Winter Squash Research Articles

GWAS resolves molecular mechanisms underlying natural variation for carotenoids in Cucurbita maxima Duchesne

Carotenoid levels and composition are essential nutraceutical traits in Cucurbita maxima influencing the fruit flesh and rind colors. In this study, Mr Fugly, Boston Marrow, Baby Green Hubbard, Chicago Warted Hubbard, Golden Hubbard, and Bush Buttercup of USA; Australian Butter (Australia); Marmellata and Marina di Chioggia of Italy contained the highest carotenoid content. EMMAX (Efficient Mixed-Model Association eXpedited) was employed for a Genome-wide association study (GWAS) to identify associated genomic regions underlying the regulation of carotenoids. Here, we profiled the contents of α-carotene, β-carotene, β-cryptoxanthin, lutein, and zeaxanthin from a diversity panel of C. maxima consisting of classical horticulture groups including buttercup, turban, banana, zapallito, hubbard, mammoth and australian. Lutein and β-carotene were the major carotenoids among C. maxima accessions. Furthermore, we used genotyping by sequencing to identify 12,996 single nucleotide polymorphisms (SNPs) that were used to resolve population structure with three primary clusters and their admixed genotypes. Our GWAS revealed several SNPs related to 289 genes involved in plastid biogenesis, protein ubiquitination, transcriptional regulation at the carotenoid biosynthesis level, fruit ripening, and regulation of carotenoid transport. Together, these results contribute to a better understanding of the molecular mechanisms of carotenoid biosynthesis in fruit flesh and would facilitate breeding for enhanced carotenoids in winter squashes.

Cover crop-based reduced tillage management impacts organic squash yield, pest pressure, and management time

Cover crop-based reduced tillage (CCBRT) systems can provide multiple benefits in cucurbit cropping systems, including potential to reduce spread of soil-borne pathogens, minimize erosion, and decrease weed pressure. Despite benefits and farmer interest, adoption has been limited, in part due to inconsistent weed suppression and potential for reduced yields. Prior studies have suggested that N competition, allelopathy, and lower temperature may be factors in reducing vegetable yield in CCBRT systems. A strip tillage approach has been suggested as one strategy that could mitigate those issues, but cucurbit yields using these systems have shown mixed results in prior studies, some of which did not include other important considerations for growers such as the impact on weed and pest pressure. In 2018 and 2019, CCBRT strip till practices for organic acorn winter squash (Cucurbita pepo L.) production were assessed in Wisconsin on certified organic land. Combinations of different between-row (aisle) and in-row mulches were compared to attempt to identify reduced tillage combinations that effectively manage weeds while resulting in yields comparable to full tillage production, testing our hypothesis that no differences between production systems would be observed due to strip tillage and plastic mulch warming soil and minimizing competition while promoting cash crop growth. Aisle treatments included roller-crimped cereal rye (Secale cereale L.) mulch, straw mulch and cultivated bare ground, and in-row treatments included plastic mulch, ground straw mulch, and cultivated ground. Weed and pest counts, weed management time, and yields were compared between treatments. Plots managed with rye and straw in the aisles had significantly less weed pressure as compared to cultivated aisle treatments, although rye required more weed management time than ground straw mulch. In addition, rye resulted in lower marketable yield due to higher proportion unmarketable fruit in 2018, likely related to a 25 cm rain event 2 weeks prior to harvest. A significant row mulch × aisle mulch interaction was observed for marketable fruit m−1, showing that yield was not significantly affected by the type of in-row mulch in plots with crimped rye mulch in the aisle. Pressure from squash bugs (Anasa tristis) was also higher in treatments with organic or synthetic mulches (straw in aisles or rows, rye in aisles, and plastic in rows). Our results support previous evidence that crimped rye can be an effective mulching strategy to reduce weed pressure, with more efficient management than traditional straw mulch. However, crimped rye systems may have negative implications for yield and pest pressure regardless of the use of a strip-tillage approach, indicating that more research is needed to refine the production system.

