Percentage Of Sterility Research Articles

Male meiosis, morphometric analysis and distribution pattern of 2× and 4× cytotypes of Ranunculus hirtellus Royle, 1834 (Ranunculaceae) from the cold regions of northwest Himalayas (India).

In this study, we examined the chromosome number, detailed male meiosis, microsporogenesis, pollen fertility and morphological features and distribution of 2× and 4× cytotypes of Ranunculus hirtellus Royle, 1834. The majority of the populations scored now from cold regions of the northwest Himalayas showed tetraploid (n=16) meiotic chromosome count and one of the populations studied from the Manimahesh hills existed at diploid level (n=8). The individuals of diploid cytotype exhibited perfectly normal meiotic course resulting in 100% pollen fertility and pollen grains of uniform sizes. On the other hand, the plants of the tetraploid cytotype from all the populations in spite of showing normal bivalent formation and equal distribution to the opposite poles at anaphases showed various meiotic abnormalities. The most prominent among these meiotic abnormalities was the cytomixis which involved inter PMC (pollen mother cell) chromatin material transfer at different stages of meiosis-I. The phenomenon of cytomixis induced various meiotic abnormalities which include chromatin stickiness, pycnotic chromatin, laggards and chromatin bridges, out of plate bivalents at metaphase-I, disoriented chromatin material at anaphase/telophase and micronuclei. Consequently, these populations exhibited varying percentages of pollen sterility (24 - 77 %) and pollen grains of heterogeneous sizes. Analysis of various morphometric features including the stomata in 2× and 4× cytotypes showed that increase in ploidy level in the species is correlated with gigantism of vegetative and floral characters and the two cytotypes can be distinguished from each other on the basis of morphological characters. The distribution patterns of the 2× and 4× cytotypes now detected and 2×, 3×, 4× cytotypes detected earlier by workers from other regions of the Indian Himalayas have also been discussed.

Comportamento de genótipos de arroz de terras altas na Zona da Mata de Pernambuco

Avaliou-se, neste estudo, o comportamento de 12 genótipos de arroz de terras altas na Zona da Mata de Pernambuco quanto a caracteres de importância agronômica. Utilizou-se o delineamento de blocos ao acaso, com 4 repetições, parcelas constituídas de 5 linhas de 4 m e espaçamento de 0,50 m. Os experimentos foram conduzidos no ano agrícola de 2006, entre os meses de abril e agosto, nos municípios de Palmares e Vitória de Santo Antão. Dentre os caracteres avaliados verificaram-se diferenças significativas entre os genótipos para os caracteres: altura de planta, acamamento, ciclo de florescimento e de maturação, perfilhamento médio, comprimento de panículas, peso de mil grãos e rendimento de grãos inteiros. A interação genótipo x ambiente foi significativa para os caracteres altura de planta, ciclo de florescimento e percentual de espiguetas estéreis. Os genótipos Bonança, BRA 1506, CNAs 9045 e BRSMG curinga, apresentaram os melhores comportamentos para os caracteres: altura da planta, acamamento, ciclo de florescimento e de maturação, além de bom perfilhamento e médio rendimento e, portanto, são os mais promissores a serem recomendados para o plantio na referida região, especificamente no período entre os meses de abril a julho.

Mutagenic effectiveness and efficiency in varieties of sunflower (Helianthus annuus L.) by separate and combined treatment with gamma-rays and sodium azide

The effect of single treatment with gamma-rays, sodium azide and combination treatments of gammarays and sodium azide on seed germination, seedling survival, pollen fertility and seed set in sunflower (Helianthus annuus L.) M2 generation was studied in the varieties of USH-430 and SHSF-333. There was gradual decrease of seedling survival and pollen fertility with an increase in the dose of mutagen in both varieties. The percentage of lethality and achene sterility gradually increased with an increased dose. In USH-430 variety, the seed set percentage was significantly increased at 6kR, 4 mM and 6 kR + 6 mM, respectively. Mutagenic effectiveness decreased with an increased dose or concentration of gamma-rays and sodium azide in both varieties. In combined treatments, mutagenic effectiveness gradually increased with an increased dose. Mutagenic efficiency increased with an increased dose in case of gamma-irradiated seeds in both varieties. Mutagenic efficiency decreased gradually with an increased dose in both varieties. The linear correlation co-efficient was positive in case of gamma-rays and sodium azide separated, whereas in combined treatment, negative correlation was observed.

