Cercetări privind îmbunătăţirea sortimentului de cais

În articol sunt prezentate unele rezultate privind manifestarea particularităților specifice ale sortimentului de cais local și cel introdus în ultimul timp în condițiile pedoclimatice ale Republicii Moldova. Cele mai favorabile caracteristici țin de adaptabilitate, unități „chilling units” înalte, autocompatibilitate, productivitate sustenabilă și calități înalte ale fructelor.

Sugar units, not chilling units, control endodormancy duration in plants; potato tuber as a case study

Endodormancy (ED) is a crucial stage in the life cycle of many perennial plants, regulated by genetic and environmental factors. Chilling units, growth regulators, and nutrient supply are considered inducers of ED release, but the mechanism governing ED duration is poorly understood. The potato tuber has been used as a model system to study metabolic processes associated with ED release. Cold-induced sweetening is a well-known response of the tuber to chilling. Here, we found that cold stress induces an increase in sugar units in association with plasmodesmatal closure in the dormant bud cells. Tuber sweetening was associated with shortened ED duration after cooling. Heat exposure also caused sugar unit accumulation followed by faster ED release. A logistic function was developed to predict ED duration based on sugar unit measurements. We discovered that ED release is better correlated with the accumulation of sugar units compared to chilling units. CRISPR/Cas9 knockout of the vacuolar invertase gene (StVInv) induced longer ED, but only in cultivars in which the mutation modified the level of sugar units. Our results suggest that sugar units are better predictors of vegetative bud ED duration than chilling units.

Shifts in the thermal niche of fruit trees under climate change: the case of peach cultivation in France

Climate influences plant phenological traits, thus playing a key role in defining the geographical range of crops. Foreseeing the impact of climate change on fruit trees is essential to inform policy decisions to guide the adaptation to new climatic conditions. To this end, we propose and use a phenological process-based model to assess the impacts of climate change upon the phenology, the suitability and the distribution of economically important cultivars of peach (Prunus persica), across the entire continental France. The model combines temperature dependent sub-models of dormancy, blooming, fruit survival and ripening, using chilling units, forcing units, frost occurrence and growing degree days, respectively. We find that climate change will have divergent impacts upon peach production. On the one hand, blooming will occur earlier, warmer temperatures will decrease spring frost occurrence and fruit ripening will be easily achieved before the start of fall. On the other hand, milder winters will impede the plant buds from breaking endodormancy, with consequent abnormal patterns of fruit development or even blooming failure. This latter impact will dramatically shift the geographic range of sites where peach production will be profitable. This shift will mainly be from the south of France (Languedoc-Roussillon, Rhône-Alpes and Provence-Alpes-Côte d’Azur), to northwestern areas where the winter chilling requirement will still be fulfilled. Our study provides novel insights for understanding and forecasting climate change impacts on peach phenology and it is the first framework that maps the ecological thermal niche of peach at national level.

MODELS TO ESTIMATE CHILLING ACCUMULATION UNDER SUBTROPICAL CLIMATIC CONDITIONS IN BRAZIL

Chilling requirement is a characteristic that limits temperate fruit crops cultivation under subtropical climate. Several mathematic models, differing on the relative value of chilling units have been developed, in order to estimate the chilling accumulation on a given site. The present work compared eight of these models using data from hourly temperatures from May to August, from a period of 11 years, collected in Pelotas, RS, Brazil, aiming to characterize the region regarding the chilling accumulation for the cultivation of deciduous fruit trees and it also had as objective to check if a model using average temperatures is suitable enough to be used when hourly temperatures were not available. The eight tested models were: Chilling Hours (≤7.2°C); Chilling Hours (≤11°C); Utah; Low Chill; Dynamic; Mean Temperatures; Positive Utah and Taiwan. The results showed large differences between years, regardless of the used model. However, the Taiwan and Low Chill models seemed more suitable for the estimation of the accumulation of cold in the Pelotas region. The Medium Temperatures model can be used as a valid option since it has a high correlation with the other models and easy data availability.

