Vertical distribution of some piercing sucking insects on some roselle varieties in Egypt and the role of amino acids concentration in infestation

Abstract

The cotton aphid, Aphis gossypii Glover was found to be the only aphid species infesting the tested roselle varieties (Sudani, Masri and White), Hibiscus sabdariffa L. which were cultivated in El-Kanater El-khayria (about 30 km north Cairo) as ex situ old land. The vertical distribution of the whitefly, Bemisia tabaci (Genn.); the leafhopper, Empoasca spp. and the pink hibiscus mealy bug, Maconellicoccus hirsutus Green, as insect pests attacking this crop had been studied. Moreover, certain morphological characters and amino acids concentrations in the three varieties of roselle, were obtained. The obtained results indicated that the experimental insect pests severely attacked leaves of the stem nodes from the 8th to the 11th (counting from the top of the plant), whereas whitefly were more abundant on these nodes. All tested insect species were less abundant on the 4th stem node. This may be due to the extensive existence of gland hairs, that excrete some compound especially phenols that might prevent the insects from reproducing on the leaves. The opposite was, however, true for M. hirsutus as it did not attack Sudani and Masri varieties but the infestation occurred at the highest level on the White variety.     

Evaluation of infestation percentage of cotton fields to the spiny bollworm,Earias insulana Boisduval (Lep.: Noctuidae), and its relationship with pheromone traps

Spiny bollworm, Earias insulana Boisduval (Lepidoptera: Noctuidae), is one of the most important pest of malvaceous plants throughout the world, except America. In recent years, this insect has been serious pest for cotton fields in southern regions of Iran, especially Darab region of Fars province. In order to evaluate the performance of sex pheromone in reduction of infestation percentage of the spiny bollworm by mass trapping method, an experiment was carried out during year of 2012 in Darab region in Randomised Completely Block Design with six treatments and four replications. The treatments were: application of the four sex pheromone trap densities at the rates of 16, 20, 24 and 30?traps/h, application of Larvin chemical insecticide at the rate of 1?L/h and control. Percentages of infected bolls and flowers to E. insulana were weekly determined. The application of Larvin insecticide performed as the pest population reached to economic threshold level. Analysis variance of results showed that there are significant differences between time, trap number and time?×?trap interaction on infestation percentage per hectare. During sampling time, the highest infestation percentage was in control treatment and the lowest one was observed in 30 and 24?traps/h treatments. The peak of infestation percentage was seen in 18th of November. The best efficiency among treatments was observed in pheromone trap. In conclusion, using sex pheromone trap in comparison to application of insecticides can efficiently reduce infestation level of cotton fields.     

The role of predators and parasites in controlling populations ofEarias insulana,heliothis armigera andBemisia tabaci on cotton in the Syrian Arab Republic

Studies on the relationship between insect pests and their predators and parasites were conducted in the Syrian cotton agro-ecosystem from 1980 up to 1983.Earias insulana (Boisduval) was found to be the most damaging pest, whileHeliothis armigera (Hübner) was not an annual returning problem. Among the entomophagous insects found, coccinellids were most numerous during the months June and July and the hemipterous predators were more abundant during August and September. When predator numbers were reduced with insecticide applications, a significant increase in the bollworm populations occurred, resulting in significant reductions in seed cotton yields. Parasites were relatively not important for the control of lepidopterous pests on cotton. Egg and larva populations ofE. insulana andH. armigera were parasitized byTrichogramma spp. andHabrobracon brevicornis Wesmael respectively. Populations ofBemisia tabaci (Gennadius) were heavily parasitized byEretmocerus mundus Mercet.      

