Evaluation of Silicon Supplementation for Drought Stress under Water-Deficit Conditions: An Application of Sustainable Agriculture

Drought is a key abiotic stress that confines agriculture development worldwide. Silicon (Si) is commonly considered to be a valuable element for resistance against drought and for sustainable agriculture. To investigate the morpho-physiological and biochemical characteristics of Gerbera jamesonii plants, a pot experiment was conducted under greenhouse conditions and exposed to water stress (60% FC) and well-watered (100% FC) conditions. Foliar application of Si was carried out after ten days (48 days after sowing) of drought treatment and was repeated weekly, while well-water was regarded as control. Water deficiency significantly abridged the morphological attributes, pigments, and stress-related metabolites and negatively affected the photosynthetic apparatus in drought-stressed gerbera plants. However, Si supplementation by 40 mg L-1 produced increased leaf area (31%), stem length (25%), flower diameter (22%), plant fresh biomass (17%), total chlorophyll (48%), and concentration of carotenoids (54%) in water-stressed plants. Similarly, the accretion of a total free amino acid (41%) and the activities of peroxidase, catalase, superoxide dismutase, ascorbate peroxidase, glycinebetaine, total soluble proteins, total free proline, and malondialdehyde were enhanced by 44%, 31%, 53%, 33%, 330%, 61%, 51%, and 66%, respectively, under drought stress in comparison with control conditions. Meanwhile, the photosynthetic rate (89%), the transpiration rate (12%), and stomatal conductance (55%) were significantly enhanced in water-deficit gerbera leaves with Si supplementation. This study proposes that the foliar application of Si is a viable and convenient method of improving the performance of elegant gerbera flower plants in regions of the world that are facing severe water deficiency

Floristic composition and species diversity of weed community after 10 years of different cropping systems and soil tillage in a Mediterranean environment

Sustainable cropping systems based on low inputs have received much attention, even if they may lead to the establishment of a competitive weed flora. This study, conducted from 2011 to 2014 in a Mediterranean environment, evaluated the changes in weed community composition in two cropping systems [conventional (CONV) and organic (ORG)] with different soil tillage [inversion tillage (IT) and non-inversion tillage (NoIT)] in a wheat–tomato–chickpea rotation that began in 2000. The treatments were replicated three times according to a randomised complete block design. The organic system was managed according to EU regulations. Inversion tillage consisted of mouldboard ploughing to a depth of 30 cm, while NoIT consisted of subsoiling to a depth of 20 cm. Weed control was based on herbicide application in CONV and mechanical weeding in ORG. The organic non-inversion system showed the highest weed biomass (134, 128 and 195 g dry matter (DM) m−2 in wheat, tomato and chickpea, respectively) and weed density (66, 77 and 76 plants m−2 in wheat, tomato and chickpea, respectively), as well as community richness. However, ORG always increased weed diversity, even if annual dicotyledon species were abundant in ORG-IT and perennial dicotyledon species in ORG-NoIT. The conventional system enhanced the relative frequency of both annual (CONV-IT) and perennial (CONV-NoIT) grasses. There was a negative correlation between density of perennial weeds and crop yield (r2 = 0.24, P < 0.001). Therefore, in the Mediterranean environment, combining organic practices with non-inversion tillage could lead to the establishment of perennial weeds that are difficult to control, thus requiring specific weed management practices

Quality of tomato (Solanum lycopersicum l.) changes under different cover crops, soil tillage and nitrogen fertilization management

The purpose of this study was to evaluate the interaction effects of winter cover crops (hairy vetch, subclover and black oat) and a bare soil, cover crop biomass management (incorporated into the soil or left on the soil surface as death mulch), and nitrogen (N) fertilization level (0, 75 and 150 kg ha−1 of N) on fruit yield and fruit quality parameters of processing tomato. Hairy vetch residues increased the yield (+57%), color index (+8%) and sugar/acidity ratio (+7%) of marketable tomato fruits compared to bare soil regardless of cover crop biomass management. Black oat residues determined a poor marketable yield, especially in tilled soil (on average, −26%, compared to bare soil) and they had a tendentially negative effect on some parameters of tomato quality (high firmness and titratable acidity, low color index and pH). Subclover residues, when incorporated into the soil, determined similar marketable fruit yield to bare soil, although they had a more favorable effect on the color parameters of tomato fruits. The increasing of the N fertilization level from 0 kg ha−1 of N to 150 kg ha−1 of N always positively influenced the tomato yield and fruit characteristics. The results suggest that hairy vetch, compared to other cover crops, had a positive influence on tomatoes and it could be part of an environmentally friendly management package for sustainable tomato cultivation in Mediterranean conditions