First report of Fusarium ipomoeae and F. citri causing postharvest fruit rot of winter squash (Cucurbita maxima)

First report of Fusarium ipomoeae and F. citri causing postharvest fruit rot of winter squash (Cucurbita maxima)

Inheritance of traits related to yield and fatty acid profile of winter squash seed oil

The objective of this study was to determine the inheritance of traits related to seed oil yield and fatty acid profile components and to estimate the genetic relationships between these traits in Cucurbita moschata D. This study assessed six generations derived from crosses between parents with contrasting traits under study. F1 plants were obtained from the crossing between BGH 7319 (P1) and ‘Tronco Verde’ (P2), which were subsequently self-fertilized to obtain the F2 generation. F1 plants were also backcrossed with the P1 and P2 parents to obtain the BC1 and BC2 generations, respectively. In general, additive effects were predominant for most of the traits, and thus, the development of inbred lines is the recommended strategy for genetic improvement of these traits. Dominance effects were significant even under low expression. This demonstrates that the performance of progeny tests throughout the selfing generations will enable the distinction between genotypes, thus providing greater efficiency in selection and, consequently, greater genetic gains. In addition, overdominance was observed in oil content; therefore, the development of hybrids with genotypes causing high oil content is attainable. In general, the estimates of genetic correlations had a high magnitude and were favorable to the increase in functional oil productivity, associated with better quality of fatty acid profiles. Recurrent intrapopulation selection aimed at the development of open-pollinated varieties with high productivity, associated with greater stability of the functional oil in C. moschata, may be useful.

Characteristics of Interspecific Hybridization and Inbred Progeny of Pumpkin (Cucurbita moschata Duch.) and Winter Squash (Cucurbita maxima Duch.)

Hybrid incompatibility and F1 hybrid dysgenesis in the interspecific hybridization between pumpkin (Cucurbita moschata Duch.) and winter squash (Cucurbita maxima Duch.) have been previously noted. For this reason, it is difficult to obtain F2 generations due to F1 sterility. However, back-crossing and add-crossing can be utilized to overcome these incompatibility barriers in interspecific hybridization. To date, few studies have focused on parental selection, the back-crossing process, and offspring characteristics related to interspecific hybridization. Hence, we explored the F1 seed acquisition rate, plant characteristics, and F2 generation fertility after interspecific back-crossing and add-crossing hybridization of C. moschata and C. maxima. Moreover, as a female parent, X-1 (C. moschata) yielded F1 seeds when crossed with winter squash (C. maxima) 10-04-3, 10-37, or 10-05-2. BC1F1 seeds and plants could be obtained with winter squash (C. maxima) as the recurrent parent. Some healthy F2 seeds and plants were obtained from the interspecific hybrids, including ZJ-13, ZJ-8, and ZJ-11. Further fruit nutrition quality analysis showed that the starch, polysaccharide, cellulose, and dry material contents of ZJ-7 and ZJ-8 were significantly higher than those of the parent pumpkin and winter squash lines. The bioflavonoid content of ZJ-8 was lower than that of its parents, and its soluble protein was at the median value. Meanwhile, the bioflavonoid content of ZJ-1 was lower than that of its parents, but its soluble protein was significantly higher. These results suggest that back-crossing and multi-crossing can overcome the barriers to interspecific crossing of C. moschata × C. maxima. Some interspecific hybrid fruits had nutritional contents much higher than those of their parent lines. Additionally, X-1 (C. maxima) was found to act as a bridge species in interspecific hybridization. Collectively, in this study, the barriers to interspecific hybridization of C. moschata × C. maxima were addressed through crossing methods and choice of parents, and the obtained results are expected to provide novel support for interspecific hybrid breeding between C. moschata and C. maxima.

Identity and Pathogenicity of Fungi Associated with Root, Crown, and Vascular Symptoms Related to Winter Squash Yield Decline.

