokan showed the most sensitive one.&lt;/em&gt;

Effect of Biogenic Silica Nanoparticles on Blast and Brown Spot Diseases of Rice and Yield Component

Rice is considered as one of the most important food crops in the world. Rice plants infected by several plant pathogens. In Egypt, however important diseases of rice namely blast and brown spot are major limitation on rice production and becoming more sever on rice grown in silicon depleted soil. Disease that occurs to plant may reduce the ability of the plant to survive and in more severe cases could eventually lead to plant death. Two field experiments were carried out to study the effect of different sources of biogenic silica nanoparticles on blast, brown spot diseases and yield component in rice at Rice Research and Training Center Experimental Farm, Sakha, Kafr El-Sheikh, Egypt. Theeffect of different sources of silica on the behavior and infection by rice blast on Sakha 101 rice variety had been studied in thefirst experiment. While the second experiment included the behaviorand infection bybrown spot of Egyptian Hybrid Rice One under silica nanoparticles biogenic treatments. The silica treatments were white rice husk, rice husk nanoparticles, white rice straw, rice straw nanoparticles, Mg2O8 Si3, and K2 SiO2. Chemicalfungicides (Beam and Del-Cup) and tap water were used as control. Different biogenic and chemical silica led to decreasing blast disease infection in Sakha 101 compared with control (tap water). Most of the agronomic characters of Sakha 101 were affected significantly by different treatments. All treatment of different biogenic and chemical silica sources decreased the leaf infection percent and severity for brown spot disease on Egyptian Hybrid Rice One. Different treatments significantly affected panicle length, number of filled grains per panicle, number of unfilled spikelets per panicle, 1000-grain weight, and grain yield and harvest index of Egyptian Hybrid Rice One. The result of this study suggests that silica caused decrease the intensity of blast and brown spot diseases.

Stalk rot fungi affect grain sorghum yield components in an inoculation stage-specific manner

Although stalk rots are among the most prevalent and destructive diseases of sorghum, no systematic crop loss assessment has been reported for these diseases under controlled-inoculations. The objective of this study was to assess the impacts of Fusarium stalk rot and charcoal rot on grain sorghum yield components when plants were inoculated at two growth stages (GS). Four genotypes were field evaluated against three Fusarium spp. (F. thapsinum, F. proliferatum, F. andiyazi) and Macrophomina phaseolina. Inoculations were performed at GS1 (30 d after emergence) and GS3 (14 d after flowering). Panicles were harvested at physiological maturity and assessed for total seed weight (TSW), 100-seed weight (100-SW), and total seeds per panicle (TSP). The total number of reproductive sites and unfilled spikelets were counted per rachis (TRSR and NUSR, respectively) and panicle (TRSP, NUSP) bases. Length and nodes crossed by the lesion in split stems were measured to evaluate disease severity. Pathogens significantly reduced TSW in comparison to the control at both GS1 and GS3. The four pathogens, on average, caused greater TSW reductions when inoculated at GS1 (52%) than at GS3 (37%). All pathogens reduced TSP upon GS1 inoculation and 100-SW upon GS3 inoculations. All pathogens significantly reduced seed set percentage when plants were inoculated at GS1 while inoculations at GS3 did not have a significant impact. GS1 inoculations significantly decreased TRSP, demonstrating pathogen interference with head formation resulting in smaller heads than control. Although inoculations at GS1 had a greater impact on yield, inoculations at GS1 and GS3 did not significantly differ in disease severity. This study revealed inoculation stage-specific effects of stalk rot pathogens on yield parameters and provided insights into key yield traits to be emphasized in sorghum breeding programs to produce stalk rot tolerant sorghum genotypes.

Performance of Rice Tungro Resistant Promising Line in Endemic Area

Tungro disease is one of the important diseases of rice because it has a high potential for causing damage. The use of varieties resistant to the tungro disease effectively prevent an explosion tungro disease. Testing of promising lines resistant to the tungro at several locations is a stage in the breeding program before a line is released as a new variety that has resistance to tungro disease, as well as having the potential for high yields and good adaptation at several locations. Six of tungro resistant promising line (OBSTG02-137, OBSTG02-124, OBSTG02154, OBSTG02-130, OBSTG02-56, dan OBSTG02-37) and four check varieties (Inpari 9 Elo, Tukad Unda, Ciherang, and IR64) were evaluated for their yield potential and adaptability at 16 locations in tungro endemic area during the dry season of 2011-2013. The experiment was arranged in a randomized block design with 3 replications. Each line were transplanted in 4 m x 5 m plot size with plant spacing 25 cm x 25 cm. Observation were made on yield, 50% flowering date, plant heights, panicle number per hill, number filled and unfilled spikelets per panicle, and weigh of 1000 grains in gram. The results showed that effect of genotype x location interaction was significantly different for all component observed. Based on the performance of grain yield and yield components obtained, four lines i.e. OBSTG02-137 (6.74 t/ha), OBSTG02-124 (6.20 t/ha), OBSTG02-154 (6.37 t/ha ), and OBSTG02-130 (5,92 t/ha) has a high yield with the support of filled grain number and weight of 1000 seeds is high. Based on the combined value of bi and the general average of yield, then line OBSTG02-137, OBSTG02-154, and OBSTG02-130 were suitable to adapt to all environments, OBSTG02-124 is adapted in an optimal environment, OBSTG02-56 and OBSTG02-37 were adapted to the less productive environment.

