The rational use of water is essentual as it is a finite resource. Consequerntly, studies of methids that minimize water use water are essential. As a result, agricultural hydrogels have been extensively tested in as a means of promoting agriculture improvements because of their water- and nutriente-retention characteristics. However, even though hydrogels are used in several sectors of Brazilian agriculture, there are still very few studies on their applications, the best methods and the quantities to be used. Consequently, there is a need for research into the applicability of this technology in Brazil, so that future research needs can be identified and appropriate decisions made at the production level. Therefore, the aim of this study was to collate currently available information on the applicability of agricultural hydrogels in Brazilian agriculture. Over the last decade, forestry is the sector in Brazil that has most studied and used hydrogels, but others such as fruit- and coffeegrowing have also been involved. The method of applying the polymer in granules directly mixed-in with growth substrates is the most used in the production of seedlings. However, use of hydrated gel at planting sites has also been explored. While synthetic hydrogels are most commonly used, those made of natural materials have great potential due to the low preparation costs and their in-soil biodegradability. The quantities of hydrogel used vary according to the target species, application method and objective.

Produzir mudas de pimentão com qualidade é essencial à obtenção de plantas vigorosas e produtivas em campo

La utilización de extractos vegetales como insecticidas naturales es una alternativa eficiente y ecológicamente viable para el uso directo en el control de plagas. En el estudio se evaluó el efecto de diferentes concentraciones de resina de Jatropha curcas en el control de larvas de Hypsipyla grandella Zéller, para el efecto en un Diseño Completamente al Azar (DCA), en esquema de parcelas subdivididas, se evaluaron cinco tratamientos, en tres repeticiones y 10 discos foliares de S. macrophylla por unidad experimental. Las parcelas principales consistieron en cinco concentraciones (%) de resina de J. curcas: T1:0; T2: 10; T3: 20; T4: 30; y T5: 40 y las subparcelas en los tiempos de evaluación (horas): 6, 12, 18 y 24 en el transcurso del día. Como variables medidas se incluyeron el consumo del disco foliares-CDF (%), el incremento de consumo foliar-ICF (%), la sobrevivencia-SL (%), la mortandad – ML (%), el número de orificios foliares-NOF y actividad larval-AL (%). La resina de J. curcas en concentración de 40% ocasiona en larvas de H. grandella una mortalidad de 67% y una actividad larval < 30%). Los resultados indican que las concentraciones de extracto de J. curcas ocasionaron efectos significativos en todas las variables evaluadas, no obstante, las concentraciones menores fueron menos eficientes en el control de larvas. Se concluye que la resina de J. curcas es un bioinsecticida potencial en el control de larvas de H. grandella presentando los mejores resultados en concentraciones > 30%.

Adenium obesum (Forssk.) Roem. & Schult., widely known as desert rose, has attracted interest for its esthetic characteristics, which are influenced by the process of seedling production. Using two consecutive experiments installed fully at random, the study aimed at assessing the use of different substrates and hydrogel to produce desert rose seedlings in a protected environment. First, eleven substrates were tested, prepared as follows: OrganoAmazon®; PuroHumus®; soil; rice husk in natura; carbonized rice husk, sawdust and cattle manure. Then, three substrates were tested (S1 - OrganoAmazon® + PuroHumus®; S2 - OrganoAmazon® + PuroHumus® + rice husk in natura and S3 - OrganoAmazon® + PuroHumus® + carbonized rice husk) associated to four hydrogel levels: 0 (daily irrigation), 1, 2 and 3 g L−1 (irrigated on alternate days). Growth variables and quality index of seedlings were assessed. Six substrates (all of them without addition of sawdust and where used in mix) were grouped as those the promoted appropriate growth of seedlings, with height, number of leaves, collar diameter, root length and aerial part biomass superior to 6.5 cm; 13; 12 mm; 7.5 cm and 0.45 g, respectively. The substrate composed of OrganoAmazon® + PuroHumus® (1:1 v/v), when irrigated daily, was the one that favored most the production of quality seedlings. The use of hydrogel in substrates with shifts of irrigation on alternate days did not favor the production of desert rose seedlings.

Sugar apple (Annona squamosa L.) is one of the most widely grown member of the Annonaceae family in several regions, but there is still a lack of agronomic data regarding the management of its initial growth stages under Cerrado conditions. The aim of the present study was to evaluate the production of Annona squamosa L. seedlings under different environmental conditions achieved by using shade nets (E1: ChromatiNet® Silver 50%; E2: ChromatiNet® red 50%; E3: ChromatiNet® red 35%; E4: ChromatiNet® Silver 35%) in combination with four different substrates (S1: soil + sand + chicken manure; S2: soil + sand + cattle manure; S3: soil + sand + cattle manure + chicken manure; S4: soil + sand + sheep manure). An experiment was set up using a completely randomized design with treatments in a split-plot arrangement, with four replicates and ten plants per experimental unit. Seedling growth parameters and quality indices were evaluated. The tested environments had higher local temperatures relative to the external environment, which had a negative effect on plant growth. Environment E2 resulted in the highest plant height and dry weight, but led to uneven growth among the evaluated plant parts. The substrate with sheep manure (S4) did not benefit seedling production. The best results for seedling growth and quality were obtained with substrates S2 (soil + sand + cattle manure) and S3 (soil + sand + cattle manure + chicken manure), which are therefore promising for Annona squamosa L. seedling production in the Roraima Cerrado.

Camu-camu (Myrciaria dubia), a fruit from the Amazon region, has received attention due to its high content of antioxidant compounds such as ascorbic acid and polyphenols. This study’s objective was to select camu-camu clones according to their morphological characteristics using multivariate analyses. We evaluated 56 camu-camu clones distributed in three blocks with two plants per experimental plot. The variables measured were plant height (H), number of basal branches (NBB), number of terminal buds (NTB), basal stem diameter (BSD), chlorophylls a (Chl a) and b (Chl b), and total chlorophyll (Chl a + b). Principal component (PCA) and multivariate clustering analyses were performed using the average linkage mean and Mahalanobis distance algorithms. After 24 months, results showed that the characteristic that least contributed to clone selection was NBB. The plant height (H), number of terminal buds (NTB), basal stem diameter (BSD), chlorophylls a (Chl a) and b (Chl b), and total chlorophyll (Chl a + b) had the most positive contribution towards the initial selection of camu-camu clones at two years of age. The 22 camu-camu clones showed the highest rate of vegetative development or vegetative quality index (VQI) in the transitional savanna/forest area of the northern Amazon, Brazil, after two years of transplanting.