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Core collections are the integral part of biotechnology-aided modern-day crop improvement programmes and utilized for a variety of applications including conventional plant breeding, association mapping, resequencing, among others. Since their advent, determination of core collection size has been based on the size of the whole collection. In this study, we precisely estimated the size of the core collection based on the diversity of the whole collection using the Similarity Elimination method. For each of the elimination cycle, allele retention and pairwise and mean genetic distances were calculated and used as the criteria for the precise estimation of the core collection size. We sampled a coconut core collection with 266 entries by retaining the diversity of the whole collection. During the elimination process, accessions with very rare alleles were eliminated first when compared with those having rare and common alleles. Therefore, our results support the hypothesis that the less frequent alleles seldom contribute to the genetic distance when compared with common alleles. In conclusion, presize can be efficiently utilized in any crop for the precise estimation of core collection size. [ABSTRACT FROM AUTHOR]

Silkworm diseases spread during the rearing through various means depending upon the pathogen. When large number of silkworms is reared in the rearing tray, as a routine practice and if some larvae are infected by disease, they extrude the pathogens by various means into the rearing environment to form the source of contamination and spread of disease. The pathogens are extruded by infected silkworms along with gut juice (most viral diseases and pebrine), faecal matter (pebrine and bacterial diseases), breakage of integument (nuclear polyhedrosis and septicemia diseases) and body surface (muscardine and aspergillosis diseases). The diseased larva/moth/ other insects is a source of infection. The pathogens are stable, persist for longer periods in the rearing environment and with efficient mode of dispersal they contaminate the silkworm population leading to secondary infection during the rearing. Several authors have studied the rate of spread of different diseases in silkworm rearing. The spread of pebrine (Ichikawa, 1935; Ishihara and Fujiwara, 1965; Baig etal., 1988), nuclear polyhedrosis (Anonymous, 1990), infectious flacherie (Ishikawa and Miyajima, 1964), densonucleosis (Miyajima, 1979) and bacterial flacherie (Samson, 1987) in the silkworm population were studied by introduction of diseased larvae as carriers. High rate of multiplication and spread are the main characteristic of the fungal diseases in silkworm and white muscardine develops into an epizootic within a short period, if the conditions are congenial, Prabhakaraet al. (1997) studied the rate of spread of white muscardine disease in a silkworm population after introduction of white muscardine larvae during all the larval instars. [ABSTRACT FROM AUTHOR]

Six varieties of spun yarn viz 100% pure wool, 70:30 Wool: Red Eri, 50:50 Wool: Red Eri, 40:60 Wool: Red Eri 30:70 Wool: Red Eri and 100% Eri, blended spun yarn were produced in a spinning mill and the same yarn samples were used for producing fabric samples on power loom. Further the yarn and fabric samples were analysed for shrinkage properties following standard testing methods. Test results were compared with the blends of yarn and fabric. The results of the investigation are discussed. The out come indicates that blending composition of Eri silk with wool fibre has significant effects on the shrinkage properties of yarns and fabrics. [ABSTRACT FROM AUTHOR]

Genotype-environment (G-E) interaction and stability parameters were analyzed for ten each of oval and dumb bell silkworm bivoltine breeds reared during three different seasons of the year. Quantitative economic traits viz., fecundity, cocoon yield /10000 larvae by number, cocoon yield /10000 larvae by weight, single cocoon weight, single shell weight, cocoon shell percentage, filament length, denier, raw silk percentage, renditta, neatness and boil-off loss were evaluated. The mean sum of squares (MS) for the breeds and environments was highly significant (p < 0.01) in both oval and dumbbell breeds in respect of all the traits except for renditta clearly indicating substantial variation among the breeds and seasons. However, the Genotype Environment interaction was found to be nonsignificant for all the traits among oval breeds, while among the dumbbells, only four traits, namely, cocoon yield /10000 larvae by number, cocoon yieId/10000 larvae by weight, filament length and neatness showed significant G E interaction. Two stability parameters, viz., regression coefficient (bi) and deviation from regression (s2di) were analyzed in both oval and dumbbell breeds, which showed significant differences for most of the traits. Based on the values of the two stability parameters for the 12 economic traits and cumulative ranking, CSR2, JPN8 among oval breeds and CSR16 among dumbbell breeds were found to be stable breeds in the expression of quantitative traits irrespective of the seasons, while, S5 (oval) and BBE267 (dumb-bell) expressed less stability. [ABSTRACT FROM AUTHOR]