Prevailing insects in Roselle plants,Hibiscus sabdariffa L., and their efficiency on pollination

Field surveys of Roselle plant fields were conducted during two successive seasons of 2006 and 2007. The total counted insects on Roselle, Hibiscus sabdariffa attained 16 species belong to seven insect Orders [(Hemiptera (3 species), Homoptera (1 species), Lepidoptera (3 species), Neuroptera (1 species), Coleoptera (3 species), Diptera (1 species), Hymenoptera (4 species)]. Variable numbers of insects were counted on different Roselle varieties and in the two seasons. The most prevailing insect species were the piercing sucking pests [Empoasca spp.; Spilostethus longulus Dallas; Nezara viridula L. and Oxycarenus hyalinipennis (Costa)] and the predators [Polistes sp., Coccinella undecimpunctata and Scymnus syriacus]. Honeybee (Apis mellifera L.) proved to be the most abundant pollinator, averaging 13, 17, 18 individuals/25double strikes in cultivations of Sudani, Masri and White varieties of Roselle plants during flowering of the first season respectively. Similar results were also obtained in the second season. The highest number of honeybees was recorded around 10 am to midday during the flowering stage for the two seasons. It was obvious that the effects of the two hydrothermal, factors temperature and relative humidity, had slight or negligible effects on the occurrence of insect pollination throughout the two seasons of the study, while statistical analysis of the obtained results showed that the productivity of Roselle plant (mean number of seeds and mean weights of seeds) were significantly affected by pollinators.     

Mating, oviposition and gamma sterilization of the spotted bollworm of cotton, Earias insulana

Mating, oviposition and gamma sterilization of the spotted bollworm of cotton, Earias insulana Boisd., were studied under laboratory conditions. The larvae when reared on natural diet produced adults in the sex ratio of about 1 : 1. The females generally mated once and the duration of mating ranged from 35–345 minutes. Egg laying started 2 days after emergence and continued up to 5 days. A mated female laid on an average 103.4 eggs. The majority of virgin females laid none or very few eggs. The moths lived about a week in the laboratory.Dosages up to 35 kR did not affect adult emergence. Both sexes were completely sterilized at 30 kR. Sterile females laid about 10% as many eggs as the control. Their mating ability and longevity were not less than those of the control at sterilizing doses.

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Zusammenfassung Paarung, Eiablage und Gammabestrahlung von Earias insulana wurden unter Laborbedingungen untersucht. An natürlicher Nahrung gehaltene Larven ergaben Adulte mit einem Geschlechtsverhältnis von 1 : 1. Die Weibchen paarten sich im allgemeinen einmal; die Dauer der Paarung lag zwischen 35 und 345 Min. Die Eiablage begann durchschnittlich zwei Tage nach dem Schlüpfen und hielt bis zu 5 Tage an. Gepaarte Weibchen legten durchschnittlich 103,4 Eier. Die meisten jungfräulichen Weibchen legten keine oder sehr wenige Eier. Bestrahlung der Puppen mit bis zu 35 kR beeinflusste das Schlüpfen der Adulten nicht. Bei 30 kR wurden beide Geschlechter vollständig steril. Sterile Weibchen legten nur etwa 10% Eier im Vergleich zur Kontrolle. Paarungsfähigkeit und Lebensdauer dieser sterilen Tiere waren nicht geringer als bei unbehandelt.

     

Use of Bacillus thuringiensis Toxins for Control of the Cotton Pest Earias insulana (Boisd.) (Lepidoptera: Noctuidae)

