Zucchini Plant Research Articles

Dieldrin accumulation, distribution in plant parts and phytoextraction potential for several plant species and Cucurbita pepo varieties

Dieldrin, an organochlorine pesticide (OCP) widely used for crop protection in the second half of the 20th century till the 70's, is worldwide still present in arable soils. It can be transferred to crops, notably cucurbits, depending on plant species and cultivars. Finding strategies to decrease OCP bioavailability in soil is therefore a main concern. Phytomanagement strategies could provide (i) ready-to-use short term solution for maintaining the production of edible plant parts with dieldrin concentrations below the Maximum Residue Limits (MRL) and (ii) long-term solution for dieldrin phytoextraction reducing progressively its bioavailability in the soil. This field study aimed at determining dieldrin accumulation capacities and allocation pattern in 17 non-Cucurbitaceae species and 10 Cucurbita pepo varieties, and assessing the dieldrin phytoextraction potential of these plant species when grown to maturity in a historically dieldrin-contaminated soil. Out of the non-Cucurbitaceae species, vetiver was the only one able to accumulate significant amounts of dieldrin, which mainly remained in its roots. All C. pepo varieties were able to uptake and translocate high dieldrin amounts into the shoots, leading to the highest phytoextraction potential. Despite the intraspecific variability in dieldrin concentration in zucchini plant parts, mainly in the reproductive organs, the phytoextraction capacity for shoots and fruits was high for all tested varieties (147 to 275 μg dieldrin plant−1, corresponding to 5.6 % of the n-heptane extractable soil dieldrin), even for the one with low fruit dieldrin concentration. Both food safety and phytoextraction could be achieved by selecting productive zucchini varieties displaying low dieldrin concentration in fruits and high one in shoots.

Effects of Addition of Humic and Fulvic Acids on Soil Properties and Germination Percentage of Cucurbit Plants (Zucchini and Cucumber)

This research was conducted to study the effect of adding humic and fulvic acids to the irrigation water on soil properties and germination percentage of two cucurbit plants: zucchini and cucumber. The study was conducted in an open field in Sokhna District in the governorate of Zarqa (Jordan). The field soil was transported to calcareous sandy soil. In the beginning, the weeds and stones were removed, and the land was smoothed and plowed. Effort was made to control weeds and insects at all stages of plant growth. Then, an irrigation network was installed. The fulvic acid-humic acid (FA-HA) biostimulant mixture was incorporated with the irrigation water, and irrigation was practiced three days per week for four weeks. During this period, every irrigation round lasted for two to three hours. A mixture of humic acid (8.0%) and fulvic acid (8.0%) was added to the irrigation water. Three treatments were considered, corresponding to three acid mixture concentrations: 0.50 mL.L-1, 1.00 mL.L-1, and 1.50 mL.L-1. The acid mixtures were added continuously at all stages of plant growth until plant maturity and harvest. Four replicates of the experiment were made. The plant growth variables of interest were germination percentage, number of leaves, date of fruition, size of fruit, and overall mass of fruits. Meanwhile, the soil parameters of interest were soil pH and soil salinity (electric conductivity (EC)) before and after adding the FA-HA mixture. The study found that the 0.5 mL.L-1 acid mixture treatment led to the early growth of the zucchini plant seeds and that fruition took place 12 days after planting. In addition, the results showed an increase in plant germination under the 0.5 mL.L-1 acid mixture treatment in light of the increase in the number of male and female plant flowers, with fruiting taking place on time. In conclusion, the relationship between zucchini growth and yield with FA-HA mixture concentration is non-linear. It is also concluded that the optimum acid mixture concentration and application rate are crop-specific. Hence, for each crop, the most appropriate acid mixture concentration should be determined first before the broad-scale application of amendments to the soil to ensure the contribution of this environmentally friendly practice to sustainable agriculture.

Exploring the Chemical Composition of Female Zucchini Flowers for Their Possible Use as Nutraceutical Ingredient.

