Effect of the Growth Promoter VIUSID Agro on the Morphophysiological and Productive Performance of Tobacco Growth(Nicotiana tabacum L.)

With the objective of evaluating the effect of VIUSID agro on the morphophysiological and productive performance of tobacco seedlings,a randomised block experiment was designed with five treatments and three replications.The variants were:dosage of 0.2,0.5,0.7 and 1.0 L/ha and one control.The variables are recorded at three points of the cultivation cycle 10th,20th and 30th days after planting(DAP).Among the indicators evaluated were the fresh and dry mass of the plants,the leaves per plant,foliar area,the length and diameter of the stalk as well as the characteristics of the root.The rates of physiological growth and agricultural yield were also evaluated.The results showed a significant increase(p≤0.05)in the fresh and dry mass of the plants when VIUSID was used.Regarding the length of the stalk,the average increases of those treated in comparison to the control in the final evaluation were 28.42%,30.51%,41.17%and 38.43%.In terms of the diameter of the stalk and the foliar area in all evaluations,the treatments with VIUSID significantly exceeded the control.The absolute growth rate and net assimilation was significantly higher when the product was used.In the relative growth rate,the most favourable behaviour was the dosage of 0.5 L/ha,in final evaluation.With regard to yield,the best performance with significant differences(p≤0.05)to the other treatments was the dosage of 0.5,0.7 and 1.0 L/ha.Therefore,VIUSID agro had a positive influence on the morphophysiological and productive indicators of the tobacco seedlings.

Effects of desiccation of seeds in nine species with morphophysiological dormancy on germination and embryo growth

Aims In species with morphophysiological seed dormancy(MPD),little is known about the effects of desiccation of imbibed seeds on embryo growth and germination.We studied seed responses to dehydration in nine species with different levels of MPD.Methods For each species,a control test was conducted by keeping seeds permanently hydrated and exposed to the optimal stratification-incubation sequenee to promote embryo growth.Simultaneously,tests were run in which seed stratification was interrupted for 1 month by desiccation at room temperature.Important Findings In Clematis vitalba and Ribes alpinum,with non deep simple MPD,desiccation affected neither embryo growth nor seed viability,but the desiccation led to a decrease of germinative ability in R.alpinum by 16%.The seeds of Narcissus pseudonarcissus subsp.munozii-garmendiae,with deep simple epicotyl MPD,tolerated desiccation in different embryo growth stages,but their germinative ability decreased slightly.The response of species with complex levels of MPD to desiccation was more variable:Delphinium fissum subsp.sordidum,with intermediate complex MPD,and Anthriscus sylvestris and Meum athamanticum,both with deep complex MPD,tolerated desiccation.In contrast,Ribes uva-crispa with nondeep complex MPD,Lonicera pyrenaica with intermediate complex MPD and Chaerophyllum aureum with deep complex MPD,had diminished germination ability by desiccation.Although seeds of the species with simple levels of MPD tolerated desiccation,those of some species with complex levels were also highly tolerant.Thus,desiccation did not induce secondary dormancy in late embryo growth stages.The desiccation tolerance of imbibed seeds of most of the nine species may show their adaptability to climate change in the Mediterranean region.

Temporal transcriptomics reveal the molecular mechanism of dormancy and germination regulated by temperature in Paris polyphylla seed

The mature seed of Paris polyphylla var.chinensis(PPC)is morphophysiologically dormant and develops differently under warm and cold temperatures.To elucidate the molecular mechanisms underlying temperature-dependent regulation of PPC seed dormancy and germination,we investigated the dynamic changes in PPC seed transcript levels under warm and cold temperature stratifications(WS and CS,respectively)by time-resolved RNA sequencing,focusing on genes related to hormone metabolism and signaling and cell wall remodeling(CWRM)and encoding transcription factors/regulators(TFs/TRs).A total of 48765 and 47836 differentially expressed genes(DEGs)were associated with WS and CS,respectively.Of these,17581 and 16652 DEGs,respectively,unique to WS and CS,and 5386 were common to both temperature stratifications across nine analyzed growth stages.The expression of hormone metabolism and signaling,TF/TR,and CWRM genes were closely associated with temperature.More genes related to gibberellin(GA),cytokinin,auxin,and brassinosteroid biosynthetic were upregulated in WS as compared to CS seeds,while genes related to dormancy release and germination were downregulated in WS seeds.However,only GA and abscisic acid levels were altered in PPC seeds breaking morphophysiological dormancy(MPD).Overall,37 TF and five TR families were upregulated whereas 24 TF and 16 TR families were downregulated in WS as compared to CS seeds.Most CWRM families were highly expressed under WS as compared to CS,suggesting that they promote endosperm weakening and embryo growth of WS seeds and facilitate MPD release and germination.A coexpression analysis revealed positive correlations between TFs/TRs and DEGs involved in hormone metabolism and signaling and CWRM.These results provided a basis for investigating the interaction between the endosperm and underdeveloped embryo in the regulation of PPC seed germination and seedling emergence.

