Ecosystem Services Provided by Cover Crops and Biofumigation in Sunflower Cultivation

In south-western France, sunflowers are usually grown in short rotations and after a long fallow period during which soils are left bare. This practice can favour diseases, caused by soilborne fungi, such as sunflower verticillium wilt (SVW), as well as nitrate leaching, both of which can decrease yields. Growing cover crops during a fallow period is an agroecological practice that could provide ecosystem services and mitigate SVW. A Brassicaceae cover crop that causes biofumigation produces glucosinolates and liberate biocidal compounds that might regulate SVW biologically. Moreover, the green manure effect of the Fabaceae might increase soil mineral nitrogen (SMN). To go further, mixtures of Brassicaceae and Fabaceae might mutualise the benefits that each cover crop has in sole crops. A four-year field study in south-western France tested Brassicaceae (brown mustard, turnip rape and fodder radish) and Fabaceae (purple vetch) in sole crops or a mixture with two or three species during the fallow period, followed by biofumigation, and sunflower crop. The cover crops were characterised, SMN was measured, the SVW and yield were assessed and compared to those of the crop grown on soils left bare during the fallow period. Purple vetch as a sole crop cover crop significantly increased SMN before sunflower sowing but only in 2019. Fodder radish as a sole crop reduced SVW severity significantly, overall, 80 days after sowing, except in 2019, when weather conditions were unfavourable to biofumigation. Purple vetch as a sole crop also reduced significantly SVW severity in 2017 and 2020. Finally, sunflower yields after cover crops were higher than those after bare soils, only after purple vetch as a sole crop in 2020, with a mean increase of 0.77 t ha−1. Mixtures of Brassicaceae and Fabaceae sowed at these densities resulted in an intermediate SMN level between those in sole crops and the bare soil and they did not significantly decrease SVW or increase yields. Our results suggest that cover crops, especially fodder radish or purple vetch, and biofumigation can provide ecosystem services for sunflower, instead of leaving soils bare during the fallow period. However, the extent of ecosystem services is markedly affected by soil and climatic conditions as well as other management practices.

Upland rice intercropped with green manures and its impact on the succession with common bean

The aim of this work was to verify the possibility of intercropping rice with green manures, as well as the impact of the dry biomass yield of these intercropping systems on common bean in succession, evaluating the agronomic and qualitative performance of grains from both crops. The experiment was conducted in Southeastern Brazil in the years 2018 and 2019, with succession of rice (spring/summer) and common bean (autumn/winter). The treatments were composed of cropping systems with rice as a sole crop and intercropped with forage peanut, calopo, Crotalaria breviflora, Crotalaria spectabilis, stylo, jack bean and dwarf pigeon pea. No intercropping increased the system's yield compared to sole-crop rice, but intercropping of rice with forage peanut and stylo promoted grain yield and quality similar to those of sole-crop rice. Intercropping with C. breviflora affected the agronomic and qualitative performance of rice. Common bean yield after rice intercropped with dwarf pigeon pea, C. spectabilis and C. breviflora was similar in yield after sole-crop rice, while the other intercrops reduced common bean yield. Common bean grain quality was not affected by the cultivation of rice as sole crop and intercropped with green manures. Although none of the intercropping systems increased yield compared to sole-crop rice (control), it can be concluded that the intercropping of upland rice is viable depending on the green manure species, allowing greater biomass production per area that can help long-term soil conservation and increase the system's yield.

Intercropping and Nitrogen Fertilization Altered the Patterns of Leaf Senescence in Sorghum