Radio sensitivity studies of morpho-physiological characteristics in some Iranian rice varieties (Oryza sativa L.) in M1 generation.

Gamma (γ) ionizing ray is a physical mutagen, producing variation in crop improvement and employing such as a complementary tool in breeding process. The γ-ray dosages are a critical issue, so it should be optimized. In this research, various doses of gamma radiation including 150, 250, 350 and 450 Gy applied on three rice varieties (Tarom-hashemi, Sange-tarom and Nemat), and their effects were evaluated on 50% lethal dose (LD50), rate and percent of germination, radicle and plumule length at in vitro, including cluster analysis of dosage quantities at genotypes, range of variation (R), variation coefficient of treatment regarding to control dosage (CVt/CVnt). Euclidean similarity coefficient including UPGMA (Unweighted Pair Group Method with Arithmetic Mean) algorithm was used for cluster analysis. The results indicated that 250 and 350 Gy γ-rays have much more better effects to create variation rather than other doses and also clearly showed that γ-ray made novel variation in panicle sterility percentage, plant height, 1000 grain weight and fertile tillers on the studied varieties. Meanwhile the dendrogram of clustering classified into 3 groups on the base of gamma effects and control doses were placed in different groups. The LD50 values related to seed germination computed 350, 310 and 170 at Sange-tarom, Tarom-hashemi and Nemat respectively. Key words: Gamma ray, rice, mutation, morpho-physiological characteristics.

Appraisal of a Chemical-Hybridizing Agent for Emasculation in Rice

Rice productivity can be enhanced through exploitation of heterosis in hybrids with a possible positive impact on food security. Making planned crosses is difficult in rice because of the morphology and size of the inflorescence. This study was undertaken to investigate the efficacy of a gametocide (ethrel) as an emasculating agent. Experiments were conducted at ICRISAT Research Station at Samanko in Mali during 2004–2005. A factorial arrangement in a randomized complete-block design involving three levels of concentrations of the gametocide and five application stages was undertaken for two seasons. Morpho-physiological trait responses and spikelet sterility data were recorded on the female treated plants. Ethrel could induce 40 to 49% male sterility in rice. Percentage of empty spikelets and male sterility increased with increasing concentration of ethrel, reaching a peak between 2,000 ppm (2.0 g L−1) and 4,000 ppm (4.0 g L−1). Male sterility induction of 41.5% and 42.8% at 2000 ppm was achieved in 2004...

Identification of a Rice stripe necrosis virus resistance locus and yield component QTLs using Oryza sativa × O. glaberrima introgression lines

BackgroundDeveloping new population types based on interspecific introgressions has been suggested by several authors to facilitate the discovery of novel allelic sources for traits of agronomic importance. Chromosome segment substitution lines from interspecific crosses represent a powerful and useful genetic resource for QTL detection and breeding programs.ResultsWe built a set of 64 chromosome segment substitution lines carrying contiguous chromosomal segments of African rice Oryza glaberrima MG12 (acc. IRGC103544) in the genetic background of Oryza sativa ssp. tropical japonica (cv. Caiapó). Well-distributed simple-sequence repeats markers were used to characterize the introgression events. Average size of the substituted chromosomal segments in the substitution lines was about 10 cM and covered the whole donor genome, except for small regions on chromosome 2 and 4. Proportions of recurrent and donor genome in the substitution lines were 87.59% and 7.64%, respectively. The remaining 4.78% corresponded to heterozygotes and missing data. Strong segregation distortion was found on chromosomes 3 and 6, indicating the presence of interspecific sterility genes. To illustrate the advantages and the power of quantitative trait loci (QTL) detection using substitution lines, a QTL detection was performed for scored traits. Transgressive segregation was observed for several traits measured in the population. Fourteen QTLs for plant height, tiller number per plant, panicle length, sterility percentage, 1000-grain weight and grain yield were located on chromosomes 1, 3, 4, 6 and 9. Furthermore, a highly significant QTL controlling resistance to the Rice stripe necrosis virus was located between SSR markers RM202-RM26406 (44.5-44.8 cM) on chromosome 11.ConclusionsDevelopment and phenotyping of CSSL libraries with entire genome coverage represents a useful strategy for QTL discovery. Mapping of the RSNV locus represents the first identification of a genetic factor underlying resistance to this virus. This population is a powerful breeding tool. It also helps in overcoming hybrid sterility barriers between species of rice.

