June Planting Research Articles

Assessing the influence of planting time and fertilization on growth, flowering, yield and soil properties of chrysanthemum

ObjectivesTo identify optimal planting time for maximizing growth and flowering, and assess the impacts of various fertilization techniques on plant growth and soil health in chrysanthemum. MethodsThe investigation was conducted at Dr. Y.S. Parmar University of Horticulture and Forestry in Nauni, Solan, Himachal Pradesh, India from 2022 to 2023. The study aimed to investigate the impact of various planting times and fertilization schedules on the yield, quality, and soil health characteristics of chrysanthemum. Different planting times from 15 June to 30 August under organic and inorganic fertilization regimes were evaluated. Data related to vegetative growth, flowering, soil chemical and biological properties were recorded. ResultsPlantingon15 June along with inorganic fertilization resulted in improved vegetative characters like plant height (74.37 cm) and plant spread (30.56 cm), flowering characters like cut flower stem length (64.07 cm), stem strength (10.40°), flower diameter (11.80 cm) and duration of flowering (22.50 days) and soil chemical properties like available N, P, K (326.53, 40.36 and 359.48 kg/ha, respectively). However, planting on June 15 combined with organic fertilization led to enhancement in soil microbiological properties, including bacterial count (138.33 cfu/g soil), fungal count (31.75 cfu/g soil), actinomycetes count (62.46 cfu/g soil), microbial biomass (52.62 µg/g soil) as well as vase life (19.70 days). ConclusionIn the present study, it was found that planting time and fertilization significantly impacted chrysanthemum growth, yield and soil properties. The 15 June planting with inorganic fertilization boosted growth, yield and macronutrient content, while organic fertilization on the same date enhanced soil microflora. Flowering was influenced by planting time and organic fertilization showed promise as an alternative to chemical fertilization. Optimizing planting schedules and using organic fertilizers would lead to sustainability and offer economically viable alternatives to conventional crop management.

Analysis of Potential Cropping Seasons of Cayenne Pepper (Capsicum frustescens L.) Based on Water Balance in Alfisol Dryland, Tuban Regency, East Java, Indonesia

Dryland agriculture is crucial for understanding how to effectively manage land water for the crops. Water balance analysis plays a pivotal role in comprehending the hydrological cycle and water availability for crop production. The Tuban Regency is one of the fifth largest cayenne pepper-producing areas in East Java, Indonesia, particularly in Grabagan and Bancar Districts. However, for sustainable growth, it is imperative to extend cultivation to other sub-districts within Tuban Regency. In the cultivation of cayenne pepper, attention to soil water availability is important due to its susceptibility to drought, directly impacting vegetative growth and overall plant production. This research aims to establish a planting pattern for cayenne pepper based on water balance analysis in Alfisol drylands within Montong, Kerek, and Singgahan Districts of Tuban Regency. The study, conducted from July to September 2023, employed Thornthwaite and Mather water balance analysis,drought index assessment, and day without rain analysis. The research findings reveal variations inwater balance conditions within the study areas, with Montong and Kerek Districts experiencing a land water surplus for three months and a nine-month deficit. Singgahan District, on the other hand, encountered a surplus for four months and a deficit for eight months. The drought index indicates a high level, peaking in September for Montong (87%), Kerek (91%), and Singgahan (87%) Districts. Cayenne pepper plants exhibit the potential for annual cultivation in Alfisol drylands of Montong, Kerek, and Singgahan Districts, with a growing duration of six months. The optimal planting window spans from December to May, followed by potentially a second planting in June and July for crops with a minimum available water value exceeding 19% or those with a shorter harvest life. From August to November, the land lies fallow due to a soil water availability that is close to 0% and a 27% risk of days without rain in the extreme drought category, rendering the soil unsuitable for growing crops.

