Improvement of Faba Bean Yield Using Rhizobium/Agrobacterium Inoculant in Low-Fertility Sandy Soil

Sameh Youseif,Saleh Saleh,Fayrouz Abd El-Megeed

doi:10.3390/agronomy7010002

Abstract

Soil fertility is one of the major limiting factors for crop’s productivity in Egypt and the world in general. Biological nitrogen fixation (BNF) has a great importance as a non-polluting and a cost-effective way to improve soil fertility through supplying N to different agricultural systems. Faba bean (Vicia faba L.) is one of the most efficient nitrogen-fixing legumes that can meet all of their N needs through BNF. Therefore, understanding the impact of rhizobial inoculation and contrasting soil rhizobia on nodulation and N2 fixation in faba bean is crucial to optimize the crop yield, particularly under low fertility soil conditions. This study investigated the symbiotic effectiveness of 17 Rhizobium/Agrobacterium strains previously isolated from different Egyptian governorates in improving the nodulation and N2 fixation in faba bean cv. Giza 843 under controlled greenhouse conditions. Five strains that had a high nitrogen-fixing capacity under greenhouse conditions were subsequently tested in field trials as faba bean inoculants at Ismaillia Governorate in northeast Egypt in comparison with the chemical N-fertilization treatment (96 kg N·ha−1). A starter N-dose (48 kg N·ha−1) was applied in combination with different Rhizobium inoculants. The field experiments were established at sites without a background of inoculation under low fertility sandy soil conditions over two successive winter growing seasons, 2012/2013 and 2013/2014. Under greenhouse conditions, inoculated plants produced significantly higher nodules dry weight, plant biomass, and shoot N-uptake than non-inoculated ones. In the first season (2012/2013), inoculation of field-grown faba bean showed significant improvements in seed yield (3.73–4.36 ton·ha−1) and seed N-yield (138–153 Kg N·ha−1), which were higher than the uninoculated control (48 kg N·ha−1) that produced 2.97 Kg·ha−1 and 95 kg N·ha−1, respectively. Similarly, in the second season (2013/2014), inoculation significantly improved seed yield (3.16–4.68 ton·ha−1) and seed N-yield (98–155 Kg N·ha−1) relative to the uninoculated control (48 kg N·ha−1), which recorded 2.58 Kg·ha−1 and 80 kg N·ha−1, respectively. Interestingly, faba bean inoculated with strain Rlv NGB-FR 126 showed significant increments in seed yield (35%–48%) and seed N-yield (34%–49%) compared to the inorganic N fertilizers treatment (96 kg N·ha−1) over the two cropping seasons, respectively. These results indicate that inoculation of faba bean with effective rhizobial strains can reduce the need for inorganic N fertilization to achieve higher crop yield under low fertility soil conditions.

Highlights

Faba bean (Vicia faba L., broad bean, horse bean) is a major grain legume widely cultivated in many countries for food and feed purposes [1]
(96 kg N·ha−1 ) over the two cropping seasons, respectively. These results indicate that inoculation of faba bean with effective rhizobial strains can reduce the need for inorganic N fertilization to achieve higher crop yield under low fertility soil conditions
The symbiotic efficiency of 17 rhizobial strains related to Rhizobium leguminosarum sv. viciae (Rlv) and A. tumefaciens was assessed with faba bean cv

Summary

Introduction

Faba bean (Vicia faba L., broad bean, horse bean) is a major grain legume widely cultivated in many countries for food and feed purposes [1]. Due to its multiple uses, high nutritional value, and ability to grow over a wide range of climatic and soil conditions, cultivation of faba bean is suitable for sustainable agriculture in many marginal areas [2]. Faba bean is one of the oldest legume crops grown in Egypt [3]. Production has declined considerably from 523,000 tonnes in 1998 to 158,000 tonnes in 2014 [4]—often a result of susceptibility to foliar diseases, the effects of parasites [5], and/or competition with other crops. Egypt now is the world’s largest importer of faba bean; its annual requirement of half million tonnes accounts for over half of global imports [6]. Increasing faba bean production and improving yield quality is a major target to meet the demand of the increasing Egyptian population, since faba bean constitutes a major part of the diet of Egyptian people [7]

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Conclusion