Leaf senescence regulates grain yield. However, the modulation of leaf senescence in sorghum under legume-based intercrop systems and nitrogen (N) fertilization is not known. The objective of the study was to investigate the effect of intercropping two sorghum (Gadam and Serena) and cowpea (K80, M66) varieties and sole cropping systems and different fertilizer N rates (0, 40, and 80 kg·N·ha−1) on the time course of postflowering sorghum leaf senescence and understand how senescence modulates grain yield. The experiment was laid out in a randomized complete block design with a split-plot arrangement with three replications. Leaf senescence was assessed from flowering to maturity at (a) whole-plant level by the visual scoring of green leaves and (b) flag leaf scale by measuring leaf greenness with a SPAD 502 chlorophyll meter. A logistic function in SigmaPlot was fitted to estimate four traits of leaf senescence, including minimum and maximum SPAD (SPADmin, SPADmax), time to loss of 50% SPADmax (EC50), and the rate of senescence. Irrespective of the cowpea variety, intercropping reduced sorghum grain yield by 50%. The addition of N increased yield by 27% but no effect was detected between 40 and 80 kg·N ha−1. Intercropping delayed leaf senescence at the whole plant by 0.2 leaves plant−1 day−1 but reduced SPADmax of the flag by 8 SPAD units and rate of senescence by 4 SPAD units day−1 compared with sole crop system. Fertilizer N delayed leaf senescence ( P ≤ 0.05 ) at whole-plant and flag leaf scales. Cropping System × nitrogen modulated senescence at whole-plant and flag leaf scales and sorghum grain yield but marginally influenced other traits. While EC50 did not correlate with grain yield, faster rates of senescence and leaf greenness were associated with high yield under the sole crop system. Overall, N was the main factor in driving sorghum leaf senescence while the intercropping effect on senescence was nonfunctional. Effects of competition in sorghum-legume intercropping and source-sink relationships on the patterns of leaf senescence deserve further investigation.

Influence of Light Parameters on Photosynthetic Rate of Sorghum Based Intercropping System

Selecting the appropriate row proportion in the intercropping system is required for the effective harnessing of solar radiation. In Semi-arid areas, Sorghum based intercropping is commonly adopted by the farmers for effective utilization of the available resources. The treatments consisted of T1-Sorghum Sole crop (SS), T2-2rows of Sorghum+2rows of Cowpea (2S:2C), T3-2rows of Sorghum+1row of Cowpea (2S:1C), T4-2rows of Sorghum+2rows of Greengram (2S:2G), T5-2rows of Sorghum+1rows of Greengram (2S:1G), T6-2rows of Sorghum+2rows of Lablab (2S:2L), T7-2rows of Sorghum+1rows of Lablab (2S:1L). The results of the study showed that sorghum under 2:1 pattern had enhanced LAI, Radiation absorption efficiency which resulted in a high photosynthetic rate. The intercrops under 2:2 pattern were suffered from shading of sorghum than 2:1 pattern which affected the photosynthetic rate of intercrops under 2:2 pattern. Hence, planting sorghum under 2:1 pattern with Lablab will be the ideal row ratio to harness maximum sunlight.

Cultivar Grain Yield in Durum Wheat-Grain Legume Intercrops Could Be Estimated From Sole Crop Yields and Interspecific Interaction Index

Ensuring food security for a world population projected to reach over nine billion by 2050 while mitigating the environmental impacts and climate change represent the major agricultural challenges. Diversification of the cropping systems using notably cereal–legume mixtures is one key pathway for such agroecological intensification. Indeed, intercropping is recognised as a practice having the potential to increase and stabilise the yields in comparison with sole crops while limiting the use of inputs notably when species exploit resources in a complementary way. However, predicting intercropped species grain yield remains a challenge because the species respond to competition through complex genotype x cropping mode interactions. Here, we hypothesised that the grain yield achieved by a cultivar in low nitrogen input durum wheat–grain legume intercrops (ICs) could be estimated using a few simple variables. The present work is based on a 2-year field experiment carried out in southwestern France using two durum wheat (Triticum turgidum L.), four winter pea (Pisum sativum L.), and four winter faba bean (Vicia faba L.) genotypes with contrasting characteristics, notably in terms of height and precocity, to explore a wide range of durum wheat–grain legume phenotypes combinations to generate variability in terms of yield and species proportion. The major result is that the yield of durum wheat–grain legume IC component in low nitrogen input conditions could be correctly estimated from only three variables: (i) wheat cultivar full density sole crop (SC) yield, (ii) legume cultivar half density sole crop (SC½) yield, and (iii) an indicator of legume cultivar response to interspecific competition. The latter variable, the interspecific interaction index (IE), reveals cultivars' competitive abilities and tolerance to competition. However, to propose generic IC design and management procedures, further mechanistic understanding is required to better understand the links between tolerance to interspecific competition and cultivar phenotype characteristics. In particular, a special emphasis on the grain legume is needed as their response to interspecific competition appears less predictable than that of durum wheat. Cultivar choice is a key element to optimise the functional complementarity and subsequent IC advantages. This work proposes a simple tool to assist the design of specific breeding programs for cultivars ideotypes adapted to intercropping.