Winter squash (Cucurbita maxima cultivar Golden Delicious) produced in Oregon's Willamette Valley for edible seed production has experienced significant yield losses because of a soilborne disease. The symptoms associated with this disease problem include root rot, crown rot, and vascular discoloration in the stems, leading to a severe late season wilt and plant collapse. Through field surveys, Fusarium oxysporum, F. solani, F. culmorum-like fungi, Plectosphaerella cucumerina, and Setophoma terrestris were identified to be associated with diseased tissues, and each produced symptoms of root rot, crown rot, or stem discoloration in preliminary pathogenicity trials. In this study, 219 isolates of these species were characterized by molecular identity analyses using BLAST of the internal transcribed spacer and translation elongation factor 1 alpha genomic regions and by pathogenicity testing in outdoor, large-container trials. Molecular identity analyses confirmed the identity of isolates at 99 to 100% similarity to reference isolates in the database. In pathogenicity experiments, F. solani produced the most severe symptoms, followed by F. culmorum-like fungi, F. oxysporum, P. cucumerina, and S. terrestris. Some treatments of mixed-species inoculum produced symptom severity greater than what was expected from individual species. In particular, the mixture of F. culmorum-like fungi, F. oxysporum, and P. cucumerina and the mixture of F. culmorum-like fungi, F. solani, and S. terrestris had symptom ratings as high as that of F. solani by itself. Results indicate that this soilborne disease is caused primarily by Fusarium solani, but interactions between the complex of F. solani, F. culmorum-like fungi, F. oxysporum, and P. cucumerina can exacerbate disease severity.

Hatay İli Bazı Kabak (Cucurbitaceae) ve Tarlasarmaşığı'nda (Convolvuluceae) Fitoplazmaların Belirlenmesi ve Karakterizasyonu

Aims: During a disease survey conducted in 2019, typical symptoms including yellowing of the leaves, stunting, shortening of internodes, proliferation of auxiliary shoots (witches'-broom), the bunchy appearance of growth at the ends of stems (rosetting), virescence of flowers or sterility, phyllody, small and deformed leaves and fasciation were observed on suspected cucurbit plants growing in Hatay province. Therefore, this study was carried out to determine the phytoplasma infection(s) on cucurbit crops and bindweed in Hatay province of Turkey.Methods and Results: In total; 4 pumpkins (winter squash: Cucurbita moschata Duchesne), 12 summer squash (Cucurbita pepo L.) and 2 bindweed (Convolvulus arvensis L.) samples were collected from suspected plants in cucurbit fields in Hatay province. Some of the plants (2 pumpkins, 10 summer squash and 2 bindweeds) exhibited symptoms related to phytoplasmas. Total nucleic acid was extracted by CTAB method. PCR amplification of 16S rDNA with phytoplasma specific primer pairs; F1/R0 followed by R16F2n/R2 confirmed the phytoplasma presence. Expected size amplicons of ~1.2 kb were obtained from infected samples from symptomatic cucurbits (12/12) and bindweed (1/2), but not from asymptomatic cucurbit plants (0/4). The sequences of the 4 symptomatic samples were deposited in NCBI GenBank (MT163353, MT163393, MT163396, and MT163469).Conclusions: After sequencing and phylogenetic analyses it was revealed that the squash isolates had 99% sequence identity with “Candidatus phytoplasma trifolii” (16SrVI) and the bindweed isolate had 99% sequence identity with “Candidatus phytoplasma solani” (16SrXII).Significance and Impact of the Study: There is a lack of knowledge on the status of phytoplasma infections and natural hosts in cucurbits in Turkey. According to our knowledge, this is the first report of a member of 16SrVI group, Candidatus phytoplasma trifolii associated with phytoplasma infection in winter squash-pumpkin (C. moschata) and summer squash (C. pepo) in Turkey.

First report of Fusarium sambucinum causing postharvest fruit rot of winter squash (Cucurbita maxima)

First report of Fusarium sambucinum causing postharvest fruit rot of winter squash (Cucurbita maxima)

Heritability Estimates of L*a*b* Color Space Values in Winter Squash (Cucurbita spp.)