The zucchini (Cucurbita pepo L.) plant is well known for its fruits; however, its edible flowers appear to contain several active molecules, including polyphenols, which display poor bioaccessibility after gastrointestinal digestion (GiD). This study explores the bioaccessibility of polyphenols and antioxidant capacity within zucchini flower extracts during simulated GiD. Two nutraceutical formulations, non-acid-resistant (NAcR) and acid-resistant (AcR) capsules containing an aqueous extract of zucchini flowers, were employed in this investigation. Additionally, high-resolution mass spectrometry (Q-Orbitrap HRMS) was utilized for a comprehensive analysis of their polyphenolic constituents. Predominantly, rutin and isorhamnetin-3-rutinoside were the most prevalent compounds detected in the samples (514.62 and 318.59 mg/kg, respectively). Following in vitro GiD, the extract encapsulated in AcR capsules exhibited enhanced bioaccessibility during both the duodenal (189.2 and 162.5 mg GAE/100 g, respectively) and colonic stages (477.4 and 344.7 mg GAE/100 g, respectively) when compared with the extract encapsulated in NAcR capsules. This suggests that gastric acidity adversely impacted the release of polyphenols from NAcR capsules. In conclusion, the aqueous zucchini flower extract emerges as a promising and readily accessible source of dietary polyphenols. Moreover, the utilization of AcR capsules presents a potential nutraceutical formulation strategy to improve polyphenol bioaccessibility, enhancing its applicability in promoting health and well-being.

Daya Adaptasi Lalat Buah (Bactrocera calumniata H.) pada Tanaman Inang Cucurbitaceae pada Dataran Tinggi di Bali

Adaptability of Fruit Flies (Bactrocera calumniata H.) to Cucurbitaceae Host Plants in the Highlands of Bali. Plants from the Cucurbitaceae family are one of the host plants for fruit flies. Plants grow in the highlands and lowlands. One of the pests of the Cucurbitaceae family is Bactrocera calumniata. Symptoms of fruit attacked by B. calumniata are having small holes that ooze fluid caused by the puncture of the ovipositor of female fruit flies and fruit that is attacked after a long time becomes soft in texture and smells rotten. The research was conducted in Candikuning Village, Tabanan Regency and Pancasari Village, Buleleng Regency, Bali Province. Based on research showed that zucchini and cucumber were attacked by fruit flies of the type B. calumniata. Abundance of population, percentage of females, and percentage of damage were more on zucchini plants than cucumber plants. So the adaptability of the fruit fly B. calumniata is better in the zucchini plant compared to the cucumber plant.

Antibiotic-resistant bacteria in hospital wastewater treatment plant effluent and the possible consequences of its reuse in agricultural irrigation.

Wastewater from hospitals should be monitored precisely and treated properly before discharge and reuse to avoid epidemic and pandemic complications, as it contains hazardous pollutants for the ecosystem. Antibiotic residues in treated hospital wastewater effluents constitute a major environmental concern since they resist various wastewater treatment processes. The emergence and spread of multi-drug-resistant bacteria, that cause public health problems, are therefore always a major concern. The aims and objectives of this study were mainly to characterize the chemical and microbial properties of the hospital effluent of wastewater treatment plant (WWTP) before discharge to the environment. Special attention was paid to the presence of multiple resistant bacteria and the effects of hospital effluent reuse in irrigation on zucchini as an economically important plant. The risk of cell-free DNA carrying antibiotic resistance genes contained in the hospital effluent as a long-lasting hazard had been discussed. In this study, 21 bacterial strains were isolated from the effluent of a hospital WWTP. Isolated bacteria were evaluated for multi-drug resistance ability against 5 antibiotics (Tetracycline, Ampicillin, Amoxicillin, Chloramphenicol, and Erythromycin) at a concentration of 25 ppm. Out of them, three isolates (AH-03, AH-07, and AH-13) were selected because they recorded the highest growth in presence of tested antibiotics. Selected isolates were identified using 16S rRNA gene sequence homology as Staphylococcus haemolyticus (AH-03), Enterococcus faecalis (AH-07), and Escherichia coli (AH-13). Their susceptibility to ascending concentrations of tested antibiotics indicated that they were all susceptible at a concentration above 50 ppm. Results of the greenhouse experiment regarding the effect of hospital WWTP effluent reuse on zucchini plant fresh weights compared to that irrigated with fresh water indicated that the former recorded a limited increase in total fresh weights (6.2 g and 5.3 g/plant, respectively). Our results demonstrated the low impact of the reuse of Hospital WWTP effluent in agriculture irrigation compared to its greater risk in transferring multiple antibiotic bacteria and antibiotic resistance genes to soil bacteria through natural transformation.

