Effect of Pre-sowing Treatments on Vegetative Growth and Production of Graftable Rootstocks in Mango

The present investigations “Studies on the effect of pre-sowing treatment and time of wedge grafting on production of saleable grafts in mango” were carried out in the nursery block of Fruit Science Department. The study was conducted using wild mangoes seeds. The seeds were divided in two equal halves, one half of seeds were sown with intact seed coat (K1) while, in other half the mango kernels were extracted (K2), both type of seeds were then soaked in 6 different chemicals of varying concentrations viz. C1- KNO3 @ 0.5%, C2- KNO3 @ 1%, C3- KNO3 @ 1.5%, C4- BA @ 50 ppm, C5- BA @ 100 ppm, C6- GA3 @ 100 ppm, C7- GA3 @ 200 ppm, C8- beejaaumrit @ 2%, C9- beejaaumrit @ 3%, C10- panchgavya @ 2%, C11- panchgavya @ 3% for 12 hours and C12- Control. The germination and vegetative parameters were observed. The results of study revealed that the e×tracted kernels pre-soaked with GA3 @ 100 ppm produced earliest germination, 50 % germination, high rate of germination, germination percentage, number of leaves, maximum leaf area, highest seedling vigour index, while, on pre-soaking extracted kernel with KNO3 @ 0.5% produced maximum seedling diameter. The Seedling raised from extracted kernels pre-soaked in KNO3 @ 0.5% (C1K2) attained graftable diameter within 210 days of sowing. The present investigation was conducted during 2019-2020 at the nursery block of College of Horticulture and Forestry, Neri Hamirpur (H.P) to study the effect of pre-sowing treatments on germination, growth and production of graft-able seedlings.

How bean weevil (Acanthoscelides obtectus, Coleoptera, Bruchinae) larvae die on legume seeds

BackgroundThe host specificity and the range of possible wild and cultivated hosts of the dry bean weevil, Acanthoscelides obtectus (Coleoptera, Chrysomelidae, Bruchinae), a seed predator of beans, is poorly known. In addition, female oviposition preference and larval performance relationship is complicated by the respective importance of seed coat and cotyledon, because, on the one hand, paradoxically, females lay eggs on the basis of stimuli of the seed coat alone, without directly being able to assess the quality of cotyledon’s suitability for larval development. On the other, the thickness of seed coat may prevent first instar larvae from entering the seeds, even if cotyledons were suitable for development.ResultsThe seeds of 62 leguminous species and 82 accessions occurring in Hungary were tested in no-choice tests for egg-laying. The ability of first instar larvae to overcome seed coat, as a physical barrier, was measured with intact seed coat, whereas drilled seed coats allowed assessing the suitability of cotyledon for development. Seeds of 18 species (35% of them Lathyrus) supported larval development to adults, if the seed coat was drilled, however, only nine produced adults, if the seed coat was intact. Seed coats thicker than 0.1 mm could be an obstacle for first instar larvae. There was no overall positive correlation between oviposition preference and larval performance, with the exception of 16 so-called acceptable non-hosts (Kendall’s τ = 0.3088). Bean weevil females also demonstrated an ovipositional hierarchy of legume species even in no-choice tests.ConclusionsResults demonstrate that whereas the use of some acceptable non-host species by the bean weevil is possible in seed stores, the same is unlikely under outdoor conditions, because it requires the recognition of basically different oviposition substrates (pods).

Recalcitrant and orthodoxSpartinaseeds or isolated embryos exhibit similar leachate patterns immediately following desiccation

Solute leakage is used as an indicator of membrane damage during desiccation of recalcitrant seeds. We re-examined this phenomenon and its utility by comparing recalcitrantSpartina alternifloraand orthodoxSpartina pectinataseeds, as well as drying isolated embryos or embryos isolated after whole-seed drying. During drying, intact seed leakage (electrical conductivity and absorbance at 280 nm) was independent of seed moisture content, dormant/non-dormant state or desiccation tolerance. Embryos from bothSpartinaspecies, isolated after drying within the intact seed, exhibited increased leakage, especially below 40% (dry weight basis, DWB) seed moisture, the critical water content for viability loss inSpartina alterniflora. When isolated embryos were dried, the pattern and extent of increased solute leakage were similar in bothSpartinaspecies, even thoughS. pectinataembryos were >95% viable andS. alternifloraembryos were < 20% viable. We conclude that increased solute leakage is an artefact of embryo excision and not an accurate indicator of desiccation damage to recalcitrantSpartina alternifloraseeds.

Trophic eggs compensate for poor offspring feeding capacity in a subsocial burrower bug

Various animals produce inviable eggs or egg-like structures called trophic eggs, which are presumed to be an extended maternal investment for the offspring. However, there is little knowledge about the ecological or physiological constraints associated with their evolutionary origin. Trophic eggs of the seminivorous subsocial burrower bug ( Canthophorus niveimarginatus ) have some unique characteristics. Trophic eggs are obligate for nymphal survival, and first-instar nymphs die without them. To identify the cause of nymphal death, we hypothesized that first-instar nymphs starve to death because they cannot feed on anything but trophic eggs. Although first-instar nymphs fed on artificially exposed endosperm did survive, nymphs that were provided with intact seed were not able to penetrate the seed vessel and starved to death. Another hypothesis that trophic eggs play a role in transferring the midgut symbiont, essential for survival in heteropteran bugs, from mother to offspring was rejected because almost all nymphs had retained the symbiont without feeding on trophic eggs. These results suggest that poor feeding capacity of the offspring is the cause of nymphal death, and the important constraint that promotes the evolution of the curious trophic egg system in C. niveimarginatus .