Soybean planting date and seeding rate effect on germinability and vigor of harvested seed

AbstractSeed is one of the most crucial inputs for soybean [Glycine max (L.) Merr.] production due to its influence on plant population, uniformity, and yield, as well as its cost as an input. Seeds of good quality have high germinability and vigor, providing an adequate stand with uniformly good growth and development even under adverse conditions. This study aimed to measure the effect of soybean planting date and seeding rate on harvested seed mass, seed germinability, and seed vigor. Seeds were collected from a field experiment during the 2020 and 2021 growing seasons at two locations in Ohio: Western Agricultural Research Station and Northwest Agricultural Research Station. The study was conducted using a split‐plot randomized complete block design (planting date–whole plot; seeding rate–subplot) with four replications. Standard germination and accelerated aging tests were conducted in the laboratory using seeds harvested from the field study. All four site‐years demonstrated that planting soybean very late (June 16–July 1) produced lower weight seeds than the other planting dates. Across planting date and seeding rate treatments, the harvested seed germinability was ≥94%. However, soybean planted in early June (June 1–June 15) had the lowest seed vigor results (64%–81%) compared to other planting dates (80%–89%). Rainfall at R7–R8 development stages is negatively correlated with the seed vigor. The results will help seed producers optimize seed production and quality and suggest avoiding planting in June to increase harvested seed vigor.

Impact of Planting Date on Growing Degree Units, Grain Yield and Growth Traits of Some Egyptian Yellow Maize Inbred Lines

This study was conducted in 2021 to study the impact of planting date on maize inbred lines and determine their accumulated growing degree units (GDU).The experiment was held at three agriculture research stations (Gemmeiza, Ismaelia and Sids) with RCBD of four replications. It was planned to provide also some insights to optimize maize production and mitigate the impact of climatic changes to all researchers in the scientific community. Three planting dates i.e. April 20th (early), May20th (optimal) and June 20th (moderately late) were applied to investigate their effect on number of days to 50% tasselling and silking, plant height and grain yield of 16 Egyptian yellow maize inbred lines. In addition, to determine accumulated growing degree units (GDU) from planting to 50% silking. Results revealed highly significant differences among tested inbreds for all studied traits at the three planting dates indicating presence of genetic diversity among tested inbreds. Also, the same trend was found for differences among locations and inbreds x location indicating climatic variability among the three testing locations and that inbreds behaved differently at different locations due to differences in climatic conditions among locations and also genetic diversity among inbreds. Number of days to 50% tasselling and silking was reduced from April to June planting as a result of increased temperatures during plant development. Longest plant heights were obtained in April planting as a result of prolonged vegetative growth due to cool - moderate temperatures prevailing at early vegetative growth. Grain yield of all tested inbreds was reduced, with few exceptions, in June 20th planting as a result of high temperatures prevailing at time of tasselling and silking which resulted in pollen, stigma or fertilization abortion and caused poor seed setting. Highest yield of studied inbreds was obtained at Gemmeize location in April 20th planting and it is recommended as a suitable production location for inbreds. Inbred Sakha 3 was the best performing under variable planting dates. Also, inbreds Sakha 1, Sakha 11, Gz 639 and Gm 1021 performed well on certain planting dates. Determination of accumulated growing degree units for tested inbreds revealed big variation among them as a result of genetic diversity of inbreds and matched well with variation present in their silking dates and specified earliness or lateness of tested inbreds. Results of GDU would help in expectation of timing for many agricultural practices such beginning of detasselling process and harvest time in hybrid breeding programs.

Soybean planting date and seeding rate effect on grain yield and profitability

AbstractTimely soybean [Glycine max (L.) Merr.] planting is ideal for maximizing grain yield. However, weather conditions often limit farmers’ ability to plant timely. The objectives of this study were to (a) measure the effect of soybean planting date and seeding rate on grain yield, (b) identify the agronomic optimum seeding rate (AOSR; the seeding rate where soybean yield is maximized), and (c) compare the net economic return of the base treatment (May 10 to 31 planting date and 370,000 seeds ha−1 seeding rate) to the other treatment combinations. The experiment was conducted in 2020 and 2021 in Ohio at the Western (WARS) and Northwest (NWARS) Agricultural Research Stations with a split‐plot randomized complete block design with four replications. The whole plot factor was four planting dates ranging from April 25 through July 1, and the sub‐plot factor was five seeding rates ranging from 123,500 to 618,000 seeds ha−1. When water was not limiting, soybean planted in April and May yielded 8% to 26% more than soybean planted late June. In general, planting in May resulted in a lower AOSR (247,000 to 303,000 seeds ha−1), compared to planting in June, where AOSR ranged from 430,000 to 618,000 seeds ha−1. Comparative net economic return was the lowest (from $237 ha−1 to $938 ha−1) when soybean was planted after mid‐June at 123,500 seeds ha−1. These findings can help farmers improve soybean grain yield by adjusting their seeding rate based on planting date to maximize profitability.

