Avaliação de clones de palma forrageira no Agreste e Sertão de Pernambuco

• Autor(a) principal: FERRAZ, André Pereira Freire
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRPE
• Texto Completo: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/8103
• topic: Palma forrageira; Cochonilha do carmim; Cochonilha de escama; Dactylopius opuntiae; Diaspis echinocacti; Análise multivariada; CIENCIAS AGRARIAS::ZOOTECNIA

Forage cactus is an important forage resource for the Brazilian semi-arid region. However, the occurrence of carmine cochineal (Dactylopius opuntiae) and armored scales (Diaspis echinocacti) has been putting plant production at risk. The objective of this study was to evaluate the morphological characteristics, quality and forage production and the incidence of carmine cochineal and armored scales in forage cactus clones cultivated in ‘São Bento do Una’ and ‘Sertânia’, Pernambuco State, besides the genetic diversity among the clones. Ten clones were evaluated: ‘IPA 20,’ ‘F8,’ ‘F21,’ ‘Miúda,’ ‘IPA Sertânia’, ‘Orelha de elefante mexicana,’ ‘IPA-100421 Sel. 21-6’ (6), ‘IPA-100418 Sel. 21-7’ (7), ‘IPA-100419 Sel. 21-13’ (13) e ‘IPA-100420 Sel. 21-21’ (21). The genotypes were randomized in blocks with three replications, and the harvests were carried out in 2015 and 2017. The plants were evaluated for the width and plant height; number of cladodes; length, width and cladode thickness; cladode area index, light interception, forage production, water use efficiency, plant stand and bromatological characters. The incidence of the cochineal insects was evaluated from scales varying from 0 to 5, where the lowest score (0) represented absence of the insect on plant, and in the largest score (5) insects were present in all cladodes and in high infestation (>75%). The data were submitted to joint analysis of variance and the means of the genotypes compared by the Scott-Knott test (p≤0.05). The genetic divergence between the genotypes in the different environments was evaluated through the Tocher and UPGMA clustering methods. As a measure of dissimilarity was used the generalized Mahalanobis distance (D2) and estimated the relative importance of characters to genetic diversity. Clones 6, 7, 13 and 21, in general, presented higher height and width of plants, besides being among those that produced more cladodes per plant. The dry matter production (tons ha-1 2 years-1) decreased in both cultivation sites, from 2015 to 2017 (p <0.05), and in São Bento do Una, forage production was higher and varied from 28 to 14 tons MS ha-1 2 years-1 in 2015 and 2017, respectively. However, regardless of locations and harvests, genotypes 6, 7, 13, 21 and ‘Orelha de elefante mexicana’ were the most productive (18.82 ± 12.19 tons DM ha-1 2 years-1). Genotypes 6, 13 and 21 also showed higher water use efficiency (p<0.05) (26.08 ± 17.34 kg DM ha-1 mm-1). The plant stand did not vary (p<0.05) in the different environments in the harvest of 2015. On the other hand, it decreased in the second harvest (2017), and ‘Sertânia’ presented the lowest number of live plants (66% of the initial stand). In ‘Sertânia’, clone IPA 20 was the one that presented the smallest stand (55% of the initial live plants). In ‘São Bento do Una’, clone 7 presented the lowest survival performance (57%). In general, plants of the Nopalea genus presented higher dry matter content. All clones showed high organic matter digestibility (> 800 g kg-1). In the harvest of year 2015, ‘Sertânia’ was the place most attacked by carmine cochineal (1,00 ± 0,31) in relation to ‘São Bento do Una’ (0,57 ± 0,21). In the latter place, attacks by armored scales were more severe (1.93 ± 0.23). The D2 estimate indicated that the pairs formed by clones 21 and ‘Orelha de elefante mexicana’ were the most genetically distant, and the clones F21 and F8 were the most similar. Three divergent groups were identified in both clustering methods (Tocher and UPGMA). Genotypes 6, 7, 13, 21 and ‘Orelha de elefante mexicana’ showed higher productive performance in both environments. Genotypes 13 and 21 showed greater potential for use in sites where both cochineal insects occur. In addition, ‘Orelha de elefante mexicana’, ‘IPA Sertânia’ and ‘Miúda’ cultivars can be grown in places where carmine cochineal occurs. It is recommended to avoid planting the ‘IPA 20’, ‘F21’ and ‘F8’ clones, as they can be attacked by both cochineal insects. The cladode width, total number of cladodes, dry matter content, dry mass production and number of fifth and third order cladodes were the main contributors to the genetic divergence found.