Efficient, Season-Independent Seed Germination in Black Cohosh (<i>Actaea racemosa</i>L.)

Seed germination in black cohosh was systematically examined in eighteen populations including 15 USDA accessions with an effective protocol for the consistent, season independent germination of this valuable alternative specialty crop. Two in vitro approaches were investigated for breaking the complex double dormancy of black cohosh seeds for yearround germination of plants for increased cultivation and laboratory studies. The first approach was a two-step alternating temperature stratification in which surface sterilized seeds were incubated in darkness at 25?C for two weeks followed by incubation at alternating temperatures of 20?C and 8?C for 12-hour periods with a 16-hour photoperiod for 12 months. The second was a three-step-approach that involved initial stratification of seeds in darkness at 25?C for two weeks, followed by incubation at 4?C in darkness for 3 -4 months and then cultivation at 25?C with a 16-hour photoperiod to generate seedlings. Although both approaches broke double dormancy for black cohosh seed germination, the three-step-stratification technique yielded higher percentage seed germination in less time when compared to the two-step scheme, including for seeds stored over two years. Additional factors of critical importance for efficient germination included the selection of healthy and viable seeds, as well as thorough but non-excessive surface sterilization to control bacterial and fungal contamination. The in vitro approach for black cohosh germination allowed year-round cultivation and culture of a number of different genotypic accessions to enable laboratory based studies on cell culture and transformation approaches to aid in deciphering gene-metabolite relationships in this important medicinal plant.

The Mechanisms of Trichoderma Species to Reduce Drought and Salinity Stress in Plants

Environmental stresses caused by climate change have severely affected agriculture in the present century;Salinity and drought have challenged most forecasts for increased agricultural production in the past few decades,there-fore,different methods that reduce the effect of these stresses on plants have attracted scientists’attention.The effect of beneficial soil microorganisms on soil health and increasing plants’resistance to stresses is one of the solutions that researchers have paid attention to.This study investigated how Trichoderma species can be affected by the molecular and morphophysiological mechanisms of plants and improve their salt and drought resistance.This study also studied the different Trichoderma species’functions to get a better understanding of how they reduce salt and drought stresses.Furthermore,thefindings of this study provide a clear path for future research to focus on the unknown aspects of Trichoderma species andfind effective ways to boost crop production under environmental stresses.

Discovering the type of seed dormancy and temperature requirements for seed germination of Gentiana lutea L.subsp.lutea(Gentianaceae)

Aims There are a number of mechanisms that regulate germination;among these,seed dormancy,one of the most important,is an adaptative mechanism in plants to promote survival by dispersing germination in space and time until environmental conditions are favourable for germination.The main goals of this study were to determine the tem-perature requirements for seed dormancy release and germination of Gentiana lutea subsp.lutea,to identify the class and level of seed dormancy and to suggest an optimal germination protocol.Methods Seeds belonging to two different localities were subjected to vari-ous pre-treatments,including cold stratification(0 and 5°C),warm stratification(25/10°C)and different combinations of these,and then incubated at a range of constant temperatures(5-25°C)and 25/10°C.Embryo growth during pre-treatments and incubation con-ditions were assessed at different times by measuring the embryo to seed length ratio(E:S ratio).The final germination percentage(FGP)and the germination rate(t50)were calculated.Important Findings Fleshy mature seeds of G.lutea subsp.lutea have linear under-developed embryos.Cold stratification at 0°C was effective in overcoming the physiological dormancy(PD)and promoted embryo growth and subsequent germination.After cold stratifica-tion at 0°C,both the root and the shoot emerged readily under a wide range of temperatures.G.lutea subsp.lutea seeds showed an intermediate complex morphophysiological dormancy(MPD).As regards the optimal germination protocol for this taxon,we suggest a period of cold stratification at ca.0°C followed by seed incuba-tion at 10-20°C.The optimal germination temperatures found for seeds of this taxon,as well as its pre-chilling requirement at 0°C,suggest that it is well adapted to a temperate climate;this behavior highlights an increasing threat from global warming for G.lutea,which could reduce the level of natural emergence in the field,prejudicing also the long-term persistence of the natural popula-tions in Sardinia.