Exploring adaptation responses of maize to climate change scenarios in southern central Rift Valley of Ethiopia

In this study, we assessed responses of adaptation options to possible climate change scenarios on maize growth and yield by using projections of 20 coupled ensemble climate models under two representative concentration pathways (RCPs) 4.5 and 8.5 by means of a DSSAT model. Growth and yield simulations were made across present and future climate conditions using the hybrid maize variety (Shone). Subsequently, simulated yields were compared with farmer’ average and on-farm trial yields. Results showed that on-farm trial yield (5.1–7.3 t ha−1) lay in between farmers’ average yield (2.9–5 t ha−1) and water-limited potential yield (6.3–10.6 t ha−1). Maize yields achieved in farmers’ fields are projected to decline towards mid-century and further towards the end of the century regardless of the adaptation options compared with baseline in low potential clusters. Results of a combination of adaptation options including February planting, use of 64 kg ha−1 N and conservation tillage provided yield advantage of 5.8% over the 30 cm till under medium GHGs emission scenario during mid-century period at Shamana. Mulching with 5 t ha−1 was projected to produce a 4–5% yield advantage in the Hawassa cluster during the mid-century period regardless of changes in tillage or planting window. Under a high GHGs emission scenario, over 13.4% yield advantage was projected in the Bilate cluster due to conservation tillage and June planting during the mid-century period. In the Dilla cluster, the use of 10 t ha−1 mulch, conservation tillage and early planting (February) would result in a 1.8% yield advantage compared with the control either in medium or high GHGs emission scenarios. Thus, the most promising and least risky practices among simulated strategies were the use of nitrogen and mulching in combination with tillage or planting date adjustment. However, adaptation options remained least promising and highly risky if not integrated with mulching or nitrogen use. Hence, the negative impacts of future climate change and subsequent yield gaps would be reduced by optimizing the application of nitrogen, mulch and their interaction with planting date and tillage in high and low potential areas of maize production.

Improving wheat productivity through integrated management of Avena ludoviciana

AbstractIn Australia, wheat planting is preferred in June compared with May to kill early cohorts of weeds before planting, particularly in fields with a history of high weed infestation. However, wheat grain yield is often reduced for June planting. This study aimed to investigate the integrated effect of planting dates (May 7, i.e., early‐planted, and June 7, i.e., late‐planted), seeding rates (100 and 200 seeds m−2), and weed control treatments (nontreated control, pyroxasulfone 100 g a.i. ha−1, triallate 800 g a.i. ha−1, trifluralin 600 g a.i. ha−1, and prosulfocarb 2000 g a.i. ha−1 + S‐metolachlor 300 g a.i. ha−1) on Avena ludoviciana (Durieu) control and wheat yield. For early‐planted wheat, the pyroxasulfone‐treated plots had a higher yield (5.5 Mg ha−1) at a low seeding rate compared with a high seeding rate (4.7 Mg ha−1). Pyroxasulfone and triallate treatments in early‐planted wheat using a low seeding rate produced a higher yield than each treatment of late‐planted wheat. In late‐planted wheat, varied seeding rates did not influence grain yield, irrespective of weed control treatments. Pyroxasulfone and triallate treatments in early‐planted wheat at a low seeding rate gave similar yields, and yield levels in these treatments were higher than trifluralin and prosulfocarb + S‐metolachlor treatments. A high seeding rate in early‐planted wheat resulted in an increased grain yield by 42%, 27%, and 28% in nontreated, trifluralin, and prosulfocarb + S‐metolachlor, respectively, compared with a low seeding rate. Weed biomass and weed seed production were lower in late‐planted wheat than in early‐planted wheat. Pyroxasulfone‐ and triallate‐treated plots accrued lower weed biomass and weed seed production than the nontreated plots. Averaged over weed control treatments, weed seed production was highest (2700 seeds m−2) in the early crop planted at a low seeding rate, which was reduced by 42% with late planting using a similar seeding rate. Averaged over weed control treatments, a high seeding rate in early‐ and late‐planted crops reduced weed seed production by 68% and 48%, respectively, compared with a low seeding rate. These results suggest that pyroxasulfone in early‐planted wheat can control A. ludoviciana effectively, limit weed seed production similar to late‐planted wheat, and prove a profitable option due to improved productivity compared with late‐planted wheat.

