Exploiting Plant Functional Diversity in Durum Wheat–Lentil Relay Intercropping to Stabilize Crop Yields under Contrasting Climatic Conditions

Relay intercropping is considered a valuable agroecological practice to increase and stabilize crop yields while ensuring the provision of several ecosystem services as well as sustainability and resilience to changing climatic conditions. However, farmers are still reluctant in the use of intercropping practices since there is a huge knowledge gap regarding the time of sowing, sowing ratio, crop stand density, and cultivar choice. In this study, we carried out a 3-year field experiment in Central Italy to assess the effect of relay intercropping on the agronomic performance and competitiveness of winter durum wheat (Triticum durum Desf. cv. Minosse) and spring lentil (Lens culinaris Medik. cv. Elsa) under a low-input management system, comparing different crop stand types (monocrop vs. intercrop) and target plant densities (350 plants m2—full dose vs. 116 plants m2—1/3 dose). The results revealed that intercropping increased grain yield compared to monocropping: significantly (p < 0.0001) against both monocrops in 2021 and non-significantly against durum wheat in 2019 and 2020. Yield advantage in both intercropping systems ranged between 164 and 648%. Durum wheat competitiveness was stronger in 2019 and 2021, while lentil was the most competitive component in 2020. Intercropping favored P accumulation in durum wheat shoots. There was no difference in grain yield of both crops between the highly- and lowly-dense system in 2020 and 2021. Both intercropping strategies were as effective as mechanical hoeing in controlling weeds and proved beneficial in stabilizing lentil productivity. Further economic analysis capturing the additional costs incurred in intercropping and mechanical weeding would highlight the magnitude of profitability of these systems.

Yield, quality, antioxidants and elemental composition of peanut as affected by plant density and harvest time

With the perspective of reintroducing peanut cultivation in southern Italy about six decades after its dismissal, research was carried out with the aim to identify the best performing farming management in terms of yield and quality. In this respect, the effect of the factorial combination between four plant densities (6.1, 7.8, 10.3, and 12.1 plants m-2) and two harvest times (100 and 110 days after planting) was assessed on pod and seed yield, as well as on seed quality, antioxidant activity, and elemental composition. The later harvest time determined a 26.9% dry weight increase, but a 14.3% decrease in the number of seeds per pod. Plant density significantly influenced all the yield and growth indices except for mean seed weight. Yield and growth of each plant were best affected by the lowest plant density, whereas the opposite trend was recorded for the same parameters referred to the surface area unit. The density of 12.1 plants m-2 resulted in a 32% reduction in pods per plant compared to 6.1 plants m-2, but had the greatest effect on seed production per m-2. The leaf area index was the highest with the density of 12.1 plants m-2. The total dry weight increased by 1.7-fold from 6.1 to 12.1 plants m-2. Compared to the first harvest time, in the second one the protein content decreased by 6.8%, and total polyphenols and antioxidant activity decreased by 11.2% and 7.6%, respectively. The second harvest time led to a depletion of N, P, and Mg, by 6.8%, 6.2%, and 6.8%, respectively, and a 7.1% Ca increase. The reintroduction of peanut cultivation in southern Italy is a realistic goal, though further studies regarding the crop system management are needed.

Mixed Cropping of Dwarf Napiergrass (Pennisetum purpureum cv. Mott) with Indigofera (Indigofera zollingeriana) using an Alley Cropping System

Background: Mixed cropping of forage grasses and legumes can potentially improve the performance of herbivores. However, the feasibility of grasses mixed-cropped with legumes should be examined at different plant densities. Aim: This study aimed to evaluate the growth characters and forage chemical composition in dwarf napiergrass (Pennisetum purpureum cv. Mott) with Indigofera (Indigofera zollingeriana) grown using alley cropping. Methods: Three densities of dwarf napiergrass with Indigofera, i.e., high density (2 and 1 plants m-2, respectively); medium density (1.33 and 1 plants m-2, respectively); and low density (1 and 1 plants m-2, respectively) were applied under rainfed conditions in Makassar. Results: Plant density significantly affected growth characteristics, such as plant height and tiller density in dwarf napiergrass (p<0.05), and non-significantly affected plant height and branch density (p>0.05) in Indigofera. Plant density did not affect the yielding ability at the first defoliation and annual total of yields (p>0.05), except at the second defoliation when the dry matter production of dwarf napiergrass peaked in the low plant density treatment (p<0.05). In terms of chemical composition, plant density significantly affected fiber concentrations of acid detergent fiber and neutral detergent fiber, which were lowest at low plant densities (p<0.05). The acid detergent lignin and cellulose concentrations tended to be lower at low plant densities, but the differences were not significant (p>0.05). Conclusion: We consider that alley cropping systems for dwarf napiergrass and Indigofera are suitable if low plant densities are employed in the region.

