Evaluation of the agronomic factors and their effects on the yield and bromatological composition of Morus alba Linn.

 


Giraldo Martín Martín

Estación Experimental de Pastos y Forrajes Indio Hatuey Central España Republicana 44280, Matanzas, Cuba

 

ABSTRACT
This work was aimed at evaluating the agronomic factors and their effects on the yield and bromatological composition of the biomass of mulberry, as well as determining, through regression equations, the relations between the yield in dry matter of mulberry and the total green weight of plants. An economic appraisal was made of this forage, in order to evaluate the feasibility of its utilization as substitute of the commercial concentrate feed used in the enhanced dairy farms of the agriculture system in our country. The experimental essays were conducted at the Pastures and Forages Research Station, located between 22º 48’ and 7’’ North latitude and 81º and 2 ‘ West longitude, at 19,01 m.a.s.l., in the Perico municipality, Matanzas province, Cuba. For setting the experiment a randomized block design with factorial arrangement was used; three factors were included (variety, fertilization and cutting frequency), which originated a total of 36 treatments replicated four times, that is, 144 plots. The studied varieties were: Indonesia, Cubana, Acorazonada and Tigreada. Three fertilization levels were used with nitrogen-based chicken dung (100, 300 and 500 kg N/ha/year) and three cutting frequencies (60, 90 and 120 days). Due to the seasonality of forage production in the tropics, season was included as an additional factor. The dry matter yields of leaves, fresh stems, edible biomass, woody stems and total biomass were used as agronomic variables. As indicators of the bromatological composition the percentages of dry matter, crude fiber, crude protein, calcium, phosphorus, potassium and ash were studied, in the leaves and fresh stems. In addition, the crude protein yield was determined in the leaves, fresh stems and edible biomass. For processing the experimental results, the statistical pack SAS (Statistical Analysis System), version 8.0, and the statistical pack SPSS, version 10.0, were used. The experimental results showed that the dry matter yield of the total biomass and its components was influenced mainly by the cutting frequency and the season. The highest dry matter yields of leaves, edible biomass and total biomass were obtained with the cutting frequency of 60 days in the rainy season in the varieties Indonesia, Acorazonada and Tigreada, and with the 90-day frequency in the rainy season in the Indonesia variety. The increase of fertilization stimulated the dry matter production of leaves, fresh stems, edible biomass and total biomass, but with a decrease of the efficiency in the utilization of the nitrogen present in the poultry dung. The factors cutting frequency and season had significant effects on the crude fiber and crude protein contents in the leaves and fresh stems. The calcium, potassium and ash contents found in mulberry were high and higher than those of conventional forages in the tropics. The crude protein yields of leaves, fresh stems and edible biomass in the rainy season, were higher for the cutting frequency of 60 days. The linear regression and quadratic equations obtained for the set of the cutting frequencies, indicate that the total green weight of mulberry plants is an estimation variable to determine the dry matter yields of leaves, edible biomass and total biomass of mulberry, under similar conditions as the ones used in this essay. The economic considerations made in this work proved the feasibility of substituting the commercial concentrate feed by mulberry forage as supplement for the production of cattle milk. Taking the results into consideration it is recommended to use, in the rainy season, the varieties Indonesia, Acorazonada and Tigreada for the production of high quality forage with a cutting frequency of 60 days, and in the dry season the variety Indonesia with cuttings every 90 days, to optimize the utilization and conservation of the edible biomass of this plant. Likewise it is suggested: to widen the studies about the use of biofertilizers, chemical and organic fertilizers alone or combined, in order to achieve a more efficient use of nutrients; to evaluate the feasibility of performing irrigation at times of intense droughts; to validate in commercial plantations the regression equations obtained to estimate the yields of leaves, edible biomass and total biomass of mulberry; and to evaluate the productive potentialities and the economic feasibility of using this plant at commercial scale.