How soil ecological intensification by means of cover crops affects nitrogen use efficiency in pepper cultivation

Ecological intensification, based on agricultural practices that promote ecosystem services, has been recently proposed to match crop yield and environmental concerns. Two-year experiments were conducted in a Mediterranean environment. The treatments were: (i) four intensification levels (common vetch (CV), ryegrass (RG), bare soil without Nitrogen (N) fertilization (Control-N0) and with 100 kg ha-1 ofNfertilization (Control-N100) applied during pepper cultivation), and(ii) two soil tillage [soil tillage at 15 cm and 30 cm of soil depth (ST-15 and ST-30, respectively)]. The field experiment was disposed in a randomized block design with three replications. Cover crop, soil samples, and pepper samples were collected for analysis. Soil available nitrogen increased after soil tillage, especially in CV, which showed the highest fruit yield. The reduced soil N availability in RG decreased fruit yield and N uptake. The agro-physiological efficiency of pepper was similar in common vetch and Control-N100, while it was low in ryegrass. However, the adoption of RG increased the soil organic matter more than both control treatments, which, in turn, caused a depletion of soil organic matter. Moreover, reduced tillage practices for green manuring that both cover crops arepreferable to reduce external inputs in terms of fuel saving and farming operations

Weed control strategies and yield response in a pepper crop (Capsicum annuum L.) mulched with hairy vetch (Vicia villosa Roth.) and oat (Avena sativa L.) residues

none3noOrganic mulches could be a part of a wide strategy of integrated weed management in vegetable production systems. A 2-year field experiment was carried out in Central Italy with the aim of assessing the effect of grass and legume mulches, coming from winter cover crops, combined with herbicide or mechanical hoeing on weed control, on weed community (density and aboveground biomass of each species), and yield of a pepper crop. Hairy vetch (Vicia villosa Roth), oat (Avena sativa L.) and their mixture were sown in early autumn and suppressed in May. The cover crop aboveground biomass was cut and arranged in strips which were used as beds for pepper seedlings transplanted in paired rows. A conventional treatment kept bare during the cover crop growing season with two different levels of nitrogen fertilizer on pepper (0e100 kg ha1 of N) was also included. Three weed control treatments were applied between the paired pepper rows 30 days after transplanting: a weed free treatment, glyphosate or mechanical hoeing. Dry matter production at cover crop suppression ranged from 5.3 t ha 1 in oat to 7.1 t ha1 in hairy vetch/oat mixture and the N accumulation ranged from 56 kg ha1 in oat to 179 kg ha1 in hairy vetch. Within the pepper paired rows, mulch treatments reduced weed density and biomass throughout the pepper cropping season. At harvest, weed density and aboveground biomass within the pepper paired rows ranged from 1.7 to 4.6 plants m2 and 28 and 133 gm2 of DM, respectively. Oat mulch had the highest weed suppression ability and the lowest species richness, Shannon’s index and Shannon evenness. Between the pepper paired rows the mulch treatments had the highest species richness and the most diverse weed community in chemical compared to mechanical weed control. The densities of Portulaca oleracea L. and Polygonum aviculare L. were the highest under chemical and mechanical control, respectively. The weeds did not hinder pepper production in hairy vetch and hairy vetch/oat mixture where the yield was similar to that obtained in a conventional weedfree system fertilized with 100 kg ha1 of N. Therefore the use of hairy vetch mulches in combination with reduced mechanical or chemical weed control could be a feasible strategy in order to control weeds and to produce high yields in a pepper crop.mixedCAMPIGLIA E; RADICETTI E; MANCINELLI R.Campiglia, E; Radicetti, E; Mancinelli, R

