O uso de água salina na irrigação é muito comum em cultivos de melão em regiões semi-áridas, o que pode resultar na salinização do solo e redução de rendimento se o manejo da irrigação não for adequado. O presente trabalho teve como objetivo avaliar o crescimento e o acúmulo de N, P e K em plantas de melão (Cucumis melo, L.) irrigadas com água salina. Os tratamentos estudados resultaram da combinação de dois fatores: salinidade da água de irrigação (1,1; 2,5 e 4,5 dS m-1) e materiais de melão (híbrido Trusty e cultivar Orange Flesh). O delineamento estatístico adotado foi de blocos inteiramente casualizados com quatro repetições, com tratamentos arranjados em esquema fatorial 3 x 2. A época de coleta de plantas foi analisado como outro fator e os resultados interpretados por análise multivariada. As plantas amostradas foram fracionadas em folhas + ramos e frutos, determinaram-se as produções de matérias secas e os conteúdos de N, P e K nestes materiais. Os acúmulos dos nutrientes nos frutos e de fitomassa seca na planta diminuíram com o incremento da salinidade da água de irrigação. Os frutos exportaram, em média, 57,1%, 67,1% e 70,0% dos totais de N, P, K, absorvidos pela planta e alocados na parte aérea, mostrando, portanto, que foram o principal dreno para estes nutrientes na planta.
corn is a highly appreciated product by people in the Northeast, and is also used in the preparation of typical regional dishes. After the green ears are harvested, the husks are used as a feedstuff for cattle. The production of green ears is interesting for several reasons. The ears can be harvested in a very short time (70 to 75 days), and up to four annual crops can be obtained. If the grower does not intend to sell green ear corn, the dry grain can still be ABSTRACTCorn cultivation in the Northeast region of Brazil is characterized by a great diversity of production systems, ranging from large companies (modern cultivars and relatively high planting densities) to small farms (family agriculture, traditional cultivars, and low planting densities). In the present work we evaluated the effects of planting density (30; 40; 50; 60; or 70 thousand plants ha -1 -TPH) on green ear yield of cultivars Centralmex (traditional) and AG 510 (hybrid). Different densities were achieved by maintaining 1.0 m between rows and varying the spacing between pits, within the row. Cultivars and planting densities were combined in a factorial scheme, arranged in a random block design with four replicates and four 6 m long row plots. The number of green ears increased with density in both cultivars, but in a significantly more intense pace in cultivar AG 510. Cultivar AG-510 (14.9 t ha -1 on average, maximum yield at 58 TPH) yielded significantly more unhusked green ears than cultivar Centralmex (13.6 t ha -1 on average, maximum at 61 TPH). Marketable green ear yield increased with density in both cultivars, but more intensively in cultivar AG 510, which significantly out yielded cultivar Centralmex from 43 TPH ahead. The difference between cultivars at the planting density of 70 TPH was 14.4 t ha -1 . There was no response of cultivar Centralmex in number of marketable husked green ears, while cultivar AG 510 increased yield with planting density. The difference between both cultivars started being significant at 38 TPH. Husked ear length decreased linearly and similarly in both cultivars as planting density increased. Planting density did not influence plant and ear height, and cultivar Centralmex was superior in both characteristics at all planting densities. There was no effect of cultivars on stalk diameter and root system biomass. Both characteristics decreased linearly as planting density increased.
The sweetpotato (Ipomoea batatas L., Convolvulaceae family) originated in Latin America and is currently cultivated worldwide. The storage roots, rich in calories, have made this crop one of the main caloric sources for low-income populations, especially in developing countries. Brazil annually produces about 805,000 tons, with the Northeast region responsible for 34% of this production (Albuquerque et al. 2020). In October 2019, sweetpotato plants cv. Campina, from a field in the region of Touros, state of Rio Grande do Norte (RN), Brazil (5°12’31”S 35°34’42”W), presented deformed storage roots, with galls, typical of root-knot nematodes. The roots were sent to the Nematology Laboratory (LabNema) where 14,032 eggs and 3,312 second-stage juveniles (J2s) of Meloidogyne sp., in 10 g of roots, were recovered. The species of adults was identified through morphological, biochemical, and phylogenetic analysis. The perineal region of females (n = 10) presented an oval shape, with a high and semi-trapezoidal dorsal arch and streak-free perivulval region. The labial region of males (n=10) presented high and rounded head cap, labial region slightly set off from the body, without annulations. The morphological characters were compatible with the original description of Meloidogyne enterolobii (Yang and Eisenback 1983). The phenotype of esterase isoenzymes showed two major bands (VS1-S1) also characteristic of M. enterolobii (Esbenshade and Triantaphyllou 1985). Sequences of 18S rDNA (~1200bp) of individual females (Holterman et al. 2006) obtained from sweetpotatoes before (SPme1 and 2) and after inoculation (SPme3 and 6), and from guava, used as M. enterolobii species control, were submitted to Bayesian analysis. The sequences presented genetic diversity among them resulting from seven SNPs (Single Nucleotide Polymorphism) and 99.4 to 99.9% identity with M. enterolobii sequences deposited in the NCBI GenBank (accession numbers MW209034-MW209039). The pathogenicity test was carried out under greenhouse conditions, in which 3,000 eggs and J2s from the original population isolated of M. enterolobii were inoculated in sweetpotato seedlings cv. Campina (n = 6). After three months, the roots presented galls and deformations typical of root-knot nematodes, while non-inoculated plants did not present any symptoms. An average of 15,900 eggs and J2s of M. enterolobii (RF = 5.3) were recovered from the roots, proving that sweetpotatoes were a host of this species. Meloidogyne enterolobii is known to cause great damage to sweetpotato (Ye et al. 2020). In Brazil, Meloidogyne nematode had been reported once, isolated from a sweetpotato field in the Ceara state and the species suggested by the authors according to esterase electrophoresis was M. enterolobii. Nonetheless, the authors did not present taxonomic, isoenzyme phenotypes and molecular species identification integratively, nor included pathogenicity tests (Silva et al. 2016). Therefore, it is the first time that M. enterolobii, with reliable identification by different methods, including sequencing, was detected in commercial sweetpotato fields in the RN state and in Brazil. The local farmers reported that this nematode deforms the storage roots which make them useless for commercialization, resulting in minimal losses of 50% of production in the infested areas. Furthermore, as sweetpotatoes are vegetatively propagated, the spread of this nematode through planting material is favored. Considering the importance of this crop in Brazil, this report is essential for control measures of this pathogen to be taken in order to avoid its spread to other regions.