Evaluation of cauliflower genotypes to different planting dates for early production in Kathmandu valley

A field experiment was conducted to evaluate ten cauliflower genotypes at the National Horticulture Research Centre, Khumaltar, Lalitpur from June to December of 2019 and 2020. The experiment was laid out in Randomized Completely Block Design with ten genotypes (Chinese, Sarlahi Deepali, Pusa Katiki, Taichun, Pusa Sarad, Terai 1, Terai 2, Agheni, Cold Queen and Khumal Jyapu) planted on three dates i.e. June 25, July 15, and August 5 at a 20-day interval. The main objective of this study was to identify planting dates for cauliflower genotypes suitable recommended to planting in early-season under Kathmandu valley conditions. The results showed that planting dates significantly influenced the growth and yield of cauliflower genotypes. At 25th June planting, the genotype Sarlahi Deepali had the significantly lowest days to curd maturation (41 days after transplanting), which was at par with Pusa Katki and Terai -2 (46 DAT) with the lowest yield of 4.0 mt ha-1 and 3.2 mt ha-1, respectively. However, curd weight (438.6 g) and yield (27.4 mt ha-1) were recorded as the maximum in Chinese with 51 days maturity period. On the 15th July planting, Terai 2 had the lowest maturity days (44 DAT), but lower yield (14.6 mt ha-1), while Cold Queen had the highest curd weight and yield (560.8 g and 35.1 mt ha-1), which was at par with Chinese (546.7 g and 34.2 mt ha-1). Similarly, on the 5th August planting, the genotype Terai 2 had the significantly (p<0.001) lowest days to maturity (46 DAT), followed by Sarlahi Deepali (57) and Pusa Katiki (57), whereas the genotype Cold Queen had the highest curd weight and yield (842.1 g and 52.6 mt ha-1), followed by Taichun (718.8 g and 44.9 mt ha-1) and Terai 1 (452 g and 28.3 mt ha-1). The results revealed that genotype Sarlahi Deepali was found to be early maturing for June planting, while Terai 2 was found early for July and August planting, but were not found suitable due to lower yield. The genotypes Chinese and Cold Queen were found best for June and July planting, respectively. Similarly, Cold Queen and Taichun were promising genotypes for August planting.

Charcoal Rot Severity and Soybean Yield Responses to Planting Date, Irrigation, and Genotypes

Soybean (Glycine max [L.] Merr.) production is influenced by planting date, but its impact on yield in fields infested with Macrophomina phaseolina (Tassi) Goid. is unknown. A 3-year study was conducted in M. phaseolina-infested fields to assess the effects of planting date (PD) on disease severity and yield using eight genotypes, four of which are reported to be susceptible to charcoal rot (S), and four reported with moderate resistance (MR) to charcoal rot (CR). The genotypes were planted in early April, early May, and early June under irrigated and nonirrigated conditions. There was planting date by irrigation interaction for area under the disease progress curve (AUDPC) where May PD was significantly lower compared to April and June PDs in irrigated environments but not in nonirrigated environments. Correspondingly, yield in April PD was significantly lower than that of May and June. Interestingly, yield of S genotypes increased significantly with each subsequent PD, while yield of MR genotypes remained high across all three PDs. The interaction of genotypes by PD on yield revealed that the MR genotypes DT97-4290 and DS-880 had the greatest yields in May compared to April. While May PD had a decreased AUDPC and an increased yield across genotypes, the result of this research suggests that in fields infested with M. phaseolina, early May to early June planting coupled with appropriate cultivar selection provides maximum yield potential for western Tennessee and mid-southern soybean growers.

