Estimation the Yield and Intercropping Indices of Garlic (Allium sativum L.) and Peas (Pisum sativum L.) in two Regions of Sari and Gonbad Kavoos

In intercropping systems, inputs in a unit area have been reduced but use of available resources is optimized, leading to increased production and promotion of evaluation indices. In a study on maize and peanut intercropping, the highest index of land equivalent ratio (LER=1.04) was obtained in 100% corn + 100% peanut. In addition, barley and peas as well as garlic and chickpea intercropping, improved the LER and the other intercropping indices. Therefore, the main objective of this research was the estimation of the yield and intercropping indices of garlic (Allium sativum L.) and peas (Pisum sativum L.) in two regions of Sari and Gonbad Kavoos.

The present research was conducted at research farms of Gonbad Kavoos University and Sari region during 2013-2014. The experiment was arranged based on randomized complete block design with three replications. Treatments were nine levels including sole cropping of garlic and pea, beside replacement series of 25:75, 50:50 and 75%:25% pea: garlic as well as additive series of 25, 50, 75 and 100% pea +100% garlic. Plot size was 1.8 × 6m with six rows of cultivation. Plant densities in the control treatment were the same for both garlic and peas, with a 30 × 10 cm square and rectangular plant arrangement with six lines of six meters long and 360 plants per plot. In the incremental mix of 25% pea + 100% garlic, 50% pea + 100% garlic, 75% pea + 100% and 100% pea + 100% garlic 90, 180, 270 and 360 plants of peas were added to each plot of garlic, respectively.

The results showed that the highest garlic yield (9800 kg.ha-1) was obtained in pure cropping in Sari region, which increased 14% as compared to the Gonbad Kavoos region. The yield of pods (1060 kg.ha-1) and seed (348.3 kg.ha-1) decreased (up to 64 and 61%, respectively) in pure cropping of peas in the Gonbad Kavoos region. In additive series, LER and relative crowding coefficient in100% of garlic + 100% peas was 1.33 and 1.49 as well as 1.1 and 2.54 in Sari and Gonbad Kavoos, respectively. Actual yield loss (AYL=-0.15 and -0.20) were observed only in Sari and in additive series of 75% peas + 100% garlic and 100% of peas + 100% garlic, respectively. In contrast, the intercropping advantage (0.38) was observed in Sari where the 25% of peas intercropped with 75% of garlic, increasing up to 15% as compared to the Gonbad Kavoos region. Furthermore, partial competitive ratio (CRa) for pea and garlic was affected by different planting arrangements. The highest CR value for garlic (1.55) was recorded when 25% pea was added to 100% garlic. The higher root system and leaf area of pea helps to its advantage in intercropping system. The partial advantage of intercropping for garlic was affected by planting arrangement. The maximum partial advantage was obtained in replacement series of 755 garlic +25% pea.

In general, results of the present research clearly showed that intercropping of garlic and peas improved yield performance and intercropping evaluation indices. In additive series, a mixture of 100% pea + 100% garlic with relative crowding coefficient of 5.17 was the best combination of intercropping in terms of yield improvement in both regions. The presence of garlic in the mixture, particularly in the Gonbad Kavoos region, dramatically reduced the adverse effect of cold temperature on seed yield of peas and prevented the severe reduction of yield. Therefore, in each region where it is possible to cultivate these two plants, it is recommended that garlic considered as the main plant and peas with a density of 75% or more could add to the mixture.

Acknowledgements

We are grateful to the University of Gonbad Kavoos for its contribution to the implementation of the project as well as Sari Agricultural Science