EjRAV1/2 Delay Flowering Through Transcriptional Repression of EjFTs and EjSOC1s in Loquat

Most species in Rosaceae usually need to undergo several years of juvenile phase before the initiation of flowering. After 4–6 years’ juvenile phase, cultivated loquat (Eriobotrya japonica), a species in Rosaceae, enters the reproductive phase, blooms in the autumn and sets fruits during the winter. However, the mechanisms of the transition from a seedling to an adult tree remain obscure in loquat. The regulation networks controlling seasonal flowering are also largely unknown. Here, we report two RELATED TO ABI3 AND VP1 (RAV) homologs controlling juvenility and seasonal flowering in loquat. The expressions of EjRAV1/2 were relatively high during the juvenile or vegetative phase and low at the adult or reproductive phase. Overexpression of the two EjRAVs in Arabidopsis prolonged (about threefold) the juvenile period by repressing the expressions of flowering activator genes. Additionally, the transformed plants produced more lateral branches than the wild type plants. Molecular assays revealed that the nucleus localized EjRAVs could bind to the CAACA motif of the promoters of flower signal integrators, EjFT1/2, to repress their expression levels. These findings suggest that EjRAVs play critical roles in maintaining juvenility and repressing flower initiation in the early life cycle of loquat as well as in regulating seasonal flowering. Results from this study not only shed light on the control and maintenance of the juvenile phase, but also provided potential targets for manipulation of flowering time and accelerated breeding in loquat.

How much the response of rice genotypes to water deficit at the reproductive phase is dependent from environmental conditions?

Rice crop is known as particularly sensitive to water deficit, especially during the reproductive phase when growth of vegetative organs and formation of spikelets are simultaneous. Many works have focused on the response of rice plants to water deficits varying in timing, duration and intensity. Oppositely, the impact of the environmental conditions on the response to a given water deficit remains largely unknown. In order to test it, two experiments under contrasted conditions of temperature, radiation and VPD were conducted on six genotypes in greenhouse in Brazil (S) and in growth chamber in France (GC). The plants were submitted to the same mild water deficit at the reproductive phase, by adjusting FTSW at 0.4. Under irrigation, plant growth rate was reduced and crop duration extended in GC in relation to S: ultimately, this trade-off resulted in similar plant height and biomass in both environments. Under water deficit and in both environments, elongation rate decreased and was associated with an increase in soluble sugars in stem and flag leaf, while starch was reduced in S and negligible in GC because of the low radiation. This common biochemical response displayed a large gradient of values across environments and genotypes, but differentially impacted the branch and spikelet formation on the developing panicle: in carbon limiting conditions (GC), the increase in soluble sugars was associated with the reduction in branch and spikelet number, and conversely in S. At the morphological level, the maintenance of spikelet number on the panicle was correlated with the maintenance of flag leaf width in all genotypes and conditions, that was discussed according to the maintenance of the apical meristem size. Genotypes were discriminated and the study underlined the global tolerance of Cirad 409 and sensitivity of IAC 25.

Early transplanting of rainfed rice minimizes irrigation demand by utilizing rainfall

Background Rainfall is the key contributor to provide soil moisture for wet season rice (T. Aman) cultivation. Erratic rainfall often causes water shortage resulting negative impact on plant growth and grain yield. The study aimed to determine suitable transplanting window that utilize maximum rainfall for T. Aman rice. Firstly, three years field experiment were conducted in Kushtia, Bangladesh from T. Aman, 2013 to 2015, and then the findings were implemented for another two adjacent locations, Panba and Rajshahi. The field experiment considered six transplanting dates of popular cultivar BR11 (growth duration 145 days) at 7 days interval starting from 10 July to 14 August. The CROPWAT 8.0 model was used to calculate crop water requirement (CWR), effective rainfall and irrigation demand (ID) from collected weather data in each growth phase of rice. Results In all locations T. Aman rice received enormous rainfall up to vegetative phase resulting no irrigation demand in all three tested years. The early transplanting received more rainfall in reproductive phase than late planting. Thus, Irrigation demand increased at reproductive phase with delay transplanting in moderate drought prone Kushtia, Pabna and Rajshahi. A significant relationship (R2 = 0.71) observed between reproductive phase ID and grain yield, while grain yield responded weakly with the ID at ripening phase. Based on yield performance 10–24 July found suitable transplanting window for BR11 in Kushtia. Considering the relationship between ID and grain yield, 10–17 July and 10–24 July considered the best transplanting window in Pabna and Rajshahi, respectively. Conclusions Location specific suitable transplanting windows were selected considering minimum ID at reproductive phase and the maximum grain yield. Delay in transplanting demanded more irrigation and reduced grain yield. Whereas, early transplanting utilized maximum rainfall, reduced ID in reproductive stage and ensured desired grain yield.

