Evaluating yield and land equivalent ratio in mixcropping of balangu (Lallemantia royleana Benth.) and chickpea (Cicer arietinum L.) affected by weed competition

Intercropping is considered to be important for a lot of reasons like optimizing water and soil resource uses, increasing water use efficiency, increasing pest, diseases and weed control efficiency, decrease pesticide application, increasing total production and land equivalent ratio and sustainability in agroecosystems. Production of medicinal plants requires sustainable and healthy methods like intercropping for increasing quantity and quality of medicinal plants and intercropping is one of the methods has special attention for this approach. Intercropping would be more successful when one of the intercropping components is legume, because of their nitrogen fixation ability and compatability to different planting patterns in mixcropping systems. Chickpea and balangu planting date is close together, with these abilities of legumes and planting dates it seems that their intercropping is an ideal purpose for medicinal production. It is possible that chickpea nitrogen fixation is useful for balangu growth and allelopathic effects of balangu with planting patterns with increasing canopy covering on the ground and shading on weed seedling would be helpful to improve quality and quantity in this intercropping. The objective of this study was to evaluate the chickpea and balangu intercropping possibility, land equivalent ratio and effect of weed control in this intercropping pattern.
 

The experiment was arranged as a factorial based on randomized complete blocks design with three replications and performed at research farm of faculty of Agriculture, Ferdowsi University of Mashhad, Iran, during 2015-16 growing season. Treatments considered six planting (Chickpea/Balangu) ratio: (100/0, 100/25, 100/50, 100/75, 100/100, 0/100) and two weeding time (50 and 70 days after planting). Chickpea and balangu were planted at the same time (March 11th) in the way that Balangu is planted on the top of the rows with high density and chickpea is planted on the sideways of rows in recommended density (40 plant/m-2). When Balangu is emerged, they were thinned to its recommended density (40 plantm-2). Because of good precipitation during the growing season, one time irrigation was applied at the beginning of chickpea poding and balangu seed ripening. To determine the effect of treatments, chickpea and balangu biomass and seed yield were determined at the end of the season. To compare the performance of intercropping, land equivalent ratio (LER) was used, according to below equation: 
 
RYa: relative intercropped yield out of monocropped plant a yield Ryb: relative intercropped yield out of monocropped plant b. Yab: yield of plant a intercropped with plant b, Yba: yield of plant b intercropped with plant a, Yaa: yield of plant a monocropped, Ybb: yield of plant b monocropped. The data statistical analysis and draw the figures were performed by Mini Tab Ver 17 and Excel 2013. Means were also compared by Fisher test at 5% probability level.
 
 

Results indicated that chickpea biomass and seed yield decreased as 24 and 55 percent respectively in 70 days after planting weeding time. However, biomass and seed yield were increased 5.7 and 20.4 percent respectively in balangu. By increasing balangu density, balangu seed yield increased but chickpea seed yield decreased significantly. The highest seed yield and biomass in both crops is observed in their monocropping and 50 days after planting weeding time. When weeds were left longer (70 days after planting) to compete with the crops, yield was decreased. Results showed that land equivalent ratio (LER) in 100/25 (chickpea/ balangu) plant ratio were the highest (1.52) and is useful and economic in chickpea and balangu intercropping.
 

Based on the results, by increasing the balangu density, biomass and seed yield of chickpea was significantly decreased even at the lowest balangu density. However increasing balangu density, increased balangu yield. It seems balangu is competing with chickpea strongly. However balangu planting at 10, 20 and 30 plant m-2 density with 40 plant m-2 chickpea increased land equivalent ratio by more than 1, especially in the lowest balangu density (10 plant m-2) when weeding were did at the 70 days after planting. Generally intercropping of balangu and chickpea in Mashhad and the same climate condition recommended in 100/25 (chickpea/ balangu) plant ratio (40 chickpea plant m-2 + 10 balangu plant m-2) and it would be useful and economic.