Interactive effects of soil temperature and moisture on Concord grape root respiration

Root respiration has important implications for understanding plant growth as well as terrestrial carbon flux with a changing climate. Although soil temperature and soil moisture often interact, rarely have these interactions on root respiration been studied. This report is on the individual and combined effects of soil moisture and temperature on respiratory responses of single branch roots of 1-year-old Concord grape (Vitis labruscana Bailey) vines grown in a greenhouse. Under moist soil conditions, root respiration increased exponentially to short-term (1 h) increases in temperature between 10 °C and 33 °C. Negligible increases in root respiration occurred between 33 °C and 38 °C. By contrast to a slowly decreasing Q10 from short-term temperature increases, when roots were exposed to constant temperatures for 3 d, the respiratory Q10 between 10 °C and 30 °C diminished steeply with an increase in temperature. Above 30 °C, respiration declined with an increase in temperature. Membrane leakage was 89-98% higher and nitrogen concentration was about 18% lower for roots exposed to 35 °C for 3 d than for those exposed to 25 °C and 15 °C. There was a strong interaction of respiration with a combination of elevated temperature and soil drying. At low soil temperatures (10 °C), respiration was little influenced by soil drying, while at moderate to high temperatures (20 °C and 30 °C), respiration exhibited rapid declines with decreases in soil moisture. Roots exposed to drying soil also exhibited increased membrane leakage and reduced N. These findings of acclimation of root respiration are important to modelling respiration under different moisture and temperature regime

Scion–rootstock interactions influence the growth and behaviour of the grapevine root system in a heavy clay soil

Background and Aims Generally, grapevine roots have been less studied than the above‐ground parts of the plant. Here we analyse scion–rootstock interactions in mature vines growing in a heavy clay soil in a climate characterised by severe summer drought to investigate the effect of the scion–rootstock interaction in a suboptimal soil. Methods and Results The rootstocks, 34 Ecole de Montpellier, 140 Ruggeri and 1103 Paulsen, were grafted onto Nerello Mascalese and Nero d'Avola scions and assessed along with self‐rooted vines. Root distribution and root architecture were analysed using the profile wall method at 0, 60 and 120 cm from the row midline. Root density was greatest at a depth between 21 and 60 cm. The cumulative root fraction for root density registered a β value, a numerical quantity that summarises depth distribution, ranging between 0.932 and 0.962. Root number and density were significantly lower for the self‐rooted vines compared to that of the grafted vines. Conclusions The scion genotypes affected most developmental parameters, including the diameter of the root system, the root density at 21–80 cm depth and the ratio of fine roots to coarse roots. Significance of the Study The scion plays an important role in grapevine root growth, development and distribution in a heavy clay soil, although the mechanism remains unclear

Natural fruitlet abscission as related to apple tree carbon balance estimated with the MaluSim model

Apple trees produce many more flower clusters than needed for a full crop, but natural early season flower and fruitlet abscission drastically reduce the final fruit number. Natural fruit abscission varies significantly year to year. There have been attempts to try to model apple fruit abscission in the past. However, due to the great complexity of a perennial crop system in a dynamic environment with significant plant manipulations, regulatory processes and controlling environmental variables have been difficult to elucidate. In 1995, a field trial was planted at the New York State Agricultural Experiment Station in Geneva, New York with 3 apple cultivars (‘Delicious’, ‘Gala’, and ‘McIntosh’). Beginning in 2000 and for 18 years thereafter, we recorded the natural whole-season fruit abscission of untreated trees that received no chemical or hand thinning. We also estimated early season patterns of carbohydrate supply-to-demand each year with a carbon balance model. These data were used to correlate tree carbon balance status and other environmental variables with natural fruit abscission responses. In general terms, natural set, defined as final fruit/flower cluster, of ‘Gala’ averaged ˜1 fruit for each flower cluster (fruit set = 0.9), whereas fewer fruits were set on ‘Delicious’ and ‘McIntosh’ (fruit set = 0.7 and 0.6, respectively). Fruit set of ‘Gala’ was less variable than of ‘Delicious’ or ‘McIntosh’, and there was a clear pattern for decreasing fruit set when the number of initial flower clusters per tree increased. Fruit weight was less dependent on fruit number for ‘Delicious’ and ‘McIntosh’ than for ‘Gala’. Multiple regression models indicated that number of flower clusters per tree and average carbohydrate balance between 0–60 degree days (DD) after bloom and 300–360 DD after bloom were the main significant variables that explained 60–80% of the variability in natural fruit set or final fruit number. For ‘Delicious’, temperatures of the previous fall also explained a significant amount of variation in final fruit set and final fruit number. For ‘Gala’, carbon balance from bloom to shortly after petal fall and when fruits were about 18 mm were the two main periods, which were more sensible to carbohydrate deficiency triggering fruit abscission. A later susceptible period was also observed for ‘McIntosh’, suggesting a larger thinning window for this cultivar.info:eu-repo/semantics/acceptedVersio

Modelling physiological and environmental factors regulating relative fruit set and final fruit numbers in apple trees

