Sentinel-2 Imagery Monitoring Vine Growth Related to Topography in a Protected Designation of Origin Region

Remote sensing satellite platforms provide accurate temporal and spatial information useful in viticulture with an increasing interest in their use. This study aims to identify the possibilities of freely available and with frequent revisit time Sentinel-2 satellites, to monitor vine growth at regional scale on a vine-growing Protected Designation of Origin (PDO) zone during the growing season of the year 2019. This study aims to: (i) investigate through several Vegetation Indices (VIs) the vine growth differences across the zone and relations with topographic parameters; (ii) identify VIs that best recognize differences on subzones of different climatic conditions; (iii) explore the effectiveness of the Sentinel-2 data monitoring management applications. A total of 27 vineyards were selected for field and satellite data collection. Several VIs have been calculated per vineyard from a 20-date time series dataset. VIs showed high negative correlation with topographic parameter of elevation on the flowering stage. The analysis of variance between the VIs of the subzones showed that these regions have statistically significant differences, that most VIs can expose on the flowering and harvest stage, and only Normalized Difference Vegetation Index (NDVI) and VIs using Red-Edge bands during the veraison period. Sentinel-2 data show great effectiveness on monitoring management applications (tillage and trimming).

Leaf-tissue Nutrient Dynamics in Mature Muscadine Cultivars Carlos and Noble in Georgia and North Carolina

More than 3000 acres of commercial muscadine (Vitis rotundifolia) vineyards exist in the southeastern United States. The muscadine wine industry is generating an economic impact of $1 billion in North Carolina alone. Muscadines have been cultivated since the 1800s, but muscadine vineyard fertilizer programs, tissue sampling, and nutrient sufficiency ranges continue to be based on anecdotal knowledge. While seasonal changes in tissue nutrient concentration are well documented in bunch grape (Vitis vinifera), questions remain about the seasonal and cultivar-dependent dynamics of muscadine leaf tissue nutrient concentrations. The aim of this study was to assess temporal and cultivar-related differences in tissue nutrient concentration of mature commercially grown muscadines. Leaf tissue nutrient concentration of the muscadine cultivars Carlos and Noble were assessed in three vineyards (Piedmont North Carolina, north Georgia, and south Georgia) at bloom, véraison, and postharvest in 2018 and 2019. Our results show that nitrogen (N), phosphorus (P), and manganese (Mn) were generally above the recommended sufficiency ranges, with calcium increasing over the season—and N, P, and potassium decreasing over the season. ‘Carlos’ had significantly higher levels of N and P, compared with ‘Noble’, while ‘Noble’ showed higher Mn concentration than ‘Carlos’. With this evaluation, we demonstrate the need for a modification in muscadine tissue nutrient sufficiency ranges that are based on cultivar and vine growth stage.

Yield and Economic Response of Peanut (Arachis hypogaea L.) Cultivars to Prohexadione Calcium in Large-Plot Trials in Georgia

Prohexadione calcium, a plant growth regulator, has been used on virginia market type peanut cultivars for many years to manage excessive vine growth and improve digging efficiency. Prohexadione calcium has not been widely used on runner market type cultivars due to their slower growth habit and sporadic yield response at the labeled rate until recent research showed lower use rates of prohexadione calcium provided similar vine control and enhanced yield response. Large plot experiments were conducted in Colquitt county at the Darrell Williams Research Farm on the Sun Belt Ag Expo to quantify yield and market grade quality and economics of using prohexadione calcium at 105 g a.i./ha on six runner type cultivars. Prohexadione calcium was applied twice during the growing season. The first application was made when 50% or greater of lateral vines from adjacent rows were touching. A second application of each treatment was applied 14d after the first application. The runner type cultivars were Georgia-06G, Georgia-12Y, Georgia-13M, Georgia-14N, TUFRunner TM -297, and TUFRunner TM -511. Similar large-plot experiments were conducted on farms in Baker and Early counties evaluating yield and economic response of prohexadione calcium on Georgia-06G. A non-treated control was used in all experiments. Prohexadione calcium increased pod yield in all experiments ranging from 450 to 650 kg/ha compared to the non-treated control with response similar across cultivars. Prohexadione calcium reduced the dollar value per metric ton (DVMT) as a result of lowering total sound mature kernel (%TSMK) percentages up to 3 points. The higher yields obtained for the prohexadione calcium-treated peanut provided higher gross dollar value return/ha (GDR) in all experiments and higher gross dollar value return/ha above treatment cost (GDRAT) in the on-farm trials. Therefore, prohexadione calcium at 105 g/ha applied twice on runner market type peanut is warranted to improve yield and financial return when excessive vine growth is a concern.