Thirteen of the most common lepidopteran-specific Cry proteins of Bacillus thuringiensis have been tested for their efficacy against newly hatched larvae of two populations of the spiny bollworm, Earias insulana. At a concentration of 100 μg of toxin per milliliter of artificial diet, six Cry toxins (Cry1Ca, Cry1Ea, Cry1Fa, Cry1Ja, Cry2Aa, and Cry2Ab) were not toxic at all. Cry1Aa, Cry1Ja, and Cry2Aa did not cause mortality but caused significant inhibition of growth. The other Cry toxins (Cry1Ab, Cry1Ac, Cry1Ba, Cry1Da, Cry1Ia, and Cry9Ca) were toxic to E. insulana larvae. The 50% lethal concentration values of these toxins ranged from 0.39 to 21.13 μg/ml (for Cry9Ca and Cry1Ia, respectively) for an E. insulana laboratory colony originating from Egypt and from 0.20 to 4.25 μg/ml (for Cry9Ca and Cry1Da, respectively) for a laboratory colony originating from Spain. The relative potencies of the toxins in the population from Egypt were highest for Cry9Ca and Cry1Ab, and they were both significantly more toxic than Cry1Ac and Cry1Ba, followed by Cry1Da and finally Cry1Ia. In the population from Spain, Cry9Ca was the most toxic, followed in decreasing order by Cry1Ac and Cry1Ba, and the least toxic was Cry1Da. Binding experiments were performed to test whether the toxic Cry proteins shared binding sites in this insect. ¹²⁵I-labeled Cry1Ac and Cry1Ab and biotinylated Cry1Ba, Cry1Ia, and Cry9Ca showed specific binding to the brush border membrane vesicles from E. insulana. Competition binding experiments among these toxins showed that only Cry1Ab and Cry1Ac competed for the same binding sites, indicating a high possibility that this insect may develop cross-resistance to Cry1Ab upon exposure to Cry1Ac transgenic cotton but not to the other toxins tested.     

Host influence on mating behavior and spermatophore reception correlated with reproductive output and longevity of femaleEarias insulana (Boisduval) (Lepidoptera: Noctuidae)

When mating and oviposition behavior ofEarias insulana were studied in the absence or presence of host or by providing only host odor, in comparison to other treatments host absence caused a delayed and reduced reproductive activity with occasional impairment of egg viability. Presence of host or its odor resulted in a short premating period and a significant increase in mating frequency, number of spermatophores transferred, number of eggs oviposited, and proportion of eggs fertilized. Compared to host odor, host accessibility had a larger impact on insect behavior, indicating the importance of host cantact. Under conditions of host accessibility, there existed a significant and positive correlation between the number of spermatophores received by a female and both the number of eggs she oviposited and her longevity. This indicated a role for male-derived nutrients in the reproduction ofE. insulana.     

Larval growth inhibition of the spiny bollworm,Earias insulana, by some steroidal secondary plant compounds

The effect of 23 secondary plant compounds including a series of steroidal aglycones and glycosides, on larval growth and pupation ofEarias insulana (Boisd.) was investigated. Larvae did not develop when fed on artificial diets containing 0.2% solamargine, solasonine, tomatine, digitonin, saponin, nomilin, lawsone or coumarin. Some growth-retarding activity was found with diets containing 0.2% ajmalicine, capsaicin, quercetin, glycyrrhizin and glycerrhetic acid. The eight compounds highly active at 0.2% were also bioassayed at 0.1, 0.05 and 0.01%: larvae did not pupate when fed on diets containing 0.1% solasonine, tomatine or nomilin, whereas solamargine and coumarin were active even at 0.05%. Preliminary structure-activity relationships were evaluated for the active steroidal glycosides.

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Larvale Wachstumshemmung des ägyptischen Baumwollkapselwurms, Earias insulana,durch einige steroide sekundäre Planzeninhaltstoffe

Zusammenfassung Es wurde die Wirkung von 23, einem künstlichen Nährmedium einverleibten, sekundären Pflanzeninhaltstoffen, unter ihnen eine Reihe steroider Aglucone und Glycoside, auf das Larvenwachstum und die Verpuppung vonEarias insulana untersucht. Larven entwickelten sich nicht in mit 0.2% Solamargin, Solasonin, Tomatin, Digitonin, Saponin, Nomilin, Lawsone und Coumarin versetzten Nährmedien. Auf Medien, die 0.2% Ajmalicin, Capsaicin, Quercetin, Glycyrrhizin and Glycyrrhetinsäure enhielten, war das Larvenwachstum verzögert. Die 8 bei 0.2% hoch wirksamen·Substanzen wurden auch bei 0.1, 0.05 und 0.01% getestet. Die Larven verpupten sich nicht auf 0.1% Solasonin, Tomatin und Nomilin und auf 0.05% Solamargin und Coumarin. Vorläufige Struktur-Wirksamkeit-Beziehungen wurden für die aktiven steroiden Glycoside vorgeschlagen.