Lodging Resistance and Yield Performance of Two Traditional Rice Varieties Applied with Nitrogen and Paclobutrazol

Vulnerability of rice growing areas to strong typhoons coupled by the susceptibility of traditional rice varieties to lodging lead to low yield and poor quality of harvested rice. To address these problems, two experiments using factorial in Randomized Complete Block Design were conducted during the wet season to determine the effects of paclobutrazol and nitrogen on the lodging resistance, agro-morphological characteristics and yield performance of two traditional rice varieties Elon-elon and Palawan Red. Application of increasing concentration of paclobutrazol did not significantly affect the percentage filled spikelets per panicle, number of spikelets per panicle, weight of 1000 grains, dry matter yield, harvest index and grain yield. At all concentrations of paclobutrazol, Palawan red had the longest first and fourth internodes, more unfilled spikelets per panicle, heavier 1000 grains weight and higher leaf area index than Elonelon. On the other hand, smaller stem diameter, more productive tillers per hill and longer panicles were obtained from Elon-elon than Palawan red. Elon-elon applied with increasing rates of nitrogen in combination with 500 ppm paclobutrazol had bigger stem diameter, higher productive tillers per hill, higher number of filled spikelets per panicle, higher percentage filled spikelets per panicle, longer panicles, higher harvest index and higher grain yield than Palawan red. Apparently, Palawan red had longer first, second and third internodes, more unfilled spikelets per panicle, heavier 1000 grain weight and higher leaf area index than Elon-elon. Applications of 30 and 60 kg N per ha had significantly higher lodging index than the untreated plants. Harvest index and grain yield were lowest in plants applied with 30 and 60 kg N per ha, attributable to high lodging index. Paclobutrazol is effective in shortening the length of the lower internodes and inhibits stem elongation resulting to shorter plants with increased lodging resistance. This ultimately produced higher yield than those plants that lodged. Culm strength was reduced by high rates of nitrogen causing significant increase in lodging index. The time of lodging is crucial in predicting the yield performance of the plants. Early lodging resulted to huge reduction in yield while it has little or no effect on yield when it occurs at later stages of the rice crop.

A quantitative measure for assimilate partitioning efficiency in rice (Oryza sativa L.)

Grain filling in rice is determined by the balance between sink size and source supply. Partially filled or unfilled spikelets is produced when source supply per spikelet is insufficient. Cultivars with high assimilate partitioning efficiency, which produce fewer partially filled spikelets, would be preferable because the grains of partially filled spikelets have low market value. However, it is unclear whether there is a genotypic difference in assimilate partitioning efficiency, and there is no quantitative measure for this parameter. The objective of this study was to develop such a measure from the relation between grain-filling percentage (GFP) and percentage of filled spikelets (PFS) of cultivars with various grain-filling abilities. GFP is a dry-weight-based grain filling degree, i.e. the ratio of total hulled grain yield to the sink capacity. PFS is a spikelet-number-based grain filling degree, i.e. the proportion of the number of filled spikelets to the total number of spikelets per area. We investigated the factors associated with partitioning efficiency based on grain weight distribution during grain filling. We also determined the filling potential of empty spikelets, which are indistinguishable from unfertilized ones, under limited assimilate supply. Cultivars with a large (indica-dominant Takanari, japonica-dominant Momiroman) or moderate sink size (indica Kasalath, japonica Koshihikari) were grown in a paddy field and defoliated at full heading to limit assimilate supply. Grain weight distribution was investigated at 10, 20, and 30days after anthesis. Yield, yield components, and shoot dry matter were measured at maturity. We found an exponential relation between GFP and PFS, which can be transformed to Ln(PFS)=B +A×GFP, with regression coefficients A varying among cultivars. A lower regression coefficient shows a higher assimilate partitioning efficiency and production of fewer partially filled spikelets. In indica and indica-dominant cultivars, which have lower regression coefficients, the difference in the weight of fast- and slowly-growing grains was larger than in japonica and japonica-dominant cultivars, suggesting an association between assimilate partitioning efficiency and the initial grain growth rate of fast-growing superior spikelets. We found that empty spikelets caused by low assimilate supply were fertilized and had a filling potential. In conclusion, the results suggest the regression coefficient between GFP and Ln(PFS) differs among cultivars with different grain filling abilities, and could be used as a quantitative measure of assimilate partitioning efficiency in rice breeding.