Pengaruh pemberian pupuk bioboost terhadap pertumbuhan dan hasil tanaman zukini (Cucurbita pepo L.) varietas Zacky Z-6

Zukini (Cucurbita pepo L.) belongs to the pumpkin tribe (Cucurbitaceae) including annual plants that live in the highlands. The need for zucchini in Indonesia is increasing along with the growing number of restaurants serving Japanese and Korean dishes. Information about the cultivation of zucchini in Indonesia is still limited, so that zucchini is rarely found among farmers. The purpose of the experiment was to get the right concentration of Bioboost fertilizer in order to give maximum zucchini yields. The experiment was conducted from February to April 2022 in Cihanjuang Rahayu Village, Parongpong, West Bandung Regency, West Java Province with an altitude of 1.243 m above sea level. The experiment menthod used complete randomized block design (CRBD) of five treatment and five replications. Each treatment consisted of 5 plants. so the total number was 125 plants. Treat the experiment A : 0 cc Bioboost/liter of water, B : 20 cc Bioboost/liter of water, C : 40 cc Bioboost/liter of water, D : 60 cc Bioboost/liter of water, E : 80 cc Bioboost/liter of water. The results showed that the concentration of Bioboost fertilizer was effective on the number of leaves, age of flower initiation, number of fruit/plant, fruit length/plant, fruit diameter/plant and fruit weight/plant. 
 The application of Bioboost with a concentration of 60 cc/liter of water had the best effect on the growth and yield of the varieties Jacky Z-6 zucchini plant

First Report of Cucurbit Chlorotic Yellows Virus Infecting Watermelon and Zucchini in the Canary Islands, Spain.

In July 2019, eleven watermelon (Citrullus lanatus) plants, six 'Augusta negra' and five 'Kasmira', and seven zucchini (Cucurbita pepo) 'Marcado' plants showing yellowing and vein clearing on the leaves were collected in Arico, in Tenerife Island of the Canary Islands. Analysis with enzyme-linked immunosorbent assay (ELISA) with polyclonal antibodies using kits from (LOEWE® Biochemica GmbH, Sauerlach, Germany) detected cucurbit chlorotic yellows virus (CCYV) in four watermelon (two 'Augusta negra' and two 'Kasmira') plants and one zucchini plant. Reverse transcription-polymerase chain reaction (RT-PCR) with primers CCYV-CPs (5'-ATGGAGAAGACTGACAATAAACAA-3') and CCYV-CPas (5'-TTTACTACAACCTCCCGGTG-3') (Hamed et al. 2011) yielded 750 bp DNA fragments, which were purified, and directly sequenced by Sanger sequencing. The four CCYV sequences obtained from watermelon plants were identical and showed a 99.6% nucleotide identity with the CCYV isolate from Zucchini. The nucleotide sequences of CCYV isolates 351/19 from watermelon and 361/19 from zucchini were deposited in GenBank under accessions OK562588 and OK562589, respectively. BLASTn analysis showed high nucleotide identity, greater than 99 % with most worldwide CCYV isolates (AB523789, HM581658, JF502222, JF807053, JN126045-6, JQ904629, JX014262, KC990503-5, KC990507, KJ735450, KJ149806, KT946809, KT946816, KU507602, KX118632, KY400632-4, KY618799, LT716000, LT716003-4, MH477612, MH806868, MH819191, MN529560, MN815012-3, MT396249 MT048669, MW033301, MW584337, MW251342, MW521380, MW521381, MW584335-6, MW629380, MZ325848-9 and MZ405664), about 98% with two Saudi Arabian isolates (KT946810 and KT946815) and about 95 % with three Iranian isolates (KC577201-3). These genetic relationships were confirmed with a phylogenetic tree (Supplementary Fig. 1) inferred with the maximum likelihood method with 500 bootstrap replicates and the nucleotide substitution model HKY+G implemented in the program MEGA-X (Kumar et al., 2018). There is no correlation between geographic distance and genetic distance. CCYV is related to viruses in the genus Crinivirus, family Closteroviridae (Okuda et al., 2010). It is widespread and causes high economic losses (yield reduction and unmarketable fruits) in cucurbit crops from East Asia: Japan, China, Taiwan and South Korea; North America (the USA states of California, Texas, Georgia and Alabama); Middle East: Sudan, Saudi Arabia and Iran; and the Mediterranean basin: Egypt, Israel, Lebanon, Turkey, Greece, Algeria and peninsular Spain (Kheireddine et al., 2020; Chynoweth et al., 2021; Jailani, et al., 2021; Kwak et al., 2021). This is the first report of CCYV infecting cucurbits in the Canary Islands. The emergence of this virus poses a threat to the cucurbit crops in the Canary Islands and requires control measures to prevent its spread in Tenerife and the other Canary Islands.