Chemical thinning of apple (Malus domestica Borkh.) has been practised for 50 years but it remains an unpredictable part of apple production with large variations from year to year and within years. Carbohydrate availability to support young fruitlet growth may play a significant role in apple tree response to chemical thinners, especially when the carbohydrate supply is the limiting factor for fruit growth. To address the carbohydrate component, we have tested the MaluSim model that integrates many environmental and tree physiological factors as a tool to predict chemical thinner response. The model suggests that carbon supply-to-demand variations may explain some of the great variations in thinning spray response. Relative fruit set and final fruit number per tree were affected by the carbohydrate balance within 2 days before the spray and up to 5 days after. There was a period, 15–29 days after bloom that thinners showed higher action. The greater the carbohydrate supply relative to demand, the greater the relative set and the final fruit number. This suggested that carbohydrate supply-demand balance may be a baseline for thinner responses, and that integrative modelling of these balances can be useful in understanding variation in thinning responses. Apple relative fruit set and final fruit number per tree could be modelled relatively well with consideration of initial flower density, the carbohydrate balance model, and cumulative growing degree-days since bloom.info:eu-repo/semantics/acceptedVersio

Economics of Drip Irrigation for Juice Grape Vineyards in New York State

R.B. 99-01Grape growers need investment and cost guidelines for drip irrigation to evaluate the economics of getting vines into production as quickly as possible and to avoid periods of drought during the productive life of the vineyard. The benefits of irrigation may include: better vine survival, earlier fruit production, greater yields, more efficient distribution of nutrients, less plant stress, reduced yield variability and improved fruit quality. Research was undertaken to determine drip irrigation investment and annual costs. This project was designed to assist growers in determining the investment, fixed and variable annual costs and expected returns from drip irrigation. Irrigation suppliers provided typical equipment needs and investment costs for various drip irrigation designs. Economic worksheets are provided to assist growers in estimating fixed and variable costs of drip irrigation. The economics of yield data were applied to replicated multiyear irrigation studies to assist growers in determining yield response from drip irrigation. Net present value (NPV) methodology was used to determine the discounted break-even investment results from published responses to drip irrigation. Growers with typical drip irrigation systems and various water sources can expect investments in drip irrigation of $550 to$1,150 per acre with 10 acre blocks of vines. Based upon eight years of data from trials in Fredonia, NY, in the Lake Erie grape belt, average yield increases due to irrigation on establishment and growing of Niagara grapes were 2.8 ton per production year per acre, resulting in a break-even investment of approximately $1,600 per acre. But on established minimal pruned Concord grapes, seven years of data showed a 1.1 ton increase due to irrigation and a break-even investment of only$200 per acre which was well below the total cost of a complete microirrigation drip system. On a new planting of Concords, with droughty soils, the analysis may very well show cost effectiveness. Growers who were interviewed were unable to quantify the benefits and costs of drip irrigation but were pleased with their irrigated yields and brix responses from drip irrigation. This analysis has provided the economic rationale for the investment in microirrigation with some varieties and under certain soil types

Effects of post-bloom low light and girdling on fruit set of Vitis vinifera (L.) cv. ‘Riesling’ and Vitis labruscana (L.) cv. ‘Concord’

Aim: In grapevines, similarly to many woody crops, berry set is a crucial determinant for vine productivity. We reduced vine carbohydrate supply through shading and preventing phloem flow by girdling to investigate the effects on fruit set and berry weight, in field-grown ‘Concord’ (Vitis labruscana L.) and ‘Riesling’ (Vitis vinifera L.) grapevines. Methods and results: Carbon supply to the fruit was manipulated by shading (30% light transmissivity) individual shoots or shading and girdling. Girdling isolated the shoot and its fruit from possible carbohydrate supply from the rest of the vine. Shading was accomplished by covering shoots with a woven strip of shade cloth for four consecutive days in the period between flowering and 28 (‘Concord’) or 16 (‘Riesling’) days after flowering. The percentage of fruit set was calculated from estimated flower numbers using a photographic method and actual berry counts. Conclusions: In both ‘Concord’ and ‘Riesling’, short-time shading caused reductions in fruit set, although this effect was more severe in ‘Concord’. Both species were most sensitive to reductions in carbon supply during the period between 5 and 12 days after flowering. In ‘Concord’ vines, the effects caused by shading were greater with girdling probably because ‘Concord’ vines had higher crop level.  Significance and impact of the study: The results can be used as basis for modelling fruit set in grapevines

Using C. elegans to discover therapeutic compounds for ageing-associated neurodegenerative diseases

Age-associated neurodegenerative disorders such as Alzheimer’s disease are a major public health challenge, due to the demographic increase in the proportion of older individuals in society. However, the relatively few currently approved drugs for these conditions provide only symptomatic relief. A major goal of neurodegeneration research is therefore to identify potential new therapeutic compounds that can slow or even reverse disease progression, either by impacting directly on the neurodegenerative process or by activating endogenous physiological neuroprotective mechanisms that decline with ageing. This requires model systems that can recapitulate key features of human neurodegenerative diseases that are also amenable to compound screening approaches. Mammalian models are very powerful, but are prohibitively expensive for high-throughput drug screens. Given the highly conserved neurological pathways between mammals and invertebrates, Caenorhabditis elegans has emerged as a powerful tool for neuroprotective compound screening. Here we describe how C. elegans has been used to model various human ageing-associated neurodegenerative diseases and provide an extensive list of compounds that have therapeutic activity in these worm models and so may have translational potential

Basics of Water Balance in New York Vineyards

In the humid climate of New York and the Northeast, rainfall is erratic and therefore drought stresses are not easy to predict. Do we have significant problems due to drought (significant enough to change cultural practices or invest in irrigation)? We know the answer depends on how dry the seasons are, how much water our vineyard soil holds, how much the vines need. Since we cannot predict the weather, we must take a risk assessment approach, and then evaluate methods to reduce risks we find. To do that we need to understand the factors that either increase or reduce our risks of significant loss from drought stress