     

The relative injuriousness of insect pests of cotton in the Namoi Valley,New South Wales

The sequence and relative injuriousness of insect pests was studied for three successive years in unsprayed cotton of the Namoi Valley. Heliothis punctigera Wallengren, the native budworm, and to a lesser extent H. armigera (Hübner), the cotton bollworm, prevented the setting of full crops by destroying buds and bolls. After setting, high proportions of bolls were injured by Earias huegeli Rogenhofer, the rough bollworm. Incidental damage was caused to seedlings by Thrips imaginis Bagnall, the plague thrips, and lo leaves by Anomis flava Fabricius, the cotton looper, and by Austracris guttulosa (Walker), the spur-throated locust. In commercial crops, pest control must rely on the use of broad-spectrum insecticides: H. armigera is currently resistant to several of these, and has become the principal species in the local population of cotton pests. A number of enviromental features impede the natural control of pests in the southerly areas where cotton is now produced. In comparison to the older dryland cropping practised in central Queensland, a higher yield is necessary to cover the production costs of irrigated cotton; a shorter growing season prevents the plants from compensating effectively for insect damage and the natural enemies of cotton pests are less abundant and less active.     

Varietal susceptibility of certain broad bean seeds to infestation with Callosobruchus maculatus (F.) and Callosobruchus chinensis (L.) (Coleoptera: Bruchidae)

Seeds susceptibility of eight broad bean varieties to Callosobruchus maculatus (F.) and Callosobruchus chinensis (L.) infestation were studied for the first time in free- and no-choice methods in the laboratory of Plant Protection Department, Faculty of Agriculture, Zagazig University. The relation between certain seed physical characteristics and some biological and and infestation parameters of both insects in the two studied methods were evaluated. None of these varieties were resistant to both insects, showing various levels of susceptibility. Biological and infestation parameters were significantly different among varieties except the developmental period. In free- choice method, Giza 3 was the most susceptible variety to both insects, since produced the highest progeny of 246.67 and 75.67 adults and susceptibility index (SI) of 10.25 and 7.42, respectively, while the least susceptible variety was Giza 716. In no– choice method, Nubaria 5 and Sakha 1 were the most susceptible varieties to C. chinensis, while Nubaria 3 and Giza 3 to C. maculatus. Differences between physical characters of varieties were significant. Seed hardness were correlated negatively and seed coat thickness positively with laid eggs, progeny and (SI) of both insects in free-choice method. Also seed coat thickness correlated positively with weight loss and seed damage (%) of C. chinensis and negatively of C. maculatus. To reduce seed losses the cultivation of the least susceptible variety (Giza 716) is encouraged and considered for breeding purposes to avoid insecticide usage.     

Maximizing land utilization efficiency and competitive indices of roselle and cluster bean plants by intercropping pattern and foliar spray with lithovit

To maximize the land utilization efficiency of Hibiscus sabdariffa L. (roselle) and Cyamopsis tetragonoloba, Taub (cluster bean), this experiment was executed successfully at Experimental Farm, Fac. Agric., Zagazig Univ., Egypt during 2018 and 2019 at summer season. Intercropping pattern treatments as main plots (sole planting of each component as control, 1: 2, 1: 3 and 2: 3 of roselle: cluster bean as row ratio, respectively), lithovit as sub-plots (CO2 nano-material) at various rates (0.0, 2.0, 4.0 and 6.0 g/l) as well as their interaction effects were estimated. In addition, from calculating competitive indices, it was clear that, the highest land equivalent ratio (abbreviated as LER), area time equivalent ratio (abbreviated as ATER), land utilization efficiency percentage (abbreviated as LUE%) and relative crowding coefficient (abbreviated as RCC) values 1.24 and 1.12, 1.16 and 1.03, 120.57% and 108.06% as well as 0.82 and 0.41 were achieved by the treatment of intercropping pattern of 1 row of roselle alternating with 3 rows of cluster bean during the 1st and 2nd seasons, respectively. The highest values in this concern were achieved with 1: 3 planting pattern combined with 0.0 lithovit rate in the first seasonas well as 1: 2 planting pattern combined with 6.0 g/l lithovit rate in the second one. Also, the highest values of competitive ratio for roselle (Crr) were achieved by combination between 4.0 g/l lithovit rate under 1: 3 pattern, in contrary, the highest values of competitive ratio for cluster bean (Crc) were recorded by combination between 1: 2 pattern with 2.0 g/l lithovit rate in first season. Regardless of the planting patterns combined with different lithovit rates, aggressivity, based on the results, therewas a positive sign for roselle and a negative sign for the intercropped cluster bean, indicating that roselle was dominant, while, cluster bean was dominated.     