Role of nozzle type and certain adjuvants in reducing application rates of imidacloprid and spirotetramat against whitefly, Bemisia tabaci (Gennadius) on zucchini plant.

Role of nozzle type and certain adjuvants in reducing application rates of imidacloprid and spirotetramat against whitefly, Bemisia tabaci (Gennadius) on zucchini plant.

Ionic homeostasis, biochemical components and yield of Italian zucchini under nitrogen forms and salt stress.

This research was carried out aiming at evaluating the effects of nitrate and ammonium ions on nutrient accumulation, biochemical components and yield of Italian zucchini (cv. Caserta) grown in a hydroponic system under salt stress conditions. The experiment was carried out in a greenhouse utilizing an experimental design in randomized blocks, arranged in a 2 x 5 factorial scheme, with 4 replications. The treatments consisted of two forms of nitrogen (nitrate - NO3- and ammonium - NH4+) and 5 electrical conductivity levels of irrigation water (ECw) (0.5, 2.0, 3.5, 5.0 and 6.5 dS m-1). The analysis of the results indicated that supply of N exclusively in NH4+ form promotes greater damage to the leaf membrane and reduction in accumulation of macronutrients and higher Na+/K+, Na+/Ca++ and Na+/Mg++ ratios in the shoots of zucchini plants. Electrical conductivity of irrigation water above 2.0 dS m-1 reduces the accumulation of nutrients in shoot and yield of Italian zucchini plant. The toxicity of NH4+ under Italian zucchini plants overlap the toxicity of the salinity, since its fertilization exclusively with this form of nitrogen inhibits its production, being the NO3- form the most suitable for the cultivation of the species.

Comparative analysis of the antioxidant compounds of raw edible flowers and ethanolic extracts of Cucurbita pepo , Tagetes erecta , and Erythrina americana during storage

This work determined the antioxidant compounds of the raw flowers of the zucchini plant, Mexican marigold, and colorin and their ethanolic extracts, which were stored by 270 days for their potential use as functional food. The DPPH• radical scavenging capacity was in a range of 50%–95% for the three raw flower species, but the ethanolic extracts of flowers (EEF) of the zucchini plant and colorin lost up to 80% of these compounds. The total phenols of raw flowers and EEF were of 0.3–2.5 mg gallic acid equivalents (GAE)/g. The total flavonoids were up to 85% higher in the EEF of the nondehydrated Mexican marigold than in the raw flowers. In the remaining treatments, there had no notables changes (~0.5 mg quercetin/g). Rutin, quercetin, myricetin, and lucenin were in the EEF of the nondehydrated samples. In conclusion, EEF of nondehydrated Mexican marigold showed higher antioxidant composition than remaining extracts. Practical applications This study demonstrates the presence of antioxidant compounds in three edible flowers produced worldwide for ornamental and industrial purposes, except in Mexico, where they are endemic plants and are also consumed as food. Antioxidant compounds of the evaluated edible flowers can be found in nondehydrated samples and dehydrated, and they can be extracted and preserved for 270 days using cane alcohol as the solvent.

Chitosan-modified biochar immobilised arsenic in root medium and enhanced the growth of zucchini (cv. Courgette d’Italie) seedlings

Contamination of arsenic (As) presents a health hazard that affects home gardeners neighbouring contaminated environments. The use of chitosan-modified biochar was investigated to immobilise As(V) from aqueous solution and zucchini seedlings (cv. Courgette d’Italie) were grown as a test crop. The results of characterisation revealed that the presence of chitosan on biochar (BR) surface improved its efficiency of As(V) immobilisation from the contaminated environment. A sorption study further showed that compared with the BR, (BR-C) chitosan-modified biochar (0.1 g) depicted the increased immobilisation of As(V) (10 ppm) from solution. Both Langmuir and Freundlich models fitted well, showing monolayer as well as multilayer sorption. BR-C showed a high Langmuir arsenic sorption capacity of 57.83 mg/g, which effectively decreased the level of As(V) toxicity. As demonstrated in results, As-stress reduced plant growth, seedling length, photosynthetic pigments, soluble sugar, increased hydrogen peroxide contents, and electrolyte leakage percentage. Simultaneously, BR and BR-C were effective against As(V) stress-induced changes in the zucchini plant. Collectively, the results of this study indicate that the modification of BR with chitosan can efficiently immobilised arsenic in the root medium and enhance growth of zucchini under controlled conditions by reducing the uptake of As(V).