Compatibility and initial development of grapevines ‘BRS Magna’ grafted on different rootstocks

ABSTRACT: Rootstocks are widely used in viticulture due to their resistance to biotic and abiotic stress. Additionally, rootstocks can affect vine growth and fruit quality. This study evaluated the compatibility and initial developmental of the ‘BRS Magna’ grafted on different rootstocks The wedge graft technique on woody cuttings was utilized. The percentage of survival ranged from 0% (‘VR043-43’) to 98.33% (‘101-14 MGT’), and the rootstock were grouped into three distinct groups. ‘IAC 313 Tropical’ and ‘SO4’ rootstocks were those ones with the highest vigor in relation to initial shoot growth. However, ‘IAC 572 Jales’, ‘Harmony’, ‘3309 Couderc’ and ‘Gravesac’ had the best balance between initial shoot growth and root development. The ‘BRS Magna’ when grafted on rootstocks ‘IAC 313 Tropical’, ‘SO4’ and ‘101-14 MGT’ showed the highest initial development rates, while when grafted on ‘R99’, ‘R110’ and ‘420A’, it showed the lowest initial development.

Influence of Prohexadione Calcium Rate on Growth and Yield of Peanut (Arachis hypogaea)

ABSTRACT Prohexadione calcium, a plant growth regulator, is commonly used on virginia market type peanut (Arachis hypogaea L.) cultivars to manage excessive vine growth and improve digging efficiency. However, use of prohexadione calcium on runner market type cultivars has been minimal. The objective of this research was to evaluate prohexadione calcium on virginia and runner market type peanut cultivars at multiple rates in small-plot (17 site years) and on-farm (5 site years) experiments. Applications of prohexadione calcium were at the manufacturer's recommended use rate of 140 g a.i./ha (1x), 105 g a.i /ha (0.75x), and 70 g a.i /ha (0.5x) rates. A non-treated control was also included in all experiments. Cultivar and treatment responses were evaluated based on mainstem height, yield, total sound mature kernels, and return on investment. Plants treated with prohexadione calcium had greater row definition based on a 1-10 row visibility rating scale. Plant main stem heights were often shortened when prohexadione calcium was applied compared to the control, although response varied by location and by year. Average mainstem heights were 26 cm for non-treated plots and 23 cm for prohexadione calcium treated plots across all virginia market type small plot experiments. Prohexadione calcium did not significantly increase yield at any rate in any small plot experiments regardless of rate. Reduced rates of prohexadione calcium significantly increased yield in all the large on-farm experiments compared to the control. Yield increases ranged from 453 to 731 kg/ha for all prohexadione calcium treatments compared to the control across all large plot on-farm experiments. The greatest return on investment was the 0.75x rate resulting in an increase in revenue of $210 ha−1. With an increase in yield and return on investment in all large plot on-farm experiments and not in small plot experiments no matter the market type, it is assumed that the growth and yield response to prohexadione calcium may be more pronounced where soil variability is greater, affecting growth, digging, and yield potential. Prohexadione calcium can be beneficial in virginia market type and runner market type peanut cultivars to decrease vine growth and increase yield.