Cytological effects of different mutagens in soybean [Glycine max (L.) Merrill

The effect of gamma rays, ethyl methane sulphonate, and their three combinations on various cytological parameters in M1 generation was studied in two soybean cultivars, Pusa-16 and PK-1042. Combined treatments exhibited high meiotic abnormalities in Pusa-16 as compared with the individual treatments of ethyl methane sulphonate and gamma rays. In PK-1042 the highest frequency of meiotic abnormalities was exhibited by gamma rays, while in Pusa-16 the frequencies of univalents were high as compared with other meiotic abnormalities. Fragments/bridges, laggards, ring and rod bivalents were other types of meiotic abnormalities that were noticed in both the cultivars. The frequencies of irregular cells in the two cultivars were high in combined treatments followed by ethyl methane sulphonate and gamma rays. The highest percentage of pollen sterility was exhibited by the combined treatments and the lowest was exhibited by gamma rays. In Pusa-16, the increase in doses of gamma rays and ethyl methane sulphonate increased the pollen sterility percentage, while in the combined treatments, the increase was noticed up to the intermediate dose and then gradually decreased at higher doses. On the other hand, in PK-1042 the increase in ethyl methane sulphonate dose increased sterility percentage, while no definite trend was noticed in gamma rays and combined treatments.

Evaluation of some hybrid rice varieties in under different sowing times

A field experiment was conducted in the experimental farm of Rice Research and Training Center (RRTC) – Sakha, Kafr- El Sheikh Governorate, and Egypt during rice season in 2008 for physiological evaluation of some hybrid rice varieties in different sowing dates. Four hybrid rice H1, H2, GZ 6522 and GZ 6903 were used. Seeds were sown on six different sowing dates April 10th, April 20th, May 1st, May 10th, May 20th and June 1st; and seedlings of 26 days old were transplanted at 20 ´20 cm spacing. All agricultural practices recommended for each cultivar were applied. Nitrogen fertilizer was used as urea (46.5% N) in two splits; that is, 2/3 were added and mixed in dry soil before flooding of irrigation water and the other 1/3 was added at panicle initiation stage. Experimental design was spilt plot design, with sowing dates as main and varieties as sub plot treatments. Results indicated that early date of sowing (April 20th) was superior to other dates of sowing for MT, PI, HD, number of tillers /M2, (plant height and root length) at PI and HD stage, chlorophyll content, number of days up to PI and HD, leaf area index, sink capacity , spikelets-leaf area ratio, number of grains / panicle, panicle length(cm), 1000-grain weight (g), number of panicles/ M2, panicle weight (g) and grain yield (ton/ha). Sterility percentage was the lowest in sowing 20th April. 1st of June, sowing gave the lowest with all traits under study. H1 hybrid rice variety surpassed other varieties for all characters studied except for number of days to PI and HD. Key words: Sowing dates, hybrid rice, physiological characters and yield.

Some inorganic salts for production of sterile adults of the red palm weevil Rhynchophorus ferruginous (Coleoptera:Curculionidae)

Fifteen inorganic salts were evaluated as possible sterilants against the Red Palm Weevil (RPW) Rhynchophprus ferrugineus , by applying the pupal dipping method in a screening program. Results showed that all tested salts adversely affected the adult emergence and reduced the egg laying capacity and egg hatchability. Among the tested salts a (oH)2, kOH, Licl2,cucl2 ZnO4, kBr and KI various gave 100% percent sterility at the tested non toxic concentration under different pupal dipping periods. Percentage of sterility increased with the increase of the concentration and the dipping period. All other salts induced degrees of sterility ranging from 10 to 78%.