Silkworm and silkworm faecal matter have long been used in China and Korea as a folk remedy for the treatment of diabetes. It is proved that silkworm powder has blood glucose-lowering effects and effectively inhibits alfa-glucosidase in the human small intestine. In the present study DNJ content measured in mulberry V1 and found highest in medium leaves 302.93 /μg/mg whereas, highest DNJ content was quantified in powder prepared from fed CSR2 × CSR4 larvae of V instar, contain highest on III day 996 μg/mg. Powder prepared from fed larvae of all the days contains significantly more DNJ than starved larvae. Bivoltine fed hybrid larvae DNJ gradually decreased from 3rd day to 5th day of V instar as larvae advanced towards spinning, whereas, in multi x bi though DNJ content was highest on 3rd day of V instar, it decreased on 4th day and then again on 5th day. Hence, silkworm powder has 3-4 times higher DNJ content than mulberry leaves, which can be considered as promising Complementary and Alternative Medicine (CAM) agent in India and can be effectively exploited in future. [ABSTRACT FROM AUTHOR]

Seed germination and seedling growth are influenced by the toxic metabolites produced by pathogenic fungi. Mulberry root rot caused by Rhizoctonia bataticola is one of the major soil borne disease leading to the death of the plants with in a short period of infestation. Two strains R2 and R3 isolated from root rot infested mulberry roots, pure cultures were maintained on PDA slants for further study. CCF at 5, 10, 25, 50, 75 and 100 per cent concentrations were tested on seed germination and seedling growth on 7"' and 21st day respectively. Culture filtrates of both strains inhibited the seed germination, shoot and root elongation at all concentrations. At 100% CCF both strains completely inhibited the seed germination. At 75% CCF R3 strain inhibited the germination up to 89.65 % over control and R2 was totally inhibited. At 50 % CCF 93% and 82.75% inhibition was observed in R2 and R3 stains respectively. The minimum inhibition of seed germination was observed at 5% CCF of both strains. Similarly, the shoot and root elongation was inhibited by both strains at all concentrations of CCF and the inhibitory effect was more on root length than shoot. The percent seed germination and shoot and root growth was inversely proportional to the increase of CCF percentage. The present investigation revealed that the CCF of both the strains oiRhizoctonia bataticola which inhibited the mulberry seed germination and seedling growth, may be due to the release of metabolites polygalacturonate, transeliminase and pectin methylesterase in to the CCF. [ABSTRACT FROM AUTHOR]

In order to suppress soil borne pathogens from contaminated soils to raise disease free mulberry plantation, studies were conducted in plots infested with pathogens causing nursery [Stem-canker (Botryodiplodia theobromae), cutting rot (Fusarium solani), collar rot (Phoma sp.) and die-back (B. theobromae)], root rot (Fusarium solani, F. oxysporum, B.theobromae, Macrophomina phaseolina) and root knot (Meloidogyne incognita) diseases. Different treatments such as deep digging, soil solarization, application of neem oil cake and growing of Dhaincha (Sesbania aculeata) crop alone and their combinations were imposed. Population of pathogens was assessed at 10 days interval up to 80 days after imposing treatments. Complete suppression of population of all the pathogens was observed after 80 days in the combined treatment where deep digging (30 cm), application of neem oil cake (@ 800 kg/ha after 45 days) and raising & mulching of Dhaincha (@ 20 kg seeds/ ha 6 days after neem oil cake application) crop was done. When the new plantation was raised after 80 days of imposing the treatment, all the plants were survived and found free from soilborne diseases besides increasing plant height (32%) and leaf yield (35.0 %) over untreated control. [ABSTRACT FROM AUTHOR]

