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Evaluation of allelopathic effects of chickpea root extracts on germination and early growth of sorghum (Sorghum halepense), soybean (Glycine max L.) and sunflower (Helianthus annus)

Mohammad Reza Chaichi and Leila Edalati-Fard

Agronomy Department, College of Agriculture, University of Tehran
E mail edalatyfard@yahoo.com

Abstract

The allelopathic effects of chickpea root extracts were studied on germination and early growth of crops in rotation: Five accessions of chickpea were sown in pots and were followed by three crops (sorghum, soybean and sunflower).Crops were planted in three sowing intervals (immediately after physiological ripening of chickpea, two weeks later and four weeks later). Experimental treatments were arranged as split-split plot and were compared in a completely randomized block design with three replications. Seed germination rate, germination percent, plant height, shoot dry weight and shoot/root ratio of crops were affected by different treatments. Seed germination rate of crops after chickpea line 5436 was significantly reduced after four weeks. Seed germination percentage increased as the crops were sown two weeks after chickpea physiological ripening. The crop height followed an increasing trend as they were sown later after physiological ripening of chickpea lines. The root extracts of line 4488 significantly reduced soybean biomass production. However, under the same conditions it enhanced biomass production of sorghum. The severity of chickpea root extracts inhibitory effects on crops was dependent on chickpea cultivar as well as the genetic characteristics of crops in rotation. Deferment in sowing date of crops from harvest time of chickpea decreased the deleterious effects of chickpea root extracts on subsequent crops.

Media Summary

Chickpea root extracts can reduce growth of sorghum, soybean and sunflower crops. Delayed sowing of other subsequent crops after chickpea harvest is recommended.

Keywords

chickpea, allelopathy, rotation, germination, early growth.

Introduction

Statements as early as 300 years BC point to the phenomenon that many crop plants, including chickpea (Cicer arietinum) and barley (Hordeum vulgare), inhibit the growth of weeds and crop plants other than barley (Rice 1984). In Iran chickpea is sown in winter (October & November) and harvested in spring. Sorghum (Sorghum halepense), soybean (Glycine max L.) and sunflower (Helianthus annus) can be planted in summer. Evaluation of allelopathic effects of chickpea root extracts on germination and early growth of these plants were studied.

Materials and Methods

The experiment was carried out at green house of agriculture, Tehran University, Iran. Two lines of chickpea (“kaka” and “pirouz”) were sown on soil texture loam clay sandy. Five seeds were sown in a pot and after establishment reduced to two plants. As a control, chickpea was not planted until effects of chickpea on other plants were shown. Crops were planted in three sowing intervals; immediately after physiological ripening of chickpea (0 week); two week after physiological ripening of chickpea (2 week); four week after physiological ripening of chickpea (4 week).

Then after physiological ripening of chickpea stems were cut and harvested. Then crops were planted at the pots that have chickpea roots. Growth parameters such as seed germination rate, germination percent, plant height, shoot dry weight and shoot/root ratio were measured. Experimental treatments were arranged as split-split plot and were compared in a Completely Randomized Block Design with triple replications.

Results and Discussion

Seed germination rate, germination percent, plant height, shoot dry weight and shoot/root ratio of crops were affected by different treatments. Seed germination rate of crops after chickpea line “pirouz” was significantly reduced after four weeks.

Seed germination percentage increased as the crops were sown two weeks after chickpea physiological ripening.

The crop height followed an increasing trend as they were sown later after physiological ripening of chickpea lines.The root extracts of line 4488 significantly reduced soybean biomass production.

However, under the same conditions it enhanced biomass production of sorghum. The severity of chickpea root extracts inhibitory effects on crops was dependent on chickpea cultivar as well as the genetic characteristics of crops in rotation. Deferment in sowing date of crops from harvest time of chickpea decreased the deleterious effects of chickpea root extracts on subsequent crops.

References

1-Rice, E. L. (1984). Allelopathy, Second Edition edition. Academic Press, Inc., Orlando.

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