Ethylene control of seed coat development in low and high sterile semidwarf indica rice cultivars

Although basally positioned inferior spikelets of rice panicles emerge late from the flag leaf enclosure (boot), they mature early which precludes adequate grain filling. It is assumed that extended exposure to ethylene inside the boot restricts assimilate partitioning to the endosperm in basal spikelets by affecting the functions of seed coat. In the present study, ethylene concentration inside the boot was measured in two high yielding rice cultivars differing in percentage of spikelet sterility. To manipulate the concentration/action of ethylene, silver nitrate, aminoethoxyvinyl glycine and 2-chloroethylphosphonic acid were injected into the boot. The effect of these chemicals on the concentration of photosynthetic pigments, lipid peroxidation and peroxidase activity of the seed coat and lemma and palea were measured to monitor development. Ethylene reduced development during the juvenile phase but accelerated degradation of the photosynthetic tissues of the spikelets in the senescent phase. Boot ethylene correlated positively with number of barren spikelets in the panicle and negatively with concentration of photosynthetic pigments of the seed coat of inferior spikelets. The concentration of ethylene was higher in the high sterile cultivar Mahalaxmi than that of the low sterile Mahanadi. Inhibition of ethylene action or synthesis improved grain filling. The chemicals were most effective on the inferior spikelets. It was concluded that ethylene retarded seed coat development during the prestorage phase and reduced grain filling of basal spikelets.

The effect of nitrogen and silica nutrition on percentage of sterility by rice plant

pp. 881–889 In order to understand the influences of nitrogen and silicate fertilizer application on anther length and percentage of the sterility of the rice plant, we investigated by field experiment in Hokkaido Kamikawa Agric. Exp. Stn. (Brown Lowland soil) and by air-conditioned room experiment. The results are summarized as follows. 1) Application of silicate fertilizer decreased percentage of sterility. Compared with basal application, topdressing of silicate fertilizer was more effective in increasing carbohydrate content and anther length, decreasing percentage of sterility. 2) The anther length was negatively correlated to percentage of sterility and was positively correlated to carbohydrate content in the rice plant. Similar regression curves were plotted between the field experiment and the air-conditioned room experiment. 3) Silicate content in rice plants was increased at the flag leaf stage by applying both basal and topdressing silicate fertilizer. Furthermore, silicate content was correlated to carbohydrate content. Nitrogen content was negatively correlated to carbohydrate content. 4) Protein content in polished rice was decreased by silicate fertilizer application.

Induced Desynaptic Male Sterile Lines in Soybean

In a study on soybean using gamma rays, we came across with some sterile mutants. Cytological studies of these mutants clearly revealed desynapsis in them. In these sterile plants only few bivalents and a high frequency of univalents have been recorded and they displayed a very high percentage of pollen sterility. Later meiotic stages were also found to be highly disturbed. The plants were identified as male sterile ones as few pods were formed. It might be possible that gamma rays have acted on some genes responsible for synapsis and chiasma formation and resulted in early chiasmate dissociation suggesting that gamma rays can act as a potential tool in the development of male sterile lines. Study of desynaptic mutants is a potentially important source of information on the chiasma maintenance mechanism. These mutants furthermore can provide useful cytological and genetical informations on the male sterility occured in higher plants.

Effect of Growth Regulators and Chemicals on Pollen Sterility in TGMS Lines of Rice

Thermosensitive genic male sterility (TGMS) in rice is a widely adopted technique for successful hybrid rice production in Asia. TGMS lines remain male sterile when daily mean temperature is above the critical sterility temperature and are therefore used as female parents. The same line will remain fertile when mean temperature is below the critical sterility temperature. Achievement of 100% male sterility in TGMS lines is important for the successful utilization of TGMS lines as female parents in hybrid rice production. This study examined the external application of some growth regulators and chemicals and their effect on pollen sterility. Among the various treatments, ethrel (800 ppm), salicylic acid (600 ppm) and maleic hydrazide (0.2%) induced a significantly higher percentage of male sterility in the TGMS lines. The sprayed plants also showed higher total phenol accumulation in their flag leaves. The results suggest that it is possible to achieve 100% male sterility in TGMS lines with the external application of growth regulators and chemicals.