Initial growth of zucchini irrigated with saline water in soil with biofertilizers

Zucchini culture is slightly sensitive to salinity and is among the ten vegetables of highest economic value, with characteristics of precocity and easy cultivation. These characteristics are some of the reasons for the expansion of its cultivation among small producers. Thus, the objective was to evaluate the effect of different levels of salinity in the irrigation water and biofertilizer types on the initial growth of the zucchini (Cucurbita pepo L.) culture. The experiment was carried out in the full sunlight in a randomized block design, in a 5x2 factorial arrangement. The treatments consisted of a combination of five types of biofertilizers (quail, sheep, mixed, bovine, and crab) and two salinity levels of the irrigation water (0.8 and 2.5 dS m-1), with five replicates. At 30 days after transplanting, the following variables were evaluated: electrical conductivity of the substrate, plant height, number of leaves, roots length, stem diameter, leaf area, chlorophyll content, dry mass of the aerial part, root dry mass, and total dry mass. Salt stress negatively interferes with the accumulation of zucchini plant biomass. Quail, bovine, and sheep biofertilizers are more efficient about plant height, number of leaves, and stem diameter. The sheep biofertilizer attenuates the salt stress for the dry mass of the aerial part, the root, and the total dry mass.

Foliar spray with sodium hydrosulfide and calcium chloride advances dynamic of critical elements and efficiency of nitrogen metabolism in Cucurbita pepo L. under nickel stress

The current study sought to explore the effects of leaf spray with sodium hydrosulfide (NaHS) and calcium chloride (CaCl2) on the growth, the content of essential elements, and nitrogen metabolism in zucchini plants under normal and nickel (Ni) stress conditions. The 10-day old zucchini plants were exposed to Ni concentrations (0, 50, and 100 mg L−1) for 15 days. The results showed that both Ni levels reduced the fresh and dry weights of roots and shoots, leaf area, leaf water content and decreased the content of photosynthetic pigments due to the Ni accumulation and depletion of essential elements in tissues. Moreover, Ni stress increased electrolyte leakage (EL) and decreased the total protein content, the activities of catalase (CAT) and nitrate reductase (NR) in the leaves of the zucchini plant. Foliar spray with NaHS (100 μM) and CaCl2 (15 mM) alone or combined improved growth parameters and the content of chlorophyll a, b and carotenoids under non-stress and Ni stress conditions. Leaf spray with NaHS and CaCl2 and especially their combined application reduced the accumulation of Ni in the roots and shoots, lessened Ni uptake and the translocation factor values in plants, lowered EL and increased CAT activity in leaves. Foliar spray with NaHS and/or CaCl2 improved the homeostasis of macro- and micro-nutrients (N, P, K, Ca, Mg, Fe, and Cu) in the roots and shoots, increased the total protein content and enhanced the NR activity in leaves of zucchini plants under Ni stress. These novel results indicated that the interactive effect of H2S and Ca2+ not only alleviates oxidative stress but also contributes to maintaining nutrient homeostasis and efficiency of N metabolism in plants.

Genomic sequence variability of an Italian Zucchini yellow mosaic virus isolate

Zucchini yellow mosaic virus (ZYMV) was first reported in Italy, but no Italian isolates have been sequenced so far. A ZYMV isolate, designated Z104, was isolated from a zucchini plant grown in the open field in Piedmont, Italy, and showing severe disease symptoms. We report the full-length genome sequence of Z104 as determined by Sanger sequencing and small (s)RNA deep sequencing. The latter technique was useful to confirm the isolate sequence, that was deposited in the NCBI database with the accession number MK956829 and to investigate the sequence variability of Z104 isolate. The genome of 9611 nucleotides (nt) consisted of an open reading frame of 9243 nt encoding a polyprotein of 3080 amino acids (349.88 kDa), flanked by the 5′- and 3′-untranslated regions, and an overlapping ORF of 74 amino acids, the P3N-PIPO. As in previously sequenced ZYMV isolates, Z104 polyprotein consists of 10 putative functional proteins. Several domains in the HC-Pro and P3 proteins related to the transmissibility by aphids and virus aggressiveness are conserved in Z104. Symptoms induced both in the field and laboratory by Z104 together with its molecular features indicate that it is an aggressive strain. Deep sequencing of sRNAs revealed a particularly high variability in the genome sequence at eight nucleotide positions, three of which resulted in missense mutations in the P3, 6K1, and NIb proteins. This may be indicative of the natural ZYMV genome variability within the host. The phylogenetic analysis of the whole genome or the sole coat protein of several ZYMV isolates did not provide evidence for a close relationship of Z104 with other isolates from European countries. To the best of our knowledge, this is the first-reported complete genome of a ZYMV isolate from Italy.