Effect of Fertilization and Planting Date on the Production and Shelf Life of Tuberose

The tuberose, Agave amica, is an ornamental plant appreciated for its oils. The objective of this study was to evaluate the effect of planting dates (April, May and June), dose of NPK (N80-P60-K40, N300-P200-K200, N100-P50-K50 and N00-P00-K00), and fertilizer sources (chemical, organic, combined and control) on tuberose production, flower quality and postharvest shelf life. The physiological variables spike characteristics, leaf color, biomass, and postharvest flower quality were evaluated. The results show that the best planting date is in June; plants planted in June flowered earlier (156 days) and had better flower quality. The fertilization formula N300-P200-K200 produced a higher number of spikes (1.32) and flowers (38.93), a larger stem diameter (0.9 cm), and promoted fewer days to flowering (188d). Plants fertilized with chemical fertilizer had fewer yellow leaves, a larger number of spikes (1.41), a longer spike length (26.89 cm), and a higher number of flowers/spikes (39.28), corms/plants (31.03), and open flowers on the ninth day in vase (13.14) and heavier stems with spikes (134.80 g). In conclusion, the dose of N300-P200-K200 from chemical source and planting in June produced the best flower quality and the shortest production cycle.

The Effects of Planting Date and Tillage Practice on Growth and Yield of Maize and Soybean in Rotation with Winter Onion

Introducing summer staple crops to diversify conventional summer paddy rice (Oryza sativa L.) and onion (Allium cepa L.) rotation is important for sustainable agriculture. Herein, we evaluate the effects of planting date (early June to late July) and tillage practice (deep cultivation, DC; conventional tillage, CT) on two maize and soybean cultivars over 4 years (2018–2021) in converted paddy soil in Korea. Due to the growing degree-day differences, the yields of June and July planted crops were 7050 and 5554 total digestible nutrient kg ha−1, respectively, for silage corn, and 7410 and 6473 marketable fresh ear kg ha−1, respectively, for waxy corn. Delaying soybean planting from June to July significantly reduced crops’ yield and interfered with field preparation for the following winter cash crops. The June and July planting yields were 2672 and 2090 kg ha−1, respectively, for large-grain soybean, and 2416 and 1861 kg ha−1, respectively, for small-grain soybean. Deep tillage had no effect on summer crops yield. Additionally, the summer crop growing practice had no residual effect on onion yield. Our study recommends mid to late June planting for growers who wish to introduce maize and soybean in rotation with winter onion in the region.

Aromaticity of secondary products as the marker for sweet sorghum [Sorghum bicolor (L.) Moench] genotype and environment effects

Although data analytics and systems modeling are increasingly being utilized to interpret genotype × environment interactions in plant breeding, chemometrics is currently underutilized. Prior reports indicated correlations between redox-active polyphenols in stem juice of sweet sorghum [ Sorghum bicolor (L.) Moench] and its resistance against sugarcane aphid [ Melanaphis sacchari (Zehntner)]. However, such correlations are often confounded by the outperforming genotype (outlier in correlations) capable of accumulating several-fold higher secondary metabolites than other cultivars examined. To investigate the underlying chemical characteristics responsible for the pest resistance, this study first employed principal component analysis (PCA) as the exploratory analysis to visualize the primary factors affecting genotype and environmental (April, May, and June planting months) dependence of juice extracted from 24 sweet sorghum cultivars. Chemical parameters arising from redox reactivity were primarily responsible for distinguishing a resistant genotype. The distance of dendrogram based on the genotype-dependent electrochemistry (cyclic voltammetry) was then used as the perturbation parameter in 2D correlation analysis to understand the controlling chemical structures; both genotype and environment were controlled by the redox reactivity and aromaticity of sweet sorghum. Aromatic structures detectable by UV/visible spectrophotometry were then used to build calibrations based on machine learning. The workflow of data analytics in this study could be applied to expedite the biomarker-driven plant breeding without repeating chemical analysis of new field samples. • Redox reactivity of sorghum juice can serve as the marker for pest resistance. • 2 D correlation analysis of cyclic voltammogram revealed genotype dependency. • Machine learning allows calibration of redox reactivity without repeated analysis.