Consequences of Acclimation on Survival and Reproductive Capacities of Cold-Stored Mummies of <I>Aphidius rhopalosiphi</I> (Hymenoptera: Aphidiinae)

The cold storage of parasitoid mummies is a crucial point during mass production of parasitoids for aphid control in wheat, Triticum spp. In this study, the effect of acclimation to cold before storage of mummies containing Aphidius rhopalosiphi DeStefani-Peres (Hymenoptera: Braconidae: Aphidiinae) was evaluated on survival, sterility, and fecundity of parasitoids. Groups of 1-d-old and 3-d-old mummies were stored at -5 degrees C for 10 d without acclimation or after one of five different acclimation treatments. One-day-old and 3-d-old mummies contain prepupa and postmetamorphosis but not yet sclerotinized adult parasitoids, respectively. The offspring and sex ratio of stored parasitoids were compared with a control that was left at rearing temperatures (20 degrees C). Without acclimation, two-thirds of the parasitoids died during storage, for both ages of mummies tested. For stored 1-d-old mummies, subsequent survival increased under progressive exposure to low temperatures and reached 67.3% after 480 min of acclimation. In the same way, percentage of male sterility decreased with acclimation duration, whereas female fecundity increased. For stored 3-d-old mummies, subsequent survival improved with the duration of the acclimation treatment, but not male sterility and female fecundity.

Evaluation of advanced rice germplasm under water stress environment

Thirteen genotypes of rice comprising of approved varieties and elite candidate lines were studied at three different water regimes by supplying 12, 8 and 4 numbers of irrigations at different intervals/ stages. The experiment was conducted at NIAB Farm Faisalabad, Pakistan on a clay loam soil applying normal doses of N and P fertilizers during 2002–2003 keeping varieties in the main plot while treatments in sub plot. The data for twelve morphological characters i.e. days to flower, days to mature, plant height, panicle length, number of productive tillers, number of primary and secondary branches, 1000 grain weight, sterile grains per spike, number of total grains per spike, fertility percentage, grain yield were recorded and subjected to analysis of variance and means were compared following DMR test. Effect of water stress on different morphological attributes in all treatments showed significant differences. Plant height, branches per plant, number of grains and grain yield reduced at less number of irrigations while sterility percentage was increased at less moisture conditions. Maximum grain yield (5349 Kg/ha) was achieved at T1 where 12 number of irrigations were applied at T2 (8 irrigations) and T3 (4 irrigations). The yield reduction was observed from 30.32% to 42.53%, respectively as compared to T1 (12 irrigations). Rice variety DM 64198 produced the highest seed yield (4766 Kg/ha) followed by DM-3-89 (4770 Kg/ha).This might be due to different genetic make up of the breeding lines and their behavior and interaction in water stress environment. Furthermore, high irrigation level made possible the appropriate water availability possible at proper time for performing different types of physiochemical processes of development that hindered at less number of irrigation or water stress environment. It may be concluded that for achieving maximum economic yield, at least 12 irrigations were essential otherwise the production will be reduced to a considerable extent.

The Effect of Nitrogen and Silica Nutrition on Percentage of Sterility by Rice Plant

The Effect of Nitrogen and Silica Nutrition on Percentage of Sterility by Rice Plant

Identification of critical sterility temperature (CST) and thermo sensitive stage in selected TGMS lines in rice (OryZa sativa L.)

Thermosensitive genic male sterility (TGMS) is a type of genetic male sterility expression regulated by certain temperature conditions. The knowledge of the critical sterility temperature and the critical thermosensitive stage for fertility alteration of TGMS lines is useful to determine most suitable time of their planting for multiplication or hybrid seed production. The experiment was conducted in mini phytotron. The critical sterility temperature of three TGMS lines viz. TGMS 6, TGMS 16 and TGMS 29 was assessed by subjecting them to different temperatures during reproductive stage. The pollen sterility percentage increased as the daily mean temperature increased and the genotypes behaved differently before they attain complete pollen sterility. The results that the CST of TGMS 6 was 28.0°C, TGMS 16 was 27.0°C and TGMS 29 was 27.5°C with 34.0, 33.0°C and 34.0°C the maximum temperatures respectively. Three TGMS lines were exposed to CST for different durations coinciding the various stages of panicle development to understand the critical stage of thermosensitivity for fertility alteration. In this study, 10-25 DBH was identified as critical thermosensitive stage for fertility alteration, which corresponds to differentiation of secondary branch primordiam, differentiation of pistil and stamen, formation of PMC and early meiosis stages (Stage 111 to IV).