Identification of suitable media based on hydroponic culture for production Zucchini squash

An experiment was conducted to identify the hydroponic culture based suitable media for the production of Zucchini Squash in the Biochemistry Laboratory, Patuakhali Science and Technology University, Dumki, Patuakhali, Bangladesh during 2014. Zucchini plant (Cucurbita pepo L.) were grown in closed soilless systems to determine the effect of four different hydroponics media on plant growth, yield and nutrient contents (fruit moisture content, ascorbic acid content on fruit, fruit protein content, protein content in leaves). Three types of substrates (coconut husk, jute, cotton) along with Hoagland solution were used in this experiment. Result revealed that media using Jute fiber showed significant effect on plant growth and nutritional values than the other media (media of cotton with Hoagland solution, coconut husk with Hoagland solution and only Hoagland solution). The plant grown using jute media showed the highest plant height (60.33 cm), number of leaves (17.33), yield (1.5 kg plant-1), fruit moisture content (97.33%), Ascorbic acid content in fruit (28.73 mg 100g-1), protein percentage in fruit (1.406%) and percentage (1.326%) in leaves than the other media. Therefore, with the controlled nutrient supply, less expense, less labor, no use of pesticides or fertilizer with controlled environment the use of jute fiber as a substrate with Hoagland solution can be an effective one.Int. J. Agril. Res. Innov. & Tech. 6 (2): 1-4, December, 2016

Growth and yield of zucchini squash (Cucurbita pepo L.) as influenced by a sunn hemp living mulch

The use of living mulches for managing crop pests has received much attention recently but their effects on primary crop productivity is relatively uninvestigated. This study investigated the influence of a sunn hemp (Crotalaria juncea L.) living mulch on growth, development and yield of zucchini squash (Cucurbita pepo L.). Field experiments were conducted at two locations during three growing seasons. Zucchini squash growth, dry biomass and yield were recorded and compared when inter-planted into a companion sunn hemp living mulch (SH) and grown in monoculture [bare-ground (BG)]. During the first and second study years, when sunn hemp was cut to a height of 45 cm and used concurrently as a living and surface mulch, zucchini plant dry biomass and yield were substantially reduced compared with BG habitats. However, in the third year, when sunn hemp was cut to a shorter height of 20 cm, zucchini plant growth and yield were similar between treatments at one study site and significantly greater in SH than in BG habitat at the other site. Potential causes of yield differences and implications of using sunn hemp as a living companion plant are discussed.

Evaluation of adjuvants for enhanced management of Podosphaera xanthii using potassium silicate and biocontrol agents

Three adjuvants [polyether-polymethylsiloxane-copolymer (Break-Thru®), alkoxylated fatty alkylamine polymer/ethoxylated sorbitane ester (Partner 650®) and polyoxyethylene 20 sorbitan monooleate (Tween-80®)] were compared for their ability to improve the efficacy of potassium silicate and biocontrol agents (BCAs) against powdery mildew of zucchini caused by Podosphaera xanthii (Castagne) U. Braun & Shishkoff. The most effective adjuvant was investigated for its direct impact on the pathogen and deposition of BCAs using electron microscopy and its compatibility with the BCAs and zucchini plant was evaluated to establish an integrated management of powdery mildew. Furthermore, effects of Si spray in accumulation of Si and K in the leaves were measured. Break-Thru® and Partner 650® improved the efficacy of silicate by 18–35%. The best adjuvant, Break-Thru®, caused a collapse and degeneration of the conidia and hyphae of the pathogen, restricted growth and spread of the powdery mildew colonies by binding its propagative structures, and improved deposition of BCAs on the leaf surface and the fungus. Break-Thru® was compatible with the plant and the BCAs at concentrations <0.4 ml l−1, and can be used with selected BCAs and SiO2 for an integrated management of powdery mildew. SiO2 applied as a foliar spray increased the level of Si in zucchini leaves, which may contribute to systemic resistance of the plant against the disease.

