Nodulation and root growth increase in lower soil layers of water‐limited faba bean intercropped with wheat

Abstract

Below‐ground niche complementarity in legume–cereal intercrops may improve resource use efficiency and root adaptability to environmental constraints. However, the effect of water limitation on legume rooting and nodulation patterns in intercropping is poorly understood. To advance our knowledge of mechanisms involved in water‐limitation response, faba bean (Vicia faba L.) and wheat (Triticum aestivum L.) were grown as mono‐ and intercrops in soil‐filled plexiglass rhizoboxes under water sufficiency (80% of water‐holding capacity) and water limitation (30% of water‐holding capacity). We examined whether intercropping facilitates below‐ground niche complementarity under water limitation via interspecific root stratification coupled with modified nodulation patterns. While no significant treatment effects were measured in intercropped wheat growth parameters, water limitation induced a decrease in shoot and root biomass of monocropped wheat. Likewise, shoot biomass and height, and root length of monocropped faba bean significantly decreased under water limitation. Conversely, water limitation stimulated root biomass of intercropped faba bean in the lower soil layer (15–30 cm soil depth). Similarly, total nodule number of faba bean roots as well as nodule number in the lower soil layer increased under intercropping regardless of water availability. Under water limitation, intercropping also led to a significant increased nodule biomass (48%) in the lower soil layer as compared to monocropping. The enhanced nodulation in the lower soil layer and the associated increase in root and shoot growth provides evidence for a shift in niche occupancy when intercropped with wheat, which improves water‐limited faba bean performance.

Factors Influencing Imazapyr Herbicide Removal from Wastewater Using Photocatalytic Ozonation

“…Similar finding have been reported by Usharani et al, 14 and by Gar Alalma et al 15 These authors have reported first order reaction kinetics for the degradation and mineralization of chlorinated pesticides and insecticides and other various water pollutants by photocatalytic ozonation. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The results, shown in figure 5, demonstrates that the optimal conditions for imazapyr degradation with photocatalytic ozonation is neutral pH. On the other hand, the combination of two oxidation systems, ozonation and photocatalysis, for water treatment under optimal conditions are reported to have increased oxidation efficiencies (synergy) compared to the sum oxidation efficiencies of these two oxidation systems separately.…”

“…The optimal amount of Hombikat UV 100 agrees well with reported results by other authors. [14][15][16][17][18][19][20][21][22][23][24][25][26] This improvement can be attributed to the increasing of active sites by providing more TiO 2 particles, which plays the semiconductor role in the photocatalysis process. Consequently, the formation of electron-hole pairs and reactive hydroxyl radicals on the surface of semiconductor increased, which improved the oxidation of imazapyr into other intermediates.…”

“…Consequently, the formation of electron-hole pairs and reactive hydroxyl radicals on the surface of semiconductor increased, which improved the oxidation of imazapyr into other intermediates. [15][16][17][18][19][20][21][22][23][24][25][26][27] …”

“…A possible explanation resides in the fact that as imazapyr concentration rises, it is possible that more organic substances are deposed on the surface of TiO 2 , whereas less number of photons are available to reach the catalyst surface and the probability of reaction between imazapyr molecules and oxidizing species also decreases, thus resulting in less degradation percentage. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] …”

“…[10][11][12] However, The degradation of Imazapyr has also been investigated by other authors using photocatalysis and ozone and results showed lower concentration compared to photocatalytic ozonation. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The photocatalytic ozonation degradation of pesticides is largely dependent on operating parameters such as TiO 2 dosage, initial herbicide concentration and solution pH. [31][32] Understanding the effects of these factors on the photocatalytic degradation efficiency have an importance when designing a sustainable and efficient technique for wastewater treatment.…”