Impact of planting dates on yield and pod quality traits of snap bean under short-temperate season climates

Snap bean, a warm-season crop, have low frost tolerance. The optimal temperature for seed emergence and plant growth is important. Therefore, appropriate planting dates for adapted varieties has paramount significance in improving pod yield and quality of snap bean under short cool season climates. Three snap bean cultivars planted at 3 different dates were examined to evaluate the effects of planting dates on snap bean pod yield and quality traits in a 2-year study in a short season climate in Manitoba, Canada. Results of this study showed that three, two weeks apart, planting dates had a non- significant effect on marketing yield of three different cultivars tested in this study. Planting dates showed significant effect on un-marketable yield, pod fresh weight, pod length and total soluble solids. Higher marketable and un-marketable yields along with longer pod length and soluble solids, in all three cultivars, were more profound when seeded at mid and late planting dates. Snap bean grew under higher temperature and accumulated more growing degree days (GDD) when planted in mid June and early July when compared to early June planting. These results conclude that marketable yields of snap bean were not significantly affected by planting dates when seeded-two weeks apart-in shorter growing environments which allow commercial and market gardeners, in northern areas with shorter growing seasons to optimise planting snap bean, without reducing pod yield and quality.

Seed Yield and Economics of Prickly Sesban under SpatioTemporal Variation in Sowing in Coastal Odisha

F ield experiment was conducted at Bhubaneswar, Odisha during 2019 to study the response of prickly sesban to spatio-kharif temporal variation in planting. The treatments of the study comprised five dates of planting. First sowing was done with onset of monsoon on June 13 and rest four at weekly intervals 20 and 27 June, 4 and 11 July with three row spacings . 80, 120 and 160 cm. Planting on 13 June . on viz at row spacing of 80 cm recorded the maximum seed yield of 1.271 t/ha while planting on 13 June at row spacing of 120 cm and planting on 20 June at row spacing of 80 and 120 cm recorded statistically similar seed yields. All other combinations of date of planting and row spacing were inferior to the combination of 13 June planting with row spacing of 80 cm. The earliest date of planting at the closest row spacing recorded the maximum net return of Rs 96.17 x10 /ha and return per rupee investment of Rs 2.27.

Planting date and fertilizer type influenced soil quality indices and soybean (Glycine max L.) yields in derived savannah of Nigeria

Soybean is grown in many parts of Northern Nigeria, with little climatic challenges and soil organic matter. There is need to investigate possible influence of planting date of the crop in Southeastern Nigeria, an environment that is rather foreign to the crop. A study was carried out in 2018 and 2019 cropping seasons at Federal College of Agriculture, Ishiagu, Ebonyi State, to evaluate the influence of different planting dates and fertilizer types on selected soil physical and chemical properties, growth and yield of soybean. A split plot in a randomized complete block design was used with planting date (May and June) as the main plots, while six fertilizer types (poultry-droppings manure 5 t ha–1, swine-droppings manure 5 t ha–1, rice-husk dust 5 t ha–1, NPK 15:15:15 at 150 kg ha–1, urea at 100 kg ha–1 and the control) constituted the sub-plots. At crop maturity, some soil quality indices and pod and grain yields (t ha–1) of soybean were assessed. Soil organic carbon (SOC) and total nitrogen contents were significantly (p < 0.05) influenced by both planting date and fertilizer type in 2018 and 2019, while soil pH was improved significantly (p < 0.05) only by fertilizer type in these two cropping seasons. Mean-weight diameter of aggregates, soil bulk density and SOC stock as well as soybean yields were significantly (p < 0.05) influenced by both planting date and fertilizer type in the two seasons. Generally, planting in May improved soil total nitrogen and soybean pod yield whereas planting in June improved the other soil quality indices and soybean grain yield, the best soil amendment in either case being poultry-droppings manure but sometimes parameter-specific. The choice of planting date (May or June) in soybean production in the derived savannah and the soil amendment to use in the enterprise thus has both agronomic and environmental implications. Such a choice would depend on the indices of soil quality and/or the aspects of soybean yields (pod or grain) whose improvements the farmer intends to achieve at crop maturity.