ÉLEVAGE SUR MILIEU ARTIFICIEL SIMPLE DE DEUX NOCTUELLES PARASITES DU COTON EARIAS INSULANA ET SPODOPTERA LITTORALIS

Résumé L'élevage des chenilles de Earias insulana Boisd. et de Spodoptera littoralis Boisd. est réalisé sur un milieu artificiel simple ayant déjà permis d'élever 18 autres espèces de Lépidoptères Noctuidae. Les chenilles d' E. insulana sont élevées individuellement pendant tout le développement; tandis que les chenilles de S. littoralis sont élevées en groupe pendant les premiers stades et individuellement pendant les derniers stades. Respectivement pour chacune des deux espèces, 9 et 25 générations sont réalisées pour les souches qui se sont maintenues le plus longtemps. La technique d'élevage est décrite et les résultats obtenus sur milieu sont comparés à ceux obtenus par différents auteurs dans d'autres conditions d'alimentation. Au cours des générations successives certains critères biologiques sont suivis; les variations enregistrées sont discutées.

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Summary Two tropical noctuids, E. insulana and S. littoralis, important pests of the cotton plant, have been reared on an artificial medium that had already allowed culturing 18 noctuid species of the Trifinae, composed as follows: maize semolina 28 g, wheat germ 7 g, Brewers' yeast 7,5 g, ascorbic acid 1 g, benzoic acid 0,3 g, Nipagine 0,25 g, aureomycin chlorhydrate 0,03 g, agar 5 g and H₂O 170 g.With E. insulana, adults were sequestered in groups of 5 to 8 pairs; for S. littoralis in groups or as single couples. The adults were fed with 30% honey-water.The caterpillars of E. insulana were kept individually throughout development; S. littoratis larvae were reared in groups during the first few instars and then individually in stages 5 and 6.With each of the two species two stocks were cultured resulting in 9 and 8 generations of E. insulana, 25 and 19 for S. littoralis. At 25° the mean duration of larval plus pupal development for E. insulana was 27.1 days for males and 26.5 days for females; for S. littoralis 28.0 days and 26.7 days for the respective sexes.Incorporation of a mixture of salts (Wesson's salts) in the diet made a significant improvement in rearing E. insulana: larval development was reduced about 3 days, while the percentage of newborn larvae reaching adulthood increased.With each generation of E. insulana a loss of vigour became apparent: prolongation of the mean larval plus pupal development, reduction in the number of females mated. Considerations of similar work lead to an explanation due to genetic rather than to nutritional factors. No such phenomenon appeared with S. littoralis, where the harsh effect of consanguinity could be avoided; the importance of the size of the starting population, and the ease with which group cultures could be used let us obtain numerous individuals in each generation.

     

Winter hardiness in trench celery

A total of 51 red and white commercial varieties of trench celery were grown and examined for winter hardiness at the National Vegetable Research Station. Although some plants of most varieties survived the winter, none showed a commercially useful degree of winter hardiness, in that none were marketable after moderate frost. The red varieties had a significantly better survival than the white varieties. In the first season, single plant selections were made from the varieties having both the highest percentage of winter survival and the best agronomic characters. Although some of the progenies derived from these selected plants by self-pollination showed a small increase in winter survival as compared with their parent varieties when both were grown in the second season, no plants of these progenies were sufficiently hardy to remain marketable after moderate frost. It was concluded that none of the varieties tested showed any promise as a source of winter hardiness to be used in a breeding programme, and that selection for one generation from within these varieties did not improve winter hardiness to a useful extent.     