Chilling units and chilling hours for southern region of Brazil and Aomori in Japan

The brazilian apple production are located in the southern region, with the best areas in altitudes ranging from 800 to 1400 m, with great variability in the number of Chilling Hours (CH) and Chilling Units (CU) in the different regions and years. The objective of this study was to compare CH equal or below 7.2°C and CU by the North Carolina Modified model in different regions of southern Brazil, comparing with Aomori region in Japan. In Brazil was used historical data of the CH and CU from 2000 to 2016 in the municipalities of Caçador (960 m), Videira (774 m), São Joaquim (1376 m), Fraiburgo (1038 m) and Vacaria (986 m). In Aomori (2.8 m) the historical data used was from 2000 to 2011. The results shows that in southern Brazil there is a variation in the number of CH between sites and years, being greater in the sites of higher altitude, with an average of 880 CH in São Joaquim and 411 CH in Videira. When compared the brazilian regions with Aomori, the japanese region have a greater CH accumulation. Once CU have the same behavior of CH in respect to altitudes, but shows a larger variability between years in the different regions of southern Brazil, is possible to affirm that the North Carolina Modified method is more accurate to quantify the chilling in regions with large temperature fluctuations in the autumn and winter, while for regions with low thermal amplitude, the model of CH presents a better adherence.

Cost of milk production of beneficiary farmers of organized dairy (cooperative and private) in Lucknow region of Uttar Pradesh

Indian dairy industry emerged as an important sector for income and employment generation, and is contributing as well in the country’s economy besides improving the health standards. The output from dairy sector has increased at more than 4.0 % per annum since 2010-11. The changing economic scenario an entrepreneur has to be very alert and should always keep an eye on the cost and returns of the scarce resources of an entrepreneur in order to keep himself profitable. Dairying in our country dominated by the small holders. Now the producers are scaling up their capacity by incorporating newer technology. One hundred and sixty milk pourer farmers were selected randomly using probability proportional to size (PPS) from the list of producers who were supplying milk to organized dairy (cooperative or private) purely and exclusively from eight village level milk chilling units of Lucknow and Hardoi district purposively selected from Lucknow region. Average variable cost varies from 88.72 small, 88.95 medium, and 92.38 large farmers and rest 11.28, 11.05 and 7.62 were the fixed cost for small medium and large category farmers respectively. The cost of milk production was higher for Rs 18.02, Rs 16.30 and Rs 15.85 per liter for small medium and large farmers respectively. The average milk selling price was found to be almost at par for small Rs 27.77, Rs. 27.31 and Rs. 27.11 for small, medium and large category farmers. Whereas, the average income generated by investing one rupee was found lowest for small Rs. 1.56 followed by medium Rs.1.71 and large Rs. 1.75 farmers respectively. However, the farmers have generated average annual income of Rs 70334.21, Rs. 128671.1 and Rs.230510.8 by small medium and large category farmers respectively.

Chilling requirement for seed germination and phenological observations on peach cultivars

In subtropical climate areas, the models and methods proposed to evaluate the chilling requirement of temperate fruit crops often do not provide satisfactory results, thus calling for the development of alternative techniques. The aim of this study was to evaluate the correlations between some phonological traits and chilling requirement for seed germination of 18 peach cultivars and one nectarine cultivar. Two experiments were installed separately for the correlation studies. In experiment 1, the phenological traits were observed in the field, while in experiment 2, the chilling requirement for 50 and 100% seed germination of each cultivar was assessed. The number of days for beginning of bloom (r = 0.70**, 0.61**) and full bloom (r = 0.72**, 0.76**) were both significantly correlated with the number of chilling units for 50% and 100% germination of seeds. The number of days for beginning of budding and dormancy break were both significantly correlated with the number of chilling units for 50% and 100% germination (r = 0.48*, 0.50*, respectively). However, the same significant effect for these phenological traits was not found between chilling units and 50% germination of seeds, as well as between chilling units and harvest dates.