Tomato spotted wilt virus (TSWV, family Tospoviridae, genus Orthotospovirus) is a thrips-vectored pathogen that infects lettuce (Lactuca sativa) and many vegetable crops (Kuo et al. 2014, Hasegawa et al. 2022). Another thrips-borne pathogen of lettuce, impatiens necrotic spot virus (INSV, Tospoviridae, Orthotospovirus), was first reported in 2021 in Yuma, Arizona (Hasegawa et al. 2022). Symptoms of both viruses in lettuce are similar and include necrotic spotting, leaf chlorosis and plant stunting (Kuo et al. 2014). Beginning February through April of 2022, lettuce displaying symptoms of orthotospovirus infection was collected from romaine lettuce (var. longifolia) fields in three regions of Yuma County. A total of 96 plants were collected (5 from Tacna on 2/21, 5 from Wellton on 2/21, 15 from Wellton on 3/23, 30 from Tacna on 4/4, 20 from Wellton on 4/4, and 21 from Yuma Valley on 4/4). The area of the fields ranged from 10 to 18 acres, and the percent disease incidence ranged from 0.8% (Tacna on 4/4) to 2.75% (Tacna on 2/21). Thrips vector were present in all fields were symptomatic plants were observed. One leaf disk per plant (8 mm in diameter) was sampled with a cork borer and grounded individually with a micro pestle in a 1.7 ml microcentrifuge tube with 150 ul of Tri-reagent (Molecular Research Center). Total RNA was extracted from each sample using the Zymo Direct-zol-96 kit (Zymo Research). Samples were diluted with water to a ratio of 1:10 after RNA extraction. RT-qPCR was performed in 20 ul reactions with 5 ul of input RNA using the PCR Biosystems qPCRBIO Probe 1-Step Go No-ROX for the cDNA/qPCR master mix. RT-qPCR assays were carried out in multiplex reactions using primers specific for TSWV and INSV, in addition to a lettuce internal control gene (LOC111918243), along with negative controls. Primer and probe sequence details are reported in supplemental Table 1. We used a cycle threshold (ct) < 40 to indicate a positive result for both INSV and TSWV (Chen et al. 2013; Boonham et al. 2002). RT-qPCR successfully amplified INSV in 90 out of 96 samples and TSWV in 8 out of 96 samples. These 8 samples tested positive for both TSWV and INSV, showing that INSV and TSWV co-infected lettuce plants. Thus overall, ∼ 95% of symptomatic plants were infected with INSV alone, and ∼ 8% were co-infected with TSWV and INSV. Amplicons of 4 samples testing positive for TSWV were sent for Sanger sequencing (Eurofins Genomics, Louisville, KY). All were identified as TSWV. One amplicon with TSWV was sequenced for INSV and double infection was confirmed. BLAST results from the NCBI nt database show 100% (138 bp) identity to TWSV (MW519211) for the 4 TWSV amplicons and 99.22% (137 bp) identity to INSV (KX790323) for the INSV amplicon. Sanger sequence data are in the GenBank (accession: OQ685940-OQ685944). Based on RT-qPCR results, all TSWV infected plants were also infected with INSV. INSV may have been introduced to Yuma by infected plants or thrips from lettuce transplants produced in California (Hasegawa et al. 2022). TSWV could have been introduced similarly. To our knowledge, this is the first report of TSWV infecting lettuce in Yuma and the first report of INSV and TSWV co-infecting lettuce. TSWV and INSV infections have remained low since their discovery in Yuma, in part due to effective cultural and chemical management by lettuce growers (Palumbo, 2022). However, an increase in disease incidence and severity in the future could have a significant negative impact on production of romaine lettuce in the region.
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