Carotenoids serve as protective antioxidants, and function in normal vision, bone growth, cell division and differentiation, and reproduction. Winter squash (Cucurbita spp.) is an excellent dietary source of carotenoids. The range of colors from yellow to red in Cucurbita species indicates that increasing carotenoid levels through plant breeding is possible. The objective of this research was to determine the heritability of flesh color in winter squash in both Cucurbita moschata Duchesne and Cucurbita pepo L. Segregating families representing F2, BC1P1 and BC1P2 populations were created in two families of C. pepo (‘Table Gold Acorn’ × PI 314806 and ‘Table King Bush’ × PI 314806) and one family of C. moschata (‘Butterbush’ × ‘Sucrine DuBerry’). Broad-sense heritabilities were calculated for the F2, BC1P1, and BC1P2 populations within each of the three families. Heritabilities ranged from 0.19 to 0.82 for L*, 0.28 to 0.97 for chroma, and 0.12 to 0.87 for hue across all families. Transgressive segregation for color space values L* was identified in the ‘Table King Bush’ × PI 314806 C. pepo population. Our results indicate that it is possible to breed for improved flesh color in Cucurbita, but the population size and number of test locations for evaluation need to be increased to provide better heritability estimates. Cucurbita species are grown throughout the world and their availability and low price makes them an important potential source of carotenoids for human nutrition and health for all ages.

The Quest for an Ideal Culinary Hyperlocalism

The Quest for an Ideal Culinary Hyperlocalism

First Report of Fusarium petroliphilum Causing Fruit Rot of Spaghetti Squash in California.

Spaghetti squash (Cucurbita pepo L. subsp. pepo) is a yellow-skinned squash that forms translucent spaghetti-like strands when cooked. California leads the nation in total squash production, the majority of which is grown in the San Joaquin Valley. In October of 2019, severe fruit rot of C. pepo L. subsp. Pepo (C. pepo) was observed in fruit harvested from seven cultivated fields in San Joaquin County, California. Infected fields incurred up to 30% postharvest losses. At harvest, fruit appeared healthy. After ten days in a shaded storage shed, scattered buff to tan ringed lesions extending into the flesh of infected fruits were observed. Lesions had visible sporodochia at the center that were variable in size and continued to expand in storage. Tissue (∼1 mm3) from the lesion margins of symptomatic fruit (n=8) was surface sterilized in 75 % ethanol for 1 min then 0.6% sodium hypochlorite for a minute, and aseptically transferred to half strength acidified potato dextrose agar (0.5 APDA) and incubated at 22-25 °C. Fungal colonies which grew from the pieces were light yellow, with mycelium that was flat and mucoid. Sporodochial conidia were falcate and robust with 3 to 5 septa and measured from 44.2 to 51.6 × 4.6 to 5.9 μm (average 46.3 × 5.2 μm). Aerial conidia were profuse, borne on short monophialides, ovoid to reniform, and measured 5.1 to 12.6 μm × 3.2 to 5.6 μm (average 4.2 × 6.1 μm). DNA extracted from two isolates, was amplified with primers ITS1/ITS4, and EF1-728F/EF1-986R using PCR, to obtain sequences from the internal transcribed spacer (ITS) (White 1990), and elongation factor 1α (EF1α) (Carbone et al. 1999) genetic regions. Sequences from both isolates were identical. Sequences from isolate MVAP50001827, GenBank nos. MZ081401 (ITS) and MZ102267 (EF-1α) matched 100% to sequences of representative isolates of Fusarium petroliphilum (Q.T. Chen & X.H. Fu; Short et al., 2013, MB 802539) from Cucurbita species, MF535516 (ITS) and MF580776 (EF-1α) respectively (González, V. et al. 2018). To fulfill Koch's postulates, conidia were harvested from a culture of isolate MVAP50001827 and grown for 7 days on 0.5 APDA at room temperature (22-25 °C). A 3-cc syringe with a 25-gauge needle was used to wound and inject 200 μl of 1 × 106 conidia ml-1 into three equally spaced points 1 mm deep into the rind of C. pepo fruit (n=4). C. pepo fruit (n=4) serving as negative controls were treated similarly with 200 μl of sterile deionized water. Fruit was incubated in a growth chamber at 27 °C under 12-h diurnal cycle lighting conditions. Ten days post inoculation, lesions densely covered with white sporodochia had expanded to 7 cm diameter and 5 cm deep on average (average fruit size 31×11 cm). Twenty days post inoculation, severe fruit rot was observed. F. petroliphilum did not grow from the controls, and was successfully reisolated from the symptomatic inoculated fruits, completing Koch's postulates. Seeds inside the inoculated fruits were completely colonized and covered in conidia. Twenty-five seeds from the source seed lot was tested for F. petroliphilum by surface sterilizing and plating onto 0.5 APDA. No F. petroliphilum grew from tested seed. Postharvest fungal diseases can affect profitability of winter squash, which is often held in storage, and sold when market prices are optimal. To our knowledge, this is the first report of Fusarium petroliphilum infecting spaghetti squash (Cucurbita pepo L. subsp. pepo) in California.