Combined effect of genotype and inter-row tillage on yield and weed control of chickpea (Cicer arietinum L.) in a rainfed Mediterranean environment

none3Chickpea is an important pulse crop in the rainfed Mediterranean area, but its competitiveness against the weeds is very low. The combination of high competitive chickpea genotypes and inter-row cultivations could be a feasible strategy for increasing weed control. A 2-year field experiment in a typical rainfed Mediterranean environment of Central Italy was carried out to assess the competitive ability of selected chickpea genotypes grown as pure stand and in mixture with natural weed infestation partially suppressed by inter-row tillage. Experimental treatments consisted in six chickpea genotypes (Alto Lazio, C1017, C133, C134, C6150 stable lines and cultivar Sultano) and four different weed managements [no weed control (weedy); 1-hoeing performed at 25 DAE (days after chickpea emergence); 2-hoeings, one performed at 25 and one at 50 DAE; weed-free]. Chickpea aboveground biomass at 25 and 50 DAE, chickpea traits at harvesting, weeds, and competition parameters were recorded at final chickpea harvesting. C6150, C1017, Sultano, and Alto Lazio gave the best seed yield in the absence of weeds (on average 2.30 t ha−1 of DM). In weedy field conditions, the natural weeds reduced seed yield from 56.1% to 75.1%, while the1-hoeing and 2-hoeing treatments reduced the yield loss from 32.5% to 56.9% and from 5.3% to 54.9%, respectively depending on the chickpea genotypes. A good level of competitive ability combined with an elevated yield potential allowed Alto Lazio to reach the highest grain yield production in weed presence. The competitive balance index (Cb) was positively correlated with the chickpea aboveground biomass and ground coverage especially in the early stage (25 DAE), and with the chickpea plant height. 2-hoeings were more effective in reducing weed infestation than 1-hoeing, even if at chickpea harvesting the weed infestation was however high (on average 223 g m−2 of DM and 65 plants m−2 of weed aboveground biomass and density, respectively). The weed aboveground biomass was mainly made up of Polygonum aviculare L. and it was positively correlated with the number of chickpea fruitless pods and negatively correlated with the chickpea seed yield. Our findings suggest that in the rainfed Mediterranean environment of Central Italy, combining highly yielding competitive chickpea genotypes with 2 inter-row hoeings, applied at 25 and 50 DAE, is a feasible strategy in order to prevent consistent chickpea seed yield reduction caused by the weeds.mixedRADICETTI E; MANCINELLI R; CAMPIGLIA ERadicetti, E; Mancinelli, R; Campiglia,

The competitive ability of different chickpea (Cicer arietinum) genotypes against Polygonum aviculare under fiald conditions

none3Polygonum aviculare L. is a troublesome weed in chickpea cultivated in theMediterranean environment of Central Italy. A 2-year field studywas carried out to evaluate the competitive ability and the yield response of different chickpea genotypes against P. aviculare. Experimental treatments consisted in six chickpea genotypes (Alto Lazio, C1017, C133, C134, C6150 stable lines and cultivar Sultano) cultivated in weed-free conditions and with P. aviculare at four densities (4, 8, 16, 32 plants m2). The competitive ability of chickpea against P. aviculare was assessed on the basis of (i) the relative biomass total (RBT); (ii) the competitive balance index (Cb), and (iii) the competitive index (CI). The chickpea seed yield in weed-free conditions ranged from 2.6 to 2.1 t ha1 of DM and was higher in C6150 and Sultano. P. aviculare caused an average chickpea seed yield loss of 14, 46, 74 and 88% at the density of 4, 8, 16, 32 plants m2 compared to the weed-free crop. The relationship between the P. aviculare density and the percentage of chickpea yield losswas described by the rectangular hyperbola model with the asymptote constrained to 100% maximum yield loss. The estimated coefficient I (yield loss per unit density as density approaches zero) was lower in C133, Sultano, and C1017. RBT was higher than 1 in all chickpea genotypes at 4 plants m2 of P. aviculare, while at higher P. aviculare densities it was similar to 1 suggesting that there is no resource use complementarity between chickpea and the weed. Generally, at the density of 50 plantsm2 the chickpea cropwas more competitive than P. aviculare at 4 plants m2 (Cb > 0), equally competitive at 8 plants m2 (Cb ¼ 0), and less competitive at 16 and 32 plants m2 (Cb < 0). No chickpea genotype achieved the objective of combining a high seed yield potential and a great competitive ability against P. aviculare. C6150 and Sultano had a high seed yield production in weed-free conditions, but they were poorly competitive against P. aviculare at intermediate and high weed infestation, while C1017 showed a satisfactory level of Cb and CI at all P. aviculare densities although its seed yield was the lowest in weed-free conditions. However, the results suggest that, from an agronomical point of view, P. aviculare plant density should be less than 4 plant m2 in order to prevent severe chickpea seed yield loss in field conditions.mixedRADICETTI E; MANCINELLI R; CAMPIGLIA E.Radicetti, E; Mancinelli, R; Campiglia, E