عنوان مقاله [English]
Forage quality is limited in many forage production systems in developing countries, specifically in arid and semiarid conditions. Mixing Persian clover as a forage legume with cereals such as barley has been proposed as a way of increasing forage quantity and quality. Barley (Hordeum vulgare L.) is an annual cereal which can grow in marginal area, suppress weed pressure and provide high forage yield but protein content of the forage is low. Intercropping cereals and legumes have been suggested to increase forage nutrient .stated that barley intercropped with Berseem clover (Trifolium alexandrinum L.) compared with oat or triticale (Tritico×secale rimpaui Wittm.) produced higher protein in forage production. In addition, Lithourgidis et al. (2006) has been reported that vetch (Vicia sativa L.) intercropped with oat produced higher total protein compared with a sole stand of vetch. Carr et al. (2004) demonstrated that barley forage compared with oat (Avena sativa L.) had higher dry matter digestibility (DMD), lower acid detergent fiber (ADF), and higher crude protein (CP). In current study we compared a wide range of cropping rate and pattern to determine the best forage quality in mixture of barley and Persian clover in a low-input system.
Materials and methods
In order to find the optimum cropping rate and pattern in a mixture of barley and Persian clover an experiment was conducted in a split plot layout based on randomized complete block design with three replications at Research Farm of College of Agriculture, Ferdowsi University of Mashhad in 2013-14. The pattern of sowing considered in five levels (row intercropping 1:1, sowing one row barley one row clover (M1), row intercropping 2:2, sowing two row barley two row clover (M2), strip intercropping 3:3, sowing three row barley three row clover (M3), strip intercropping 4:4, sowing four row barley four row clover (M4) and mixed cropping barley and clover (M5)) which allocated as main plots and the cropping rate in five levels (additive mixture of barley %100: %50 clover (R5), additive mixture of barley %100: %25 clover (R4), replacement mixture of barley %50: %50 clover (R3), with pure barley (R2)and pure clover (R1)) proposed as subplots. Barley (Watan local variety originated from Herat, Afghanistan) and Persian clover (Trifolium respinatum L.) seed rates were considered 120 kg.ha-1 and 40 kg.ha-1, respectively. Sowing date was on October 23. Barley was harvested in heading stage and clover in completed flowering stage. Two random samples (0.5-1 kg) were chose in each plot to determine forage fresh yield and quality characteristics. Samples were dried at 75ºC for 72 h, then milled and determined percentage of forage dry matter. The forage quality characteristics examined were dry matter digestibility (DMD), organic matter digestibility (OMD), digestive value (D-value), crude protein (CP), protein yield (PY), neutral detergent fiber (NDF) and acid detergent fiber (ADF). The pepsin-cellulase In vitro two step method was used for determine DMD, OMD and D-value. Crud protein; NDF and ADF contents were determine based on Nelson et al. (1973) and Goering and Van Soest (1970) methods, respectively. Analysis of variance (ANOVA) and lest significant different test (LSD) were performed using SAS version 9.3 (SAS Institute Inc., Cary, NC, USA).
Results and Discussion
Results showed that the effect of cropping rate and pattern on DMD, OMD, D-value and protein yield (PY) were significant (p<0.01). The highest levels of DMD, OMD and D-value were obtained in M1 sowing pattern and R1 pure clover, respectively .The effect of sowing pattern on CP, NDF and ADF contents were not significant. The highest CP content was shown in pure clover (16.3 %) and the highest PY were obtained in pure barley (1962.2 kg.ha-1) and mixed cropping (1584.4 kg.ha-1). So producing high DMD, OMD, D-value and CP in clover and PY in barley alone is not sufficient but must also consider the stability of the system that it is implemented in mixed cultures.