Características agronômicas e químicas das variedades de cana-de-açúcar RB83-5486 e RB86-7515 sob irrigação e sequeiro

Abstract

R ESU M OObjetivou-se, neste trabalho, avaliar as características agronômicas e a composição química de variedades de cana-de-açúcar sob irrigação e sequeiro colhidas em final de safra. O delineamento experimental foi bloco ao acaso, com seis repetições, duas variedades (RB83-5486 e RB86-7515), em dois ambientes: irrigado e sequeiro. As produções de colmo e matéria seca foram favorecidas pela irrigação, com destaque para a RB86-7515. Maiores teores de proteína bruta, fibra em detergente ácido, celulose e menores teores de matéria seca, Brix, carboidratos não fibrosos (CNF) e digestibilidade in vitro da matéria seca (DIVMS) foram registrados nas variedades sob irrigação. A fibra em detergente neutro (FDN) e a relação FDN por Brix foram mais elevadas em condições irrigadas e a RB86-7515 apresentou maiores valores. A lignina foi maior na RB86-7515 irrigada. A RB83-5486 apresentou Brix e CNF mais elevados e melhor DIVMS que a RB86-7515. Maior potencial produtivo foi expresso em condições irrigadas, destacando-se a RB86-7515 enquanto a irrigação alterou a composição química, afetando negativamente o valor nutritivo das variedades; já a RB83-5486 apresentou melhor perfil nutricional. Palavras-chave: produção, teor de sólidos solúveis, valor nutritivoAgronomic and chemical characteristics of sugarcane varieties under irrigated and rainfed conditions A B ST R A C T The study aimed to evaluate the agronomic characteristics and chemical composition of sugarcane varieties, harvested at the end of the dry season, under irrigated and rainfed conditions. The experimental design was in a completely randomized blocks with six replications. Two varieties (RB83-5486 and RB86-7515) under irrigated and rainfed conditions were studied. The stalk and dry matter yield were improved by irrigation, especially in case of RB86-7515. Higher contents of crude protein, acid detergent fiber, cellulose and lower contents of dry matter, Brix, non-fiber carbohydrates (NFC) and in vitro dry matter digestibility (IVDMD) were obtained in the varieties under irrigation. The neutral detergent fiber (NDF) and NDF/brix were higher in irrigated conditions, variety RB86-7515 showing higher values. The lignin content was higher in the RB86-7515 under irrigated conditions. The RB83-5486 presented a better content of Brix, NFC and IVDMD than the RB86-7515. High productive potential was expressed under irrigated conditions, with emphasis on the RB86-7515. Irrigation influenced the chemical composition, negatively affecting the nutritional value of varieties. The RB83-5486 showed a better nutritional profile to be used as forage.

Intensity and duration of water deficit on the pathosystem sugarcane x Meloidogyne incognita

“…For Gonçalves (2008), sugarcane stem diameter is affected negatively by water deficiency in the initial phase of development. Macêdo et al (2012), studying the varieties RB835486 and RB867515 under different water regimes, observed that stem diameter varied according to the environment and the variety; also, it was found that the highest productive potential of the varieties was expressed in irrigated conditions.…”

Yield and technological performance of sugarcane cultivars grown under Af climate conditions

“…The NMP of sugarcane crops grown under the Aw and Am climate conditions ranged from 58.8 to 136.9 t ha -1 and 116.79 to 192.91 t ha -1 , respectively (Capone, Lui, Silva, Dias, & Melo, 2011;Oliveira et al, 2011). Macêdo et al (2012) evaluated two sugarcane cultivars in a Cwa climate under irrigated and rainfed conditions during the drought period, where the highest NMP (103.0 t ha -1 ) was observed in the irrigated cultivation. In the same study, the RB83-5486 cultivar had an NMP of 84.0 t ha -1 under irrigated conditions (Macêdo et al, 2012), while in the present study, its NMP was 250.16 t ha -1 .…”

“…Studies concerning the yield and technological attributes of sugarcane have been conducted in different climates, including As (Abreu, Silva, Teodoro, Holanda, & Sampaio, 2013), Aw (Cruz et al, 2010;Rhein et al, 2016), Awi (Caione et al, 2011), Cfa (Schwerz et al, 2017), and Cwa (Macêdo et al, 2012). However, information regarding the behavior of the sugarcane plant under Af climate conditions, which is characterized by abundant rainfall throughout the year and no dry season, is still required.…”

Stalk yield of sugarcane cultivars under different water regimes by subsurface drip irrigation

“…Studies conducted in different production environments have demonstrated increment in the stalk yield of sugarcane genotypes in response to irrigation (Carvalho et al, 2009;Gava et al, 2011;Oliveira et al, 2011;Macêdo et al, 2012;Silva et al, 2014). However, for the genotype-environment interaction, it is crucial to conduct tests aiming at the expression of the productive potential of the sugarcane cultivars in different water regimes and production environments (Silva et al, 2008).…”