Boll characteristics and yield of cotton in relation to the canopy microclimate under varying plant densities in an arid area

Planting density affects crop microclimate and intra-plant competition, playing an important role on yield formation and resource use, especially in areas where the cotton is grown at relatively high plant densities in Xinjiang, China. However, more studies are needed to examine how the change in planting density affects the microclimate factors such as the fraction of light intercepted (FLI), air temperature(T) and relative humidity (RH) within different canopy layers, which in turn affect the boll number per plant (BNF), boll number per unit area (BNA), boll weight (BW), and boll-setting rate (BSR) at fruiting branch (FB) positions FB1–3, FB4–6, and FB≥7 in cotton. To quantify the relationships between boll characteristics, yield, and microclimate factors, we conducted a 2-year field experiment in 2019–2020 in Xinjiang with six plant densities: 9 (P1), 12 (P2), 15 (P3), 18 (P4), 21 (P5), and 24 (P6) plants m−2. With each three plants m−2 increase in density, the average FLI and RH across different canopy layers increased by 0.37 and 2.04%, respectively, whereas T decreased by 0.64 °C. The BNF at FB≥ 7, FB4–6, and FB1–3 decreased by 0.82, 0.33, and 0.5, respectively. The highest BNA was observed in the upper and middle layers in the P4 treatment and in the lowest canopy layer with the P5. The highest BW was measured in the middle canopy layer for P3, and the highest BSR was measured in the lower layer for P3. Plant density exhibited linear or quadratic relationships with FLI, T, and RH. Microclimate factors mainly affected the boll number in each layer, but had no significant effects on the BW in any layer or the BSR in the middle and lower layers. Cotton yield was non-linearly related to plant density. The 2-year maximum yield was achieved at a plant density of 21 plants m−2, but the yield increase compared to the yield with a density of 18 plants m−2was only 0.28%. Thus, we suggest that the optimal plant density for drip-irrigated cotton in Xinjiang is 18 plants m−2, which could help farmers grow machine-harvested cotton.

Study of Yield and its Components for Several Genotypes of Durum Wheat (Triticum Durum L.) Newly Derived Under Three Seeding Rate in the Conditions of Anbar Governorate

A field experiment was carried out in a farmer’s field in Zakhikha which is one of the rural areas of western Heet City (about 15 kg) in Anbar Governorate, during Winter season 2020-2021, with sandy loam soil, to study seven newly derived genotypes from durum wheat, including two cultivars. They are registered, certified, and commonly cultivated in Iraq, under three seeding rate to select the ones that are suitable for the conditions of Anbar Governorate. Randomized complete blocks design (RCBD) was used in a split plot arrangement with three replications. The experiment included three Seeding rate (140, 160 and 180 kg ha-1) that represented the main plot, whereas the sub plots were occupied by seven genotypes (Latifia, Babel-30, Babel-31, Babel-32, Babel-86, and the two approved varieties Dour-29 and Dour-85). The results of the study showed that Babel-32 outperformed the rest of significant effect genotypes with highest average number of spikes (507.6 spike m-2) and grain yield (8.741 Mg ha-1), while the genotype Babel-86 was superior in weight of 1000 grain (55.89 g), and the cultivar (Dour-29) outperformed for the trait of number of grains per spike (39.15 grains spike-1). A significant effect of plant densities appeared in the studied traits, as the plants grown at seeding rate (180 kg ha-1) recorded the highest average in the trait of number of spikes m-2 (506.2 spike m-2) and grain yield (8.898 Mg ha-1) And the percentage of protein (11.89%). While planting plants at seeding rates (140 kg ha-1) led to the highest rate of number of grains per spike (38.42 grains) and 1000 grains weight (52.71 g). There was a significant interaction between genotypes and Seeding rate.

Genetic Analysis by Using Partial Diallel Crossing of Maize In High Plant Densities (Estimation GCA, SCA and Some Genetic Parameters)

The experiment was carried out at the Field Crops Research Station, College of Agricultural Engineering Sciences - University of Baghdad in Jadiriyah, with the aim of evaluating the performance of partial diallel hybrids and inbred lines of maize and estimating general combining ability(GCA), specific combining ability (SCA) and some genetic parameters. The experiment was carried out in two seasons, spring and fall 2020. Eight inbred lines of maize were used in the study (BI9/834, BSW18, LW/5 L8/844, ZA17W194, Z117W, ZI17W9, ZI7W4), numbered (1,2,3,4,5,6,7,8), It was sowed in the spring season and entered into a cross-program according to a partial diallel crossing system to obtain twelve partially cross-hybrids, and it was compared with its eight parents in a comparison experiment in the fall season using a Randomized Complete Block Design (RCBD) with split plots arrangement with three replication. The plant densities of 70 and 90 thousand plants ha-1 represented the main plots, while the partial diallel hybrids and their parents represented the secondary plots. The results of the study showed that the ratio between GCA and SCA) GCA/SCA) It was more than 1 for yield traits, ear length, number of rows and number of row grains in both low and high densities, which indicates the control of the additive genetic action on these traits. While the ratio was less than one for the traits of the ear diameter under the low density, which indicates the control of dominance genes on this trait in the mentioned density, while the trait of the number of ear grains, the ratio between the general and specific combining abilities was less than one in the high density. Inbred line 8 had the highest effect for the general ability to combine under low density, which amounted to 11.075, while inbred line 2 was superior by giving the highest effect to the general ability to combine at low density, which amounted to 17.80, followed by inbred 8.