Potential of Sunflower-Legume Intercropping: A Way Forward in Sustainable Production of Sunflower in Temperate Climatic Conditions

Changing climate conditions coupled with the transformations of cultivation practices and land use in sole crop-based sunflower production may significantly decline yield stability of this oilseed crop. Given that sunflower takes the third place in the world oilseed market, with 45 million tons per year, and in the fourth place in vegetable oil production, it is necessary to adapt production technologies toward sustainable agriculture. Considering that, the goal of the research was to analyze and beneficial sustainable production technology of sunflower in intercropping systems. A four-year trial was conducted in Serbia’s agroecological rain-fed conditions (45°34’23.2"N 19°86’18.9"E) using a split-plot design. Two oil types and one confectionary sunflower hybrid were intercropped with common vetch, red clover and alfalfa. Analyses showed that intercropping of sunflower with common vetch resulted in the decrease in almost all sunflower trait values. Also, sunflower × alfalfa intercropping provided to be the most appropriate. The yield of NS Gricko and Rimi PR were statistically on the same level with sole cropping, while alfalfa biomass had better results when intercropped with NS Gricko as compared to sole cropping. Concerning the general belief that yields are more stable in intercropping than in sole crop, further research in this respect is needed, in addition to the research of time and method of sowing.

Influence of Intercropping on Larval Population of Chickpea Pod Borer, Helicoverpa armigera (Hub.) in Chickpea (Cicer arietinum L.)

A field experiment on influence of intercropping on the larval population of chickpea pod borer, Helicoverpa armigera (Hub.) in chickpea was conducted at Agricultural Research Farm of Brahmanand Post Graduate College, Rath, Hamirpur, Uttar Pradesh during 2016-17 and 2019-20. In Bundelkhand agro-climatic region the activity of chickpea pod borer was observed from last week of December to last week of March while, its peak activity was noticed at 9th, 10th and 11th SMW in chickpea agro-ecosystem. The infestation of chickpea pod borer (H. armigera) larvae was started from last week of December when the crop was in vegetative growth stage. Thereafter, its population increase gradually to reach maximum (1.72 larvae/mrl) at 10th standard (first fortnight of March) after that its population declined gradually till the harvesting of the crop. The chickpea intercropped with safflower, mustard, linseed, barley and marigold had significant influence in reducing the larval population of chickpea pod borer (H. armigera). The chickpea intercropped with marigold (0.71larva/mrl) and mustard (0.75larva/mrl) was found the most effective in reducing the larval population of H. armigera. It was followed by chickpea + linseed, chickpea + barley and chickpea + safflower intercropping systems. The maximum population of chickpea pod borer was observed in chickpea sole crop (1.07larvae/mrl).

Effect of sowing proportion on above- and below-ground competition in maize–soybean intercrops