Screening of Pigeonpea [Cajanus cajan (L.) Millsp.] Against Tur Pod Bug, Clavigralla gibbosa (Spinola) in Long Duration Pigeonpea Genotypes

The pigeonpea was infested with the number of insect pests at various stage of crop growth. Out of which the incidence pattern of C. gibbosa was studied. The result of the investigation pertaining to the “Screening of pigeonpea [Cajanus cajan (L.) Millsp.] against Tur Pod bug, Clavigralla gibbosa (Spinola) in long duration Pigeonpea genotypes” was carried out in 2018-19 at the Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi. This insect was studied during reproductive phase of the crop during 2018-19. The very first presence of pod bug, [C. gibbosa (spinola)] was reported in all genotypes with a maximum population of (1.13 bug/plant) in the MAL-13 (AVT1) genotype in the 4th standard week pursued in the first week by AVT1-706 (1.06 bug/plant), AVT1-705 (1.03 bug/plant) in first week. Pod Bug population continued between the 4th standard Week of 2018-19. Throughout all genotypes, that 12th standard week Pod bug populations had been reported to also be especially high mostly during 12th standard week for nearly every genotypes. MAL-13 (AVT1) genotypes, accompanied by AVT1-704, would have the highest percentage of 10.55 bugs/plant, as well as 9.62 bugs/plant populations. In genotypes AVT1-707 (4.96 bug/plant), the lowest population of pod bugs was found. AVT2 - 903 (5.02 bug/plant), and AVT1-703 (5.17 bugs/plant) during the 10th standard week. The mean pod bug population was substantially different in different genotypes and ranged from AVT1-708 (1.72 bugs/plant) to MAL 13(AVT1) (3.77 bugs/plant). . Its degree of damage in cultivar AVT2-904 ranged from 27.33% to 51.00% in cultivar AVT1-703. The grain loss in genotype AVT2-904 ranged from 12.68% to 30.52% in genotype AVT2-907.

Physiological and genetic characterization of heat stress effects in a common bean RIL population

Heat stress is a major abiotic stress factor reducing crop productivity and climate change models predict increasing temperatures in many production regions. Common bean (Phaseolus vulgaris L.) is an important crop for food security in the tropics and heat stress is expected to cause increasing yield losses. To study physiological responses and to characterize the genetics of heat stress tolerance, we evaluated the recombinant inbred line (RIL) population IJR (Indeterminate Jamaica Red) x AFR298 of the Andean gene pool. Heat stress (HS) conditions in the field affected many traits across the reproductive phase. High nighttime temperatures appeared to have larger effects than maximum daytime temperatures. Yield was reduced compared to non-stress conditions by 37% and 26% in 2016 and 2017 seasons, respectively. The image analysis tool HYRBEAN was developed to evaluate pollen viability (PolVia). A significant reduction of PolVia was observed in HS and higher viability was correlated with yield only under stress conditions. In susceptible lines the reproductive phase was extended and defects in the initiation of seed, seed fill and seed formation were identified reducing grain quality. Higher yields under HS were correlated with early flowering, high pollen viability and effective seed filling. Quantitative trait loci (QTL) analysis revealed a QTL for both pod harvest index and PolVia on chromosome Pv05, for which the more heat tolerant parent IJR contributed the positive allele. Also, on chromosome Pv08 a QTL from IJR improved PolVia and the yield component pods per plant. HS affected several traits during the whole reproductive development, from floral induction to grain quality traits, indicating a general heat perception affecting many reproductive processes. Identification of tolerant germplasm, indicator traits for heat tolerance and molecular tools will help to breed heat tolerant varieties to face future climate change effects.

Study of the Gametophytic phase of Diplazium caudatum (Athyriaceae, Polypodiopsida) from Spain

The gametophytes of the Athyriaceae are not very well known, such as Diplazium caudatum. The aim of this work is to analyze the gametophytic phase of this species, which includes germination study, morphological development and reproductive phase. Spores belonging to two different sporophytes from La Gomera, Spain, were mixed and sown in multisporic cultures. Plates have been cultured in chambers with nutritive agar at 25ºC and 12 hours photoperiod. The germination was registered every three days, and the main vegetative and reproductive development was checked throughout the observational period. The germination rate reached a maximum of 58%. The spore germination followed a Vittaria pattern meanwhile prothallial development followed an Adiantum type. Regarding sexual expression, all gametophytes developed archegonia and later some of them developed antheridia becoming bisexual.

Early Transplanting of Rainfed Rice Minimizes Irrigation Demand by Utilizing Rainfall

BackgroundRainfall is the key contributor to provide soil moisture for wet season rice (T. Aman) cultivation. Erratic rainfall often causes water shortage resulting negative impact on plant growth and grain yield. The study aimed to determine suitable transplanting window that utilized maximum rainfall for long duration (145 days) rice cultivar. Firstly, three years field experiment conducted in Kushtia, Bangladesh in T. Aman season from 2013 to 2015, and then the findings were implemented for another two adjacent locations, Panba and Rajshahi. The field experiment considered six transplanting dates of popular cultivar BR11 at 7 days interval starting from 10 July up to 14 August. The CROPWAT 8.0 model was used to calculate crop water requirement (CWR), effective rainfall and irrigation demand (ID) from collected weather data in each growth phase of rice. A suitable transplanting window was selected considering minimum ID at reproductive phase and the maximum grain yield. ResultsT. Aman rice received enormous rainfall and accounted no irrigation at vegetative phase in all three tested years in all locations. The early transplanting received more rainfall in reproductive phase than late planting practice. Thus, Irrigation demand increased at reproductive phase with delay transplanting in moderate drought prone Kushtia, Pabna and Rajshah. A significant relationship (R2 = 0.71) observed between ID at reproductive phase to grain yield, while grain yield responded weakly with the ID at ripening phase. Based on yield performance 10-24 July found suitable transplanting window for BR11 in Kushtia. Applying ID vs yield relationship, 10-17 July and 10-24 July considered the best transplanting window in Pabna and Rajshahi, respectively. ConclusionsDelay in transplanting demanded more irrigation and reduced yield. Consequently, early transplanting utilized maximum rainfall, reduced ID in reproductive stage and ensured desired grain yield.