Silica Application Facilitates Vegetative Growth of Winter Squash (<i>Cucurbita maxima</i> L.) Under Water-Saving Irrigation

Silicon (Si) is used to alleviate abiotic stress in plants. Applying siliceous fertilizer in combination with regulated deficit irrigation may reduce water consumption during plant vegetative growth period. In this study, winter squash ‘East Elite’ was irrigated with 0.5, 1.0, and 1.5 mM SiO₂ under a field capacity—that is, the water content of 60% (C60, water-saving irrigation). The SiO₂ treatments promoted plant growth including stem diameter, plant height and leaf number; however, the plant growth under water-saving irrigation was slightly (but significantly) lower than that under regular irrigation (C₈₀). Silicon application in the water-saving irrigation can increase the accumulation of fresh and dry weight in the aboveground and underground of plant, but there is no significant difference between the treatments with different concentrations of silicon. Silicon application treatments was significantly higher chlorophyll content (SPAD) than C₆₀, and followed by C₈₀. The SiO₂ in the plants increased with increasing SiO₂ treatment concentration; however, the difference was nonsignificant. The 1.0 and 1.5 mM treatments increased the leaf transpiration rate and stomatal conductance. The growth of the plants treated with 1.5 mM SiO₂ was greater than that of the plants left untreated. The 1.5 mM SiO₂ treatment increased the activity of leaf catalase and peroxidase and reduced the leaf malondialdehyde content of the mild water stressed plants. Irrigation with a SiO₂ solution in a water-saving irrigation system can stabilize plant growth and increase water use efficiency.

Comparison of Photosynthetic Characteristics and Reproductive Traits of Winter Squash (<i>Cucurbita maxima </i>L.) Between Cultivars

The production of winter squash used vertical trellising was popular in the greenhouse for easy to manage growth and fruiting. This study investigated the photosynthetic characteristics of six winter squash cultivars to explore the differences in crop production efficiency between cultivars by vertical trellising cultivation. Plant growth, photosynthetic characteristics and fruit quality of winter squash cultivars ‘Black lamp’, ‘Tastemaker’, ‘East elite’, ‘Julius’, ‘Sugar’ and ‘Lyric’ were surveyed. The photosynthetic rate (Pn) was measured on the 70^th day after planting. We selected the three leaves above the fruit in which to compare the Pn between cultivars, and surveyed all leaves on ‘Black lamp’ and ‘East elite’ in order to make a comparison between nodes. The Pn values of ‘Black lamp’, ‘East elite’, ‘Lyric’ and ‘Tastemaker’ were significantly higher, at 14.02, 13.06, 12.33 and 12.19 μmol CO₂/m²∙s, respectively. The Pn of the leaves on 5–8^th nodes decreased significantly, and the Pn of the 1^st–5^th nodes up to the fruit also decreased. With regards to reproductive traits, the first pistillate flowers of ‘East elite’ and ‘Black lamp’ bloomed on the 30^th day after planting, while the other cultivars bloomed on the 35–37^th day after planting. The six cultivars were classified according to the size of the fruit on the 48^th day after pollination: ‘Lyric’ and ‘Tastemaker’ were classified into the largest group, at 1203 and 1106 cm³, respectively; the second group contained ‘East elite’ and ‘Julius’, at 870 and 687 cm³; while ‘Sugar’ and ‘Black lamp’ were in the smallest group, at 353 and 217 cm³, respectively. The soluble sugar and total soluble solid (TSS) contents of ‘East elite’ were significantly elevated, their values being 630.6 g/kg and 13.3%, respectively. The starch content of ‘Lyric’ was the highest at 193.7 g/kg. "Black Light" was a fruit-number type, and the increase in fruit number could increase the yield/plant; "East elite" was a fruit-weight type, and the yield per plant was related to the weight of a single fruit. The influence of the unit leaf of “Black Lamp” on the fruit fresh weight was the lowest performance in the reproductive growth. In order to increase productivity of small fruit such as ‘Black lamp’ western pumpkin, the balance between the vegetative growth and the reproductive growth was necessary to be improved.