Fluorescent Pseudontonas and Bacillus are considered to be the most promising group of Plant Growth Promoting Rhizobacteria (PGPR), which are also involved in biocontrol of many plant diseases. In view of exploring potential of these microorganisms as mulberry growth promoters and disease control agents, effect of biopriming with nine strains of fluorescent Pseudontonas (Pf-1 to Pf-9) and Bacillus subtilis (Bs) on the seed germination and seedling growth of mulberry was studied. Significantly (P<0.05) higher germination (99.02%) was found when the seeds were bioprimed with B. subtilis followed by Pseudontonas fluorescence (97.50%) strain Pf-9 and Pf-2. However, the vigour index was found higher (368.6) due to biopriming with Pf-4. Compared with control, the mean total length of the seedling was found higher (11.48%) when the seeds were bioprimed with strain Pf-2 in the in vitro germination study. Similarly, study using strile soil showed higher shoot length due to biopriming with Pf-2 and Bs. These strains showed increase in mean total length 12.58% and 3.89% respectively over the control. Antagonistic effect of various plant growth promoting rhizobacteria to Rhizoctonia bataticola a root rot causing fungus showed significantly (P<0.05) less radial growth towards all the bacteria compared with the control (39.88 mm). The radial growth of R. bataticola was least in presence of Bs, Pf-2, Pf-4 and Pf-6 (11-13 mm). The study suggests exploration of effective native antagonistic PGPR for mulberry growth as well as for root rot disease control. [ABSTRACT FROM AUTHOR]

The results of a survey to investigate the diversity of weed flora of mulberry garden in southern Tamil Nadu (Tirunelveli district) under irrigated condition are described and details of weed species including common and vernacular names, relative density (%), family abundance (number of species/family) and their life form percentage are given. Total numbers of 27 weed species were recorded from 26 genera and 15 families. Among these weed species the relative density was recorded highest with Cyperus rotundus (18.9%) followed by Trianthema portulacastrum (15.2%), Cynodon dactyl one (10.3%), Tridax procumbens (9.4%), Acalypha indica (6.6%), Parthenium hysterophorus (5.8%), Tribulus terrestris (4.9%), Dactyloctenium aegyptium (4.1 %) and Euphorbia hirta (3.65%). The dominant families were Poaceae and Amaranthaceae contributed 4 species each followed by Asteraceae and Euphorbiaceae (3 species each) and Cyperaceae and Malvaceae (2 species each). Most of the species recorded were annual (63%) followed by annual perennial (22%) and perennial (15%). [ABSTRACT FROM AUTHOR]

The organisms that establish positive interactions with plant roots and exhibit observable benefits on the plant growth arc collectively termed as plant growth promoting bacteria (PGPR). They are naturally occurring soil microorganisms, which colonize roots and stimulate plant growth. Such bacteria have been applied to a wide range of agricultural species for the purposes of growth enhancement including increased seed emergence, plant weight, crop yields and disease control. Several chemical changes in soils are fully associated with these bacteria in which some bacterial strains directly regulate plant physiology by promoting synthesis of plant hormones, whereas others increase mineral nutrients availability in the soil as a way to augment growth and development. Beneficial effects of PGPR by its supplemental application to crops or soil were first reported from the former Soviet Union in 1950 and later in Western countries. PGPR were initially applied, to enhance crop fertility by increasing the amount of available N and thereafter were used as biological control agents for suppression of soil borne pathogens. Since 1980 onwards, PGPR have been popular in China and India and referred as yield-increasing bacteria (YIB) followed by biofertilizers in India. [ABSTRACT FROM AUTHOR]

The objective of this breeding study was to develop and identify superior bivoltine breeds possessing the desired targeted traits on productivity along with higher survival under the varied and fluctuation climatic conditions of West Bengal. Initially bivoltine breeds collected from different parts of the country were screened under the ambient conditions of West Bengal. The breeds with high survival with moderate productivity traits were selected as potential parents for this study. By utilising these parental breeds foundation crosses (both ovals and dumbbells) were made and subjected for evaluation under the ambient conditions of West Bengal. Based on the overall performance few oval and dumbbell foundation crosses were identified. [ABSTRACT FROM AUTHOR]

The bulk of silk produced in India is from Multivoltines which are of inferior quality. Therefore, it is highly pertinent to have more productive bivoltine silkworm breeds capable of producing quality silk. However, the hot climatic conditions of India is not conducive to rear productive bivoltines. It is a well established fact that the bivoltines are highly vulnerable to high temperature coupled with high and low humidity especially in the late instars. The hot climatic conditions of tropics prevailing particularly in summer are contributing to the poor performance of the bivoltine breeds and the most important aspect is that many quantitative characters such as viability and cocoon traits decline sharply when temperature is high. Therefore, it is highly pertinent to identify more number of bivotine breeds which can withstand adverse climatic conditions. Accordingly, the present study was carried out to select suitable bivoltine breeds to be used as breeding resource materials for the development of bivoltine silkworm hybrids suitable to West Bengal conditions of India. [ABSTRACT FROM AUTHOR]