Juice chemical properties of 24 sorghum cultivars under varying levels of sugarcane aphid (Melanaphis sacchari) infestation

Sugarcane aphids [Melanaphis sacchari (Zehntner)] have become a significant pest of grain, forage, and sweet sorghum [Sorghum bicolor (L.) Moench] in the USA in recent years. However, the effects of sugarcane aphid damage on sweet sorghum juice quality have not been well studied. A three-year (2015–2017) field study was conducted at Tifton, GA to assess planting date effects (April, May, or June planting) and cultivar responses (24 cultivars) to sugarcane aphids in sorghum. Aphid damage ratings were measured in all three years and cumulative aphid days were measured in 2016 and 2017. Cumulative aphid days (ln scale) and damage ratings (relative marginal effect) were correlated in five of the six plantings. Stem juice was collected at maturity from seven plantings for chemical analyses, which included HPLC, fluorescence excitation-emission spectrophotometry with parallel factor analysis (EEM/PARAFAC), and cyclic voltammetry (CV). Aphid damage ratings and cumulative aphid days were negatively correlated with sugar-related traits, particularly brix and total sugars. In four plantings, significant negative correlations (r ≤ −0.493) between trans-aconitic acid concentration and aphid damage were observed. Fluorescence and electrochemical properties related to the presence of polyphenols also showed correlations with aphid damage, particularly in the resistant landrace No. 5 Gambela. These secondary metabolites may play a role in sugarcane aphid resistance or tolerance. Stability analysis revealed that the more tolerant cultivars were able to maintain high concentrations of total sugars and trans-aconitic acid across environments.

Season and date of harvest effects on dry matter yield of sunn hemp (Crotalaria juncea L.) 'Tropic Sun' in northwestern Puerto Rico

An experiment to evaluate the effects of planting season and harvest dates on biomass production and nitrogen accumulation by sunn hemp was conducted at the Agricultural Research Station, Isabela, Puerto Rico. Sunn hemp Tropic Sun' was established in an Oxisol soil (Cotito series) at a seeding density of 10 kg/ha. Dry matter yield (DMY) was estimated at 71,92 and 121 days after planting (DAP) in June and November. Effects of both major variables were significant (P > 0.05) for DMY, the June planting far surpassing that of November (15,831 vs. 5,665 kg/ha); DMY increased progressively for the three harvest dates (7,704; 11,141; and 13,398 kg/ha). Maximun biomass production (20,734 kg/ha) was obtained at 121 DAP in June, thus exceeding by threefold that of November at 121 DAP (6,062 kg/ha). Nitrogen accumulation followed a similar pattern, with that of June surpassing that of November (352 vs. 147 kg/ha) and values ascending for the successive harvest dates (193, 254, and 303 kg/ha). Differences (P < 0.05) in N concentration were found by comparing the upper plant canopy with the lower. Expressed as crude protein (CP) the maximum value corresponded to that of the upper canopy at 92 DAP in November (19.0%), whereas the corresponding lower canopy value was only 4.72%. Based on its high biomass production and N accumulation, this legume could provide multiple beneficial effects when included in short crop rotations of sustainable production systems, taking advantage of the most favorable season and harvest stage. The present results suggest that 'Tropic Sun' planted in summer has good potential as a cover crop and green manure.

Grafting Melons Increases Yield, Extends the Harvest Season, and Prevents Sudden Wilt in New England