Effect of Adding Sulfur and Organic Fertilizer on Growth and Yield of Onions (Allium Cepa L.) Under Different Plant Densities

A field experiment was conducted in the Amiriyat al-Fallujah district of the Anbar governorate to know the effect of the combination of sulfur and organic fertilizer on the growth and yield of onion, (a local red type), under different plant densities. The experiment included two factors, first: a combination of fertilizing with decomposing Cow’s manure (20 tons.ha-1) and sulfur (50 kg.ha-1), and this factor was distributed as follows (T0: fertilizer recommendation (NPK 100-100-120 kg.ha-1 It is considered a control). T1: cow waste + half of the chemical fertilizer recommendation and T2: fertilizer recommendation + sulfur addition and T3: Cow’s manure + half of the fertilizer recommendation + sulfur addition and T4: double the recommendation of cow manure (40 t.ha-1 + half of the fertilizer recommendation + adding sulfur). The second factor: planting distances (S1:10×10, S2:10×15, and S3:10×20) cm. The distance between plants was fixed 10 cm and the dimensions changed between one line and another. The study was carried out as a factorial experiment with the randomized complete block design (RCBD). The results showed clear significant differences for the two study factors in characteristics of vegetative growth, yield, and the content of total soluble solids, as the T4S3 treatment exceeded by giving it the highest number of tubular blades, leaf area and the highest percentage of sulfur in the leaves, which was positively reflected on the plant yield and percentage the total soluble solids amounted to (16.57 blades.plant-1, 15.97 dm2, 1.70%, 0.64%, 104.50 g, 15.83%), respectively, The treatment of planting distances S1 achieved significant differences in the total yield (90.39 tons.ha-1 and 8.91 kg) respectively compared to plants of treatment S3, which achieved(74.29 tons.ha-1and 5.39 kg).

Natural toxins: environmental contaminants calling for attention

Biosynthetic toxic compounds from plants and cyanobacteria constitute a chemically diverse family of at least 20,000 compounds. Recent work with natural toxin databases and toxin characterization shows that the majority of natural toxins are polar and mobile, with toxicity ranging from low to very high, while persistence is highly variable. Natural toxins may be produced in high quantities—some exceeding 10 g/m2/year—resulting in high environmental loads. Recent phytotoxin monitoring indicates that one or more natural toxin is always present in a surface water sample, but that concentrations are highly variable often with pulses during rain events. Phytotoxins belong to many classes, but often with flavonoids and alkaloids dominating. Likewise, advanced monitoring discovers a wide spectrum of cyanobacterial metabolites that are released directly into surface waters during water blooms. Except of the few known cyanobacterial toxins, we have very limited info regarding their environmental fate and toxicity.The 16 papers in this article collection present examples of natural toxin occurrence, properties, fate and toxicity. The overarching conclusion is that natural toxins should be monitored and characterized regarding their risk potential, and that natural toxins of greatest expected risk should be evaluated as thoroughly as industrial xenobiotics. Cyanotoxins are well known water contaminants that should be removed for producing drinking water, while for phytotoxins the current knowledge base is very limited. We advocate to intensify research on natural toxins, and to address the evident knowledge gaps on natural toxin analysis/monitoring, physical–chemical properties and degradation/pathways, transport modelling, and toxicity. The complex and dynamic interplays between biotic and site conditions such as vegetation, toxic plant densities, climate, soil types, nutrients and radiation, play decisive roles for both biotoxin formation and fate. Environmental and toxicological research in biosynthesized compounds extends beyond natural toxins, with important perspectives for risk assessment of biopesticides, growth regulators and biomedicine (or biologicals collectively) produced by plants and microorganisms.

Growth, yield and quality of two guar (Cyamopsis tetragonoloba L.) ecotypes affected by sowing date and planting density in a semi-arid area

The growth period, phenology, grain yield and gum content of two different guar ecotypes were studied in response to different sowing dates and plant densities. A two-year field experiment was conducted as a split-factorial in a randomized complete block design (RCBD) with three replicates in the research field of Tarbiat Modares University during 2016 and 2017 growing season. Main plots consisted of four sowing dates (May 21, June 4, June 21 and July 5 in 2016 and May 10, May 26, June 10 and June 26 in 2017), and subplots including three plant densities (13, 20 and 40 plants m-2) and two ecotypes (Pakistani and Indian). Based on findings, the phenological traits, plant height, grain yield and harvest index were significantly affected by plant density. The effect of ecotypes was statistically significant (p<0.05) on all traits except harvest index in the first year. Furthermore, the seed sowings on May 21 and May 26 with 13 plants m-2 led to highest grain yield (3004.8 and 2826.10 kg.ha-1 for two consecutive years). The high gum content (33.68 and 33.78% for two consecutive years) was also recorded for Pakistani ecotype while for gravity, Indian ecotype showed higher value in both crop years. By and large, the Pakistani ecotype showed better response compared to the Indian one in both years, especially in 1st and 2nd sowing dates.