Accumulation of Weathered P,P′-DDE in Xylem Sap Of Grafted Watermelon

Movement of weathered p,p′-dichlorodiphenyldichloroethane (p,p′-DDE) from contaminated soil to the rhizosphere pore water to the xylem sap of grafted watermelon was studied under green house conditions. p,p′-DDE concentrations in pore water and xylem sap was compared in intact plants, homografted, and compatible heterografts of Cucurbita pepo spp. pepo and Citrullus lanatus plants.An average p,p′-DDE concentrations in pore water of contaminated soil ranged from 0.36 μg/L to 0.55 μg/L and there were no statistically significant among the cultivars. Conversely, the xylem sap p,p′-DDE concentration of heterografted watermelon having a zucchini rootstock and watermelon scion was 71 μg/L and it was greater than intact watermelon plants (0.49 μg/L) but less than that of intact plants of zucchini (141 μg/L). Homografting showed no effect on xylem sap p,p′-DDE concentrations of the identical cultivars. The bio-concentration factors (BCFs) which is an average p,p′-DDE concentration in xylem sap over average p,p′-DDE in pore water were 344, 325, 197, 1.28, and 0.89 for intact plant of zucchini, homografted zucchini, heterografted watermelon, homografted watermelon, and intact plant of watermelon, respectively. Xylem sap p,p′-DDE concentrations of the heterografted watermelon plants were clearly influenced by plant phylogeny and enhanced by the zucchini rootstock compared to intact watermelon plants.

Determination of acetamiprid residues in zucchini grown under greenhouse conditions: application to behavioral dynamics

A simple analytical method was developed for the determination of acetamiprid residues in zucchini and zucchini leaves grown under greenhouse conditions using liquid chromatography. Residues were confirmed via tandem mass spectrometry in positive-ion electrospray ionization mode. The calibration curves were linear with correlation coefficients in excess of 0.999. The limits of detection and limits of quantification were 0.01 and 0.03 µg/g and 0.02 and 0.06 µg/g, for the zucchini and zucchini leaves, respectively. For validation purposes, recoveries studies were carried out at low and high levels, yielding recovery rates ranged from 85.7 to 92.2% in zucchini and from 90.5 to 101.9% in zucchini leaves, with a relative standard deviation of <12%. The results demonstrated that the pattern of acetamiprid dissipation followed pseudo first-order kinetics with a half-life of 1.9 and 2.5 days, respectively. The residues in zucchini leaves were substantially higher than in the zucchini plant itself. No residues were detected at 7 days post-application. The results of this study suggest that acetamiprid is acceptable for application in/on zucchini under the recommended dosage conditions.

Alleviation of salt stress by arbuscular mycorrhizal in zucchini plants grown at low and high phosphorus concentration

With the aim of determining whether the arbuscular mycorrhizal (AM) inoculation would give an advantage to overcome salinity problems and if the phosphorus (P) concentration can profoundly influence zucchini (Cucurbita pepo L.) plant responses to AM, a greenhouse experiment was carried out with AM (+AM) and non-AM (−AM). Plants were grown in sand culture with two levels of salinity (1 and 35 mM NaCl, giving electrical conductivity values of 1.8 and 5.0 dS m−1) and P (0.3 and 1 mM P) concentrations. The percentages of marketable yield and shoot biomass reduction caused by salinity were significantly lower in the plants grown at 0.3 mM P, compared to those grown at 1 mM P. However, even at high P concentration, the absolute value of yield and shoot biomass of +AM zucchini plants grown under saline conditions was higher than those grown at low P concentration. The +AM plants under saline conditions had higher leaf chlorophyll content and relative water content than −AM. Mycorrhizal zucchini plants grown under saline conditions had a higher concentration of K and lower Na concentration in leaf tissue compared to −AM plants. The P content of zucchini leaf tissue was similar for +AM and −AM treatments at both low and high P concentrations in the saline nutrient solution. The beneficial effects of AM on zucchini plants could be due to an improvement in water and nutritional status (high K and low Na accumulation).