Parasitoid Abundance and Community Composition in Desert Vineyards and Their Adjacent Natural Habitats

Parasitoids are important natural enemies of many agricultural pests. Preserving natural habitats around agricultural fields may support parasitoid populations. However, the success of such an approach depends on the ability of parasitoids to utilize both crop and natural habitats. While these aspects have been studied extensively in temperate regions, very little is known about parasitoid communities in desert agroecosystems. We took one step in this direction by sampling parasitoids in six vineyards and their surrounding natural desert habitat in a hyper-arid region of the Negev Desert Highlands, Israel. We predicted that due to the high contrast in environmental conditions, parasitoid abundance and community composition would differ greatly between the crop and the natural desert habitats. We found that parasitoid abundance differed between the habitats; however, the exact distribution pattern depended on the time of year—with higher numbers of parasitoids in the natural habitat at the beginning of the vine growth season and higher numbers in the vineyard at the middle and end of the season. Although parasitoid community composition significantly differed between the vineyard and desert habitats, this only accounted for ~4% of the total variation. Overall, our results do not strongly support the notion of distinct parasitoid communities in the crop vs. the desert environment, suggesting that despite environmental contrasts, parasitoids may move between and utilize resources in both habitats.

Mechanical Pruning and Soil Fertilization with Distinct Organic Amendments in Vineyards of Syrah: Effects on Vegetative and Reproductive Growth

The effects of fully mechanized pruning systems on physiology, vigor and yield of grapevines have been studied for more than forty years and are an interesting way to reduce production costs. Organic amending of vineyard soil is a way to increase vine productivity. Thus, this study aims to understand the effects of the interaction between these two practices, on vine growth and productivity. Two trial fields were implemented on Shiraz vineyards in 2 different wine regions. Mechanical hedge pruning was compared with hand spur pruning and four different organic amendments were tested: biochar; municipal solid waste compost; cattle manure; sewage sludge. Mechanical pruning and organic amendments, by themselves, did not significantly increase yield. However, the interaction between both factors reduced the impact of self-regulation mechanisms (budburst, bud fruitfulness and cluster weight) in mechanical pruning and successfully increased yield, without decreasing vegetative growth. The effects of mechanical pruning with the application of organic amendments to soil on yield is significant and, thereby, the choice of the organic amendment and its amount, must be done considering the destiny of produced grapes.

Rootstock Evaluation for Grafted Cucumbers Grown in High Tunnels: Yield and Plant Growth

Grafting technology is increasingly being accepted in the United States, particularly for tomato (Solanum lycopersicum) production under protected structures. There is a great potential to expand this technology to other high tunnel crops. Using grafting technology in cucumber (Cucumis sativus) production is widely adopted in Asia to enhance cucumbers’ tolerance to low temperatures. But this technique is rarely used in the United States mainly because of the lack of information on the performance of the grafted plants under local production systems. Figleaf gourd (Cucurbita ficifolia), Cucurbita moschata, and squash interspecific hybrid (Cucurbita maxima × C. moschata) are the most used cucumber rootstocks worldwide. But their comparative performance was largely unknown for cucumber production in high tunnels in the Midwest United States. This study was therefore designed to compare the major types of cucumber rootstocks with the goal of identifying a rootstock with the maximized benefits for high tunnel cucumber production in the area. Nongrafted ‘Socrates’ and ‘Socrates’ grafted with Cucurbita moschata, squash interspecific hybrid, and figleaf gourd rootstocks were evaluated in high tunnels from March to June or July in 2016–19 at the Southwest Purdue Agricultural Center in Vincennes, IN. Transplant establishment, vine growth, and yield in early- and main-crop seasons were investigated. Grafted plants regardless of rootstocks ensured transplant survival even when the soil temperatures were dropped below 10 °C. Suboptimal soil conditions were encountered in the first month after transplanting. Grafted cucumbers with squash interspecific hybrid rootstock significantly increased vine growth from March to April and increased early-season yields (yield before 15 May) by 1.8 to 18.2 times compared with the early-season yields of the nongrafted cucumbers. The benefits provided by using grafting technology dismissed around middle May. Only squash interspecific hybrid rootstock improved cucumber yields in the entire production seasons. Cucumbers grafted with figleaf gourd rootstock had the lowest yield and the least plant growth after mid-May, indicating figleaf gourd rootstock may not be suitable for cucumber production under the current production system. Overall, squash interspecific hybrid was the most promising rootstock for early-season high tunnel cucumber production in the Midwest United States.