Induction and floral determination in the terminal bud of Nicotiana tabacum L. cv. Maryland Mammoth,a short-day plant

Floral determination in the terminal bud of the short-day plant Nicotiana tabacum cv. Maryland Mammoth has been investigated. Plants grown continuously in short days flowered after producing 31.4±1.6 (SD) nodes while plants grown continuously in long days did not flower and produced 172.5±9.5 nodes after one year. At various ages, expressed as number of leaves that were at least 1.0 cm in length above the most basal 10-cm leaf, one of three treatments was performed on plants grown from seed in short days: 1) whole plants were shifted from short days to long days, 2) the terminal bud was removed and then rooted and grown in long days, and 3) the terminal bud was removed and then rooted and grown in short days. Whole plants flowered only when shifted from short days to long days at age 15 or later. Only rooted terminal buds from plants at age 15 or older produced plants that flowered when grown in long days. Only terminal buds from plants at age 15 or older that were rooted and grown in short days produced the same number of nodes as they would have produced in their original locations while buds from younger plants produced more nodes than they would have in their original locations. Thus, determination for floral development in the terminal bud, as assayed by rooting, is simultaneous with the commitment to flowering as assayed by shifting whole plants to non-inductive conditions.Abbreviations LD long day(s) - SD short day(s) - DN dayneutral     

Diversity and variability in seed characters and growth of Pongamia pinnata (L.) Pierre accessions

A thorough and extensive wild germplasm exploration survey was undertaken and 50 high yielding candidate plus trees (CPTs) of Pongamia pinnata (L.) Pierre from different locations from a latitudinal and longitudinal spread between 12°41′ and 22°E longitude and 77° and 84°40′N latitude covering 11 locations in an area spread of 150,000 km² were collected for evaluating genetic association and variability in seed and growth characters. There were significant differences observed in seed morphology and oil content as was in plant height, and number of branches in the progeny trial. Plant height and number of branches exhibited much higher values of both phenotypic and genotypic variance than observed in the seed characters. Among seed characters oil content exhibited highest broad sense heritability of more than 93% followed by seed length (90.0%). In contrast seed width showed the second highest genetic advance of 5.64% following the highest genetic advance of 10.15% exhibited by oil content. Hierarchical clustering by Ward’s Minimum Variance Cluster Analysis method showed phylogeographic patterns of genetic diversity. K means clustering revealed that trees from different geographic regions were grouped together in a cluster and as were trees from the same geographical area placed in different clusters suggesting that geographical diversity did not go hand in hand with genetic diversity. In addition clustering identified promising accessions with favourable traits for future establishment of orchards.     

Detection of protoplast-derived DNA tetraploid Lisianthus (Eustoma grandiflorum) plants by leaf and flower characteristics and by flow cytometry

Plants of lisianthus (Eustoma grandiflorum (Griesbach)Schinners=Lisianthus russellianus Hook.) were regenerated from protoplasts and grown in pots until flowering. Vegetative and floral characteristics were measured and compared with parent plants. Larger leaves and petals and longer guard cells, sepals and filaments were recorded from protoplast-derived plants suggestive of polyploidy. The nuclear DNA contents of protoplast-derived and parental plants were determined by flow cytometry. Protoplast-derived plants were confirmed as DNA tetraploid by flow cytometry with a DNA index of 1.95. Their nuclear DNA content was measured as 6.33±0.04 pg DNA per 2C nucleus compared with 3.26±0.10 pg DNA per 2C nucleus from parental plants. Polyploidisation induced during protoplast regeneration offers an alternative to that of colchicine treatment.     