Minor Pathogens Causing Fruit Rot of Winter Squash during Storage

Minor Pathogens Causing Fruit Rot of Winter Squash during Storage

Inheritance of Traits Related to Yield and Fatty Acid Profile of Winter Squash Seed Oli

Inheritance of Traits Related to Yield and Fatty Acid Profile of Winter Squash Seed Oli

Identification of high seed oil yield and high oleic acid content in Brazilian germplasm of winter squash (Cucurbita moschata D.)

Cucurbita moschata D. seed oil contains approximately 75% unsaturated fatty acids, with high levels of monounsaturated fatty acids and antioxidant compounds such as vitamin E and carotenoids, constituting a promising food in nutritional terms. In addition, the Brazilian germplasm of C. moschata exhibits remarkable variability, representing an important source for the genetic breeding of this vegetable and other cucurbits. The present study evaluated the productivity and profile of the seed oil of 91C. moschata accessions from different regions of Brazil maintained in the Vegetable Germplasm Bank of the Federal University of Viçosa (BGH-UFV). A field experiment was conducted between January and July 2016. The accessions showed high genetic variability in terms of characteristics related to seed oil productivity (SOP), such as the weight of seeds per fruit and productivity of seeds, providing predicted selection gains of 29.39 g and 0.26 t ha−1, respectively. Based on the phenotypic and genotypic correlations, a greater SOP can be achieved while maintaining a high oleic acid concentration and low linoleic acid concentration, providing oil of better nutritional and chemical quality. In the variability analysis, the accessions were clustered into five groups, which had different averages for SOP and fatty acid concentration of seed oil, an approach that will guide the use of appropriate germplasm in programs aimed at genetic breeding for SOP and seed oil profile. Per se analysis identified BGH-4610, BGH-5485A, BGH-6590, BGH-5556A, BGH-5472A, and BGH-5544A as the most promising accessions in terms of SOP, with an average (μ + g) of approximately 0.20 t ha−1. The most promising accessions for a higher oleic acid concentration of seed oil were BGH-5456A, BGH-3333A, BGH-5361A, BGH-5472A, BGH-5544A, BGH-5453A, and BGH-1749, with an average (μ + g) of approximately 30%, almost all of which were also the most promising in terms of a lower linoleic acid concentration of the seed oil, with an average (μ + g) of approximately 45%. Part of the C. moschata accessions evaluated in the present study can serve as a promising resource in genetic breeding programs for SOP and fatty acid profile, aiming at the production of oil with better nutritional and physicochemical quality.

How to save a landrace from extinction: the example of a winter squash landrace (Cucurbita maxima Duchesne) in Northern Italy (Lungavilla-Pavia)

How to save a landrace from extinction: the example of a winter squash landrace (Cucurbita maxima Duchesne) in Northern Italy (Lungavilla-Pavia)

Structural characteristics and physicochemical properties of starches from winter squash (Cucurbita maxima Duch.) and pumpkin (Cucurbita moschata Duch. ex Poir.)