The relative contribution of above- and below-ground competition to crop yield under intercropping systems is critical to understanding the mechanisms of improved yield. Changes in the content of above- and below-ground biomass, leaf photosynthetic rate (Pn), leaf area index (LAI), chlorophyll meter reading (SPAD), diffuse non interceptance (DIFN), soil water storage (SWS), crop nitrogen (N), and phosphorus (P) uptake were examined in a 2-year trial of different maize–soybean intercropping systems on the Loess Plateau, China. Compared with the sole cropping system, shoot biomass of maize was increased by 54% in M2S2 and 62% in M2S4 strip intercropping treatment. The crop N and P uptake of maize increased significantly, by 54% and 50% in M2S2 and by 63% and 52% in M2S4 compared with their respective sole crop. LAI values of maize in intercropping systems were 14% and 15% for M2S2 and M2S4 less than that in the sole crop. The DIFN of intercropped maize was increased by 41% and 48% for M2S2 and M2S4 compared to monocrop. There were no significant differences in Pn and SWS in both crops between the two cropping systems. The contribution rate of DIFN in M2S2 and crop P uptake in M2S4 on the biological yield in intercropping system was the highest among all factors. We conclude that the sowing proportion affects above- and below-ground competition in maize–soybean intercropping systems.

Crop succession and split-application of nitrogen effects on common bean yield in short no-tillage system

Evaluating the effects of crop successions in no-tillage system (NTS) is essential for the correct recommendation of agronomic practices, such as top-dressing nitrogen fertilization. The aim was to evaluate the effect of the crop succession and the splitting of top-dressing N fertilization on the agronomic performance and economic viability of common bean crop. The experiment was conducted in southeastern Brazil for two agricultural seasons in an area under NTS, using a split-plot in randomized complete block design. The plots represented three cropping successions (maize in sole crop, maize intercropped with Urochloa ruziziensis and U. ruziziensis in sole crop) and the subplots composed of ten combinations of splitting of top-dressing N, at the stages V3, V4 and R5 of the common bean crop. In relation to the single application of the N dose of 90 kg ha−1, the common bean had higher response as a function of the N splitting schemes adopted, regardless of the previous cropping succession. The cropping successions evaluated did not interfere with the seed yield of common bean as subsequent crop, even at the beginning of the establishment of NTS. To obtain higher seed yield and economic viability, the N dose of 90 kg ha−1 indicated for the crop must be split and applied among the phenological stages V3, V4 and R5.

Growth and dry matter partitioning response in cereal-legume intercropping under full and limited irrigation regimes

The dry matter partitioning is the product of the flow of assimilates from the source organs (leaves and stems) along the transport route to the storage organs (grains). A 2-year field experiment was conducted at the agronomy research farm of the University of Agriculture Peshawar, Pakistan during 2015–2016 (Y1) to 2016–2017 (Y2) having semiarid climate. Four summer crops, pearl millet (Pennisetum typhoidum L.), sorghum (Sorghum bicolor L.) and mungbean (Vigna radiata L.) and pigeonpea (Cajanus cajan L.) and four winter crops, wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), fababean (Vicia faba) and rapeseed (Brassica napus) were grown under two irrigation regimes (full vs. limited irrigation) with the pattern of growing each crop either alone as sole crop or in combination of two crops in each intercropping system under both winter and summer seasons. The result showed that under full irrigated condition (no water stress), all crops had higher crop growth rate (CGR), leaf dry weight (LDW), stem dry weight (SDW), and spike/head dry weight (S/H/PDW) at both anthesis and physiological maturity (PM) than limited irrigated condition (water stress). In winter crops, both wheat and barley grown as sole crop or intercropped with fababean produced maximum CGR, LDW, SDW, S/H/PDW than other intercrops. Among summer crops, sorghum intercropped either with pigeon pea or with mungbean produced maximum CGR, LDW, SDW, and S/H/PDW at both growth stages. Sole mungbean and pigeon pea or pigeon pea and mungbean intercropping had higher CGR, LDW, SDW, S/H/PDW than millet and sorghum intercropping. On the other hand, wheat and barley grown as sole crops or intercropped with fababean produced maximum CGR, LDW, SDW, and S/H/PDW than other intercrops. Fababean grown as sole crop or intercropped with wheat produced higher CGR, LDW, SDW, and S/H/PDW at PM than intercropped with barley or rapeseed. From the results it was concluded that cereal plus legume intercropping particularly wheat/fababean in winter and sorghum/pigeon pea or sorgum/mungbean in summer are the most productive intercropping systems under both low and high moisture regimes.