The Indian sericulture industry is beset with many problems. One of the main problems is the inability to produce quality silk of international grade. The quality silk can be produced only form bivoltines. The bulk of silk produced in India is from Multivoltines which are of inferior quality. Therefore, it is highly pertinent to have more productive bivoltine silkworm breeds capable of producing quality silk. However, the hot climatic conditions of India is not conducive to rear productive bivoltines. Hence, there is an urgent need to develop bivoltine breeds which can yield stable crops under the adverse climatic conditions. Accordingly, efforts should be focussed by the silkworm breeders to develop bivoltine breeds with genetic plasticity to buffer against the adverse climatic conditions. The main constraint of the tropical environment is the high temperature coupled with high and low humidity. It is a well established fact that the bivoltines are highly vulnerable to high temperature coupled with high and low humidity especially in the late instars. The hot climatic conditions of tropics prevailing particularly in summer are contributing to the poor performance of the bivoltine breeds and the most important aspect is that many quantitative characters such as viability and cocoon traits decline sharply when temperature is high. Therefore, it is highly pertinent to identify more number of bivotine breeds which can withstand adverse climatic conditions. Accordingly, the present study was carried out to evaluate and identify suitable bivoltine breeds under West Bengal conditions of India. [ABSTRACT FROM AUTHOR]

Cocoon crop stability with sustainably good performance is a prerequisite to introduce bivoltine races in a tropical country like India under high temperature and humidity stress. Considering the poor performance of productive bivoltine hybrids during summer season, emphasis was given to evolve bivoltine silkworm breeds suitable to tropical conditions for achieving the primary objective of establishing bivoltine sericulture with quality raw silk among sericulturists. In India, it is not conducive to rear highly productive bivoltine hybrids, especially in summer. Therefore, attempts are being made to develop bivoltine silkworm hybrids tolerant to high temperature situations of the tropics. Attempts made earlier on these lines had resulted in the development of robust bivoltine hybrids viz., CSR18 x CSR19, CSR46 x CSR47 and CSR50 x CSR51. However, these hybrids could not make any impact in Indian sericulture industry. Keeping this in view, attempt is being made here to develop bivoltine double hybrid tolerant to high temperature and high humidity conditions of the tropics. The breeding process as well as the comparative performance of the new hybrid with the already developed double hybrid is also discussed in detail. The study has resulted in the development of bivoltine double hybrid tolerant to high temperature and high humidity conditions of the tropics. [ABSTRACT FROM AUTHOR]

Rapaya mealybug, Paracoccus marginatus Williams Granara de Willink (Hemiptera: Pseudococcidae) is a polyphagous alien pest reported to infest over 80 plant species in India including number of agricultural and horticultural crops, ornamental plants, trees and weed species (Selvaraju and Sakthivel, 2011). Mulberry (Morus alba L.), the food plant of silkworm (Bombyx mori L.) is highly susceptible to this pest and its continued menace in Tamil Nadu after outbreak in 2009, poses threat to sericulture throughout the year (Sakthivel, 2013). The pest feeds on phloem sap of mulberry plants both from stem and leaf resulting in loss of moisture and decline in nutritional values. Growth of dense black sooty mould on leaves over the honey dew excreted by the pest makes them unfit to feed silkworm. Feeding papaya mealybug affected mulberry leaves adversely affects the economic traits of silkworm and silk yield (Sakthivel et al. 2011). Number of weed species in mulberry garden serves as alternate host to the papaya mealybug. From these weeds, the pest easily migrates to the new sprouts after each pruning and build up its population heavily on plant maturity (Sakthivel et al. 2012) which renders repeated incidence. Therefore, identification of weed species harbouring the papaya mealybug population in mulberry ecosystem could help to draw proper management strategies to prevent shifting of this pest from weeds to mulberry and vice versa. Occurrence of papaya mealybug on weed flora in mulberry garden was thus examined in monthly intervals by visual observation in three districts of Tamil Nadu viz Salem, Namakkal, Dharmapuri, [ABSTRACT FROM AUTHOR]