Winter squash (Cucurbita maxima Duch.) and pumpkin (Cucurbita moschata Duch. ex Poir.) are widely consumed in the world. Empirical evidences showed that their cooked texture was related to the starch content and probably starch properties. In this study, starches were extracted from 2 winter squash cultivars (Yinli and Heili) and 1 pumpkin cultivar (Miben) popularly cultivated in China. The mature fruits of three cultivars contained 1.05–6.47% (fresh weight) starch with different granule sizes (d (0.5) 9.51–15.18 μm). Starches from winter squash and pumpkin had polyhedral and spherical shape granules with amylose content varied from 21.35% to 30.17%. All starches exhibited B-type crystalline structure. The relative crystallinity ranged from 26.15% to 31.31%, and the IR absorbance ratios of 1022/995 cm−1 and 1045/1022 cm−1 ranged from 0.759 to 0.806 and from 0.565 to 0.607, respectively, among 3 cultivars. SAXS pattern indicated 9.59–9.80 nm DBragg for these starches. The Mw was highest (5.03 × 107 g/mol) in Miben starch but lowest (3.64 × 107 g/mol) in Heili starch. All starches had identical amylopectin branch chain distributions but varied in average chain length and fb1 and fb2 chains. The gelatinization temperature (To, Tp, Tc) and enthalpy change (ΔH) were lowest in Heili starch and highest in Miben starch. The peak, trough, final and setback viscosities varied from 4468 to 6266 cP, 3116 to 4259.5 cP, 4075 to 6073 cP, and 787 to 1813 cP, respectively. All starch granules showed strong resistance to enzymatic hydrolysis. Yinli and Miben starches had higher RS content in starch pastes and retrograded gels than Heili starch.

EVALUATION OF GRAFTING USING CUCURBIT INTERSPECIFIC HYBRIDS TO CONTROL FUSARIUM WILT IN CUCUMBER

Grafting is a safe agro-technique used to boost tolerance against biotic and abiotic stresses and increase crop yield and quality. This study was undertaken to control cucumber Fusarium wilt through grafting onto novel Cucurbit interspecific hybrids and assess their effect on nutrients, defense enzymes in cucumber, and root characteristics. Four crosses were done between two lines of each of Bottle Gourd (Lagenaria siceraria), Winter squash (Cucurbita maxima), Winter squash (C. moshata), and Wild cucumber (C. zambinus). The commercial hybrid rootstock Supper Shintosa was also considered. Results indicated that all hybrid rootstocks, except Bottle Gourd, exhibited a significant decrease in Fusarium wilt severity compared with non-grafted control. Plant height and shoot dry weight of grafted plant were higher than those of the nongrafted control with best results for grafting onto C. moshata. The macro (N, P, K, Ca, and Mg%) and micro (Fe and Zn ppm) nutrient contents in the leaf of grafted plants were more than those of the nongrafted control. The highest macro and micronutrient contents were observed due to grafting onto C. moshata followed by C. maxima. Grafting of cucumber onto resistant rootstocks exhibited a significant increase in activity of peroxidases and polyphenoloxidase enzymes. Furthermore, grafting onto all rootstocks, except C. zambinus, caused an increase in root diameter more than the nongrafted control. Grafted cucumber onto C. maxima rootstock showed the best values in terms of diameter of the root, thickness of the cortex, dimension of vascular bundle, mean diameter of the vessel, and the pith over the nongrafted control.

Study of interval infrared Airflow Drying: A case study of butternut (Cucurbita moschata)

Interval process is defined as a means of operating short-time intervals configured to allow the material to attain characteristics to match higher drying rate. The innovative Interval Infra-Red Airflow Drying (IIRAD) involves successive heating intervals (tON) of several seconds followed by tempering periods (tOFF) of a few minutes. IIRAD provides heat only when the product surface is fully rewetted. Drying of winter squash slices was performed in three cases; continuous IR-drying, IIRAD-I: tON = 5 s and tOFF = 2 min, and IIRAD-II: tON varies throughout the process with tOFF = 2 min. A higher drying rate was observed during IIRAD-I. Measured evaporating-bulb temperatures were below 21 °C with energy consumption of 0.98 and 0.77 kWh/kg of evaporated water for I-IIRAD and II-IIRAD, respectively, wherein they exceeded 66 °C and 2.19 kWh/kg of evaporated water for continuous drying. IIRAD resulted in better preservation of flavonoids and better retention of color. However, continuous IR-dried samples displayed better rehydration and higher total polyphenol content. Overall, IIRAD is shown to be a promising drying technique for heat sensitive materials in terms of efficiency, energy consumption, and preservation of key quality attributes linked to lower operating temperature, but with increased drying time.