Inheritance of resistance against northern leaf blight of maize using conventional breeding methods

Maize (Zea mays L.) is one of the important cereal crops along with wheat and rice worldwide. The purpose of this study was to use classical genetic approaches to assess the resistance of various maize parents and hybrids to the northern corn leaf blight (NCLB) disease in two different locations in Egypt. Eight parents, 28 F1, and 2 check hybrids were evaluated. The analysis of variance showed high significant variations between maize parents and their hybrids for the studied parameters and NCLB disease, besides there are significant variations between both locations. Results of maize parents showed that Sids 63, Giza 602, and Giza 628 cultivars exhibited the highest values and were resistant to NCLB in both locations comparing with Nubaria 39 and Gemmiza 18 that were susceptible to NCLB disease. Concerning the maize hybrids, analysis of variance and mean squares of growth characters in both locations indicated high significant variations between the maize hybrids including the check hybrids. When combined between the two locations for current parameters against NCLB, the data pointed that the Sakha location values for maize hybrids were much closed to the combining data in parents and the hybrids detected high resistance to this disease comparing with Nubaria location. All tested maize lines (38 lines), including parents and hybrids were classified as follows, two lines were rated as 1 (highly resistant), three were rated as 2 (resistant), sixteen were rated as 3 (moderate resistant), eight were rated 4 (moderately susceptible) and nine were rated 5 (susceptible). The data explaining that the crossing between high resistant maize cultivars produced high levels of resistance to NCLB disease. Therefore, our results verified that classical breeding could efficiently increase the resistance levels of maize germplasm against NCLB disease by developing new cultivars with superior performance in terms of grain yield, disease resistance and grain quality.     

The influence of parental genotype on the chromosome behaviour of Hordeum vulgare X H. bulbosum diploid hybrids

Summary The PMCs of 74 diploid hybrids involving ten H. vulgare varieties and three H. bulbosum lines were analysed at metaphase I and chromosome number and chiasma frequency recorded. There were differences between parental combinations and between plants within those combinations for both chromosome and chiasma number. It is suggested that these characters are controlled by both parents and that differences between plants within families reflect the heterozygosity of the H. bulbosum parents. Chromosomally stable, high pairing lines have been identified for use in a backcrossing programme to introduce H. bulbosum characters to the H. vulgare germplasm.     

Effect of different organic manures/composts on the herbage and essential oil yield of Cymbopogon winterianus and their influence on the native AM population in a marginal alfisol

Four organic amendments: leaf compost (LC), vegetable compost (VC), poultry manure (PM) and sewage sludge (SSL) applied at four doses (40, 80, 100 and 120 tha(-1)) were evaluated for their effect on the herbage yield, essential oil content and inoculum potential (IP) of native arbuscular mycorrhizal fungi (AMF) on three varieties of Java citronella, Cymbopogon winterianus Jowitt (Manjusha, Mandakini, and Bio-13). PM applied at 100 t ha(-1) followed by SSL increased the herbage, essential oil content and dry matter yield significantly. Bio-13 performed better and produced the highest herbage, essential oil and dry matter yield. The type and dose of the various organic amendments also significantly influenced the indigenous AMF infectious propagules in soil. Highest number of AMF propagules were recorded in the LC amended plots in all the three varieties. Amongst the varieties, highest native mycorrhizal inoculum was recorded in the Bio-13. Least number of AM infectious propagules were recorded in the Mandakini plants grown in 40 t ha(-1) SSL.     

Effect of amino acids on root-knot nematode (Meloidogyne javanica) infecting tomato plant

Six amino acids viz. DL-methionine, DL-valine, DL-serine, DL-phenylalanine, L-proline and L-histidine were tested against root knot of tomato caused by Meloidogyne javanica. All amino acids showed significant response in plant growth characters with corresponding reduction in the number of galls, adult females, egg masses and juvenile stages within the treated plants. DL-phenylalanine gave significantly higher response in reducing the hatch of egg masses and survival of juveniles in in vitro test compared to control. The highest plant growth and maximum reduction of galling incidence of tomato were recorded in the DL-phenylalanine- treated plants followed by L-proline and L-histidine. All the amino acids gave positive response in suppressing the development of the nematode in the treated plants.