Effect of a low dose of aluminum on mitotic and meiotic activity, 4C DNA content, and pollen sterility in rice, Oryza sativa L. cv. Lalat

Aluminum toxicity in acidic soils poses a major threat to plant growth and development. The effects of a low dose of aluminum (50 μM, AlCl 3) on various cytological parameters, including mitotic and meiotic chromosomal divisions, in situ nuclear DNA content, interphase nuclear volume (INV), and pollen fertility were compared in untreated (controls) and treated rice plants ( Oryza sativa cv. Lalat). The results showed varied chromosomal abnormalities, including chromosome stickiness, laggards, sticky bridge, occurrence of micronuclei, as well as binucleate and multinucleated cells, as a result of aluminum treatment. Aluminum toxicity also inhibited to a small extent the growth of the rice cultivar Lalat. The mitotic and meiotic indexes, even after a prolonged period of recovery, were significantly low. The chromosomal anomalies in the meiotic cells persisted, and plants exhibited a high percentage of pollen sterility (∼64%). The nuclear DNA content declined markedly from 11.85 pg in the control to 6.30 pg in the treated plants. The INV also varied significantly between the untreated (controls) and the treated plants. The occurrences of different types of chromosomal aberrations, reduction in the amount of nuclear DNA, and persistence of the phytotoxic effects at the post-treatment stage suggest carcinogenic effects of aluminum on rice plants. The presence of aluminum in acidic soils might thus be extremely hazardous and might cause permanent cytotoxic disorder in rice plants.

Soil Boron Deficiency Induced Wheat Sterility in Nepal

ABSTRACT Soil B deficiency is widespread in Nepal, adversely affecting grain yield by inducing sterility in cereal and legume crops. The awareness and acknowledgement of soil B deficiency in Nepal is not as widespread as its occurrence, its deficiency symptoms in plants being largely “hidden.” Crop observations in farmer's field indicated that B deficiency induced sterility in wheat may be influenced by nitrogen management and the climatic conditions prevailing during the crop growing season, though there had not been any field experimental data to support such claim. Therefore, a field experiment was designed at the Naldung rice-wheat site of Kavre district of Nepal to study the effect of B and N on sterility in wheat. Soil application of B at sowing reduced sterility by more than 50% and doubled wheat yields by increasing seed set. Application of N at 16,40,80,120 and 160 kg/ha did not influence percent sterility in wheat. Additional screening trials also indicated significant wheat varietal differences...

Indian Journal of Agronomy 58 (1): 54__62 (March 2013) Research Paper

System of rice (Oryza sativa L.) intensification (SRI) is a recent breakthrough in rice production technology. Tiller-production with healthy panicles, the key determinant of high yields under SRI, is variety and agronomic management dependant. This experiment was laid-out in a factorial RBD during rainy seasons of 2008 and 2009 in the tarai belt of northern India using fourteen treatments comprising of three irrigation schedules viz., irrigation at 1, 3 and 5 days after disappearance of ponded water (DADPW), two spacing intervals (20 cm 20 cm, 25 cm 25 cm) and two varieties (Pant Dhan 4, Arize 6444) under SRI, and two controls consisting of conventional culti- vation (CT) of two varieties. In 2008, irrigation effects were non-significant, while in 2009, irrigation at 1 and 3 DADPW caused 19.338.5% and 9.322%, respectively, higher number of filled spikelets/panicle, and recorded higher panicle weight and lower sterility percentage than 5 DADPW. Overall advantage in grain yield due to irriga- tions at 1 and 3 DADPW was 8.6 and 5.8%, respectively over 5 DADPW (5.82 t/ha). Wider spacing resulted in heavier panicles and higher grain yield than narrow spacing. Between two varieties, Arize 6444 produced higher number of filled spikelets in all type of tillers. SRI improved the panicle characteristics and increased grain yield by 16.9% over CT (5.22 t/ha). Number and weight of filled-spikelets/panicle of primary and secondary tillers were cor- related with grain yield. Under SRI, varieties which produce large number of primary and secondary tillers with heavier panicles and a few or no tertiary tillers should be planted as panicle weights of tertiary tillers did not show significant correlation with grain yield. Further, SRI-rice should be planted at 25 cm 25 cm spacing and irriga- tions should not be delayed beyond 3 DADPW.