Melons (Cucumis melo var. reticulatis) are potentially a high value crop for New England, but production is limited by cool spring temperatures and sudden wilt. The sudden wilt syndrome in melon, attributed to both biotic and abiotic factors, is characterized by rapid wilting of vines either just preceding or during the harvest season, reducing melon quality and shortening the harvest period. We investigated the effects of grafting melons to rootstocks of interspecific hybrid squash (Cucurbita maxima × C. moschata), which have exhibited tolerance to soilborne diseases and cooler soil temperatures. In 2015, we compared the performance of ‘Halona’ melon grafted to two rootstocks, ‘Carnivor’ and ‘NH1320’, to that of nongrafted (NG) plants at two New Hampshire Agriculture Experiment Research Farms, Woodman (WRF) and Kingman (KRF). Pistillate flowering and melon harvests were 3 to 9 days earlier in NG than grafted (GR) plants. By harvest period, GR plant growth exceeded that of NG plants, and GR plants did not display wilting symptoms observed in NG plants. Total marketable yields were 57% and 90% higher for GR/‘Carnivor’ (47.8 and 45.0 Mg·ha−1) and 44% and 89% higher for GR/‘NH1320’ (43.9 and 44.9 Mg·ha−1) compared with the NG treatment (30.5 and 23.7 Mg·ha−1) at WRF and KRF, respectively. There were no differences in fruit numbers per plot between treatments, but mean fruit weight was between 33% and 71% larger in GR than NG treatments. In 2016, GR (‘NH1320’ rootstock) and NG ‘Halona’ were compared at three transplantation dates, 12 and 21 May and 1 June, and with two irrigation frequencies, drip irrigation every 2 days (2-d Irr) or every 4 days (4-d Irr). NG plants exhibited symptoms of sudden wilt in early August compared with no symptoms on GR plants. Harvests of NG melons were 3 to 8 days earlier than GR plants for all three planting dates. The increase in yields of GR plants compared with NG plants for the 12 and 21 May and 1 June planting dates were, respectively, 131%, 123%, and 149% greater with the 2-day Irr, and 93%, 100%, and 78% greater with 4-d Irr. Irrigation frequency did not significantly affect fruit size or soluble solids content (SSC), whereas grafting increased both fruit number and fruit size but did not significantly affect SSC at all three planting dates.

Effect of Vine Cuttingon Multiplication Ratio and Yield of Three Orange-fleshed Sweetpotato (<i>Ipomoea batatas</i> (L) Lam) Varieties in South Eastern Nigeria

A major constraint to sweetpotato production in Nigeria is the lack of clean and sufficient quantities of vine cutting at the time of planting in May or June. Inorder to obtain planting materials, farmers subject sweetpotato to vine harvest at various times but there is dearth of information on the effect of the level or intensity of defoliation on the crop. In this study, the response of three orange-fleshed sweetpotato varieties to cutting regimes in 2014 and 2015 cropping seasons in a tropical ultisol of South eastern Nigeria was evaluated. In each year, the experiment was laid out as 3 x 4 factorial arranged in randomized complete block design with three replications. Treatments comprised all combinations of three orange-fleshed sweetpotato varieties (Umuspo 1, Umuspo 3 and Ex-Igbariam) and four cutting regimes (6, 10 and 14 weeks after planting [WAP], 8 and 12 WAP, 10 and 14 WAP and no-cutting). Cutting regimes did not influence fresh shoot biomass in both year but cutting at 10 and 14 WAP significantly increased multiplication ratio compared to no-cutting or other cutting schedules. Storage root yield was, however, significantly higher with no-cutting than with the 4 weekly cuts, regardless of cutting dates. In all situations, Umuspo 1 produced significantly higher multiplication ratio and higher top and storage root yields than other varieties. Conversely, Umuspo 3 produced higher carotene yield at 10 and 14 WAP cutting compared to other varieties and cutting regimes.

Planting Date Effect upon Leaf spot Disease and Pod Yield across Years and Peanut Genotypes

ABSTRACT During 2012, 2015, and 2018 a set of 18 peanut (Arachis hypogaea L.) genotypes (some common and some different) were used to evaluate the effect of planting dates (April, May, and June) on leaf spot disease and pod yield. Within each year, the same genotypes were grown during the three planting dates at the Gibbs Farm near the University of Georgia, Coastal Plain Experiment Station, Tifton, GA using a randomized complete block design with five replications without fungicides or insecticides but with irrigation. Each year, significant differences (P≤0.05) were found among the genotypes within each of these three planting dates for leaf spot disease ratings (0-9 scale) and pod yields. ‘Georganic' in 2012 and 2015; and GA 132705, ‘Georgia-19HP', and ‘Georgia-14N' in 2018 had among the lowest leaf spot ratings. ‘Georgia-12Y' had the highest average pod yield for each year of the three years. Each year during this study, the April planting date had the lowest, and the June planting date had the highest leaf spot disease ratings. Percent coefficient of variation (CV) was consistently lower at the June planting date which suggest the least variability among the peanut genotypes. In the overall average of genotypes, the April planting date resulted in the highest pod yield and the June planting date had the lowest average pod yield. In summary, April planting dates resulted in the highest pod yields, and the lowest leaf spot ratings across each of the three years.