Number Of Crop Species Research Articles

Crop rotational diversity enhances soil microbiome network complexity and multifunctionality

Although it is widely accepted that crop rotations can alleviate the adverse effects of agricultural intensification on ecosystem functioning, the influence of rotational diversification on soil microbial diversity, network complexity, and their associations with multifunctionality remains unclear. Here, we used a 16-year field experiment to assess the effect of six cropping regimes, and their respective crop diversity index (CDI, i.e., the number of crop species in a rotation multiplied by the species per year) and management intensity (MI, i.e., the anthropogenic inputs including fertilizer use, pesticide use and fuel consumption across a 2-year cycle), on soil microbial community (bacteria, fungi and protists) and soil multifunctionality. We used 20 soil functions related to soil properties, soil basal respiration, soil enzymatic activities and soil nitrogen cycling potential to characterize soil multifunctionality. Diversified crop rotation was shown to enhance soil multifunctionality. Also, soil multifunctionality and microbial diversity increased with CDI, but were negatively correlated or had a hump-shaped relationship with MI. With the increase in CDI, microbiome network nodes, edges and degree increased, but betweenness and average path length decreased. An increase in MI was found to have a hump-shaped relationship with the topological properties of the network. Soil microbiome network complexity had a stronger effect on multifunctionality than microbiome diversity and community composition. This study illustrates that more diverse rotations under intermediate MI promoted soil multifunctionality, and highlights the crucial role of network complexity in maintaining soil functions.

The influence of climate change on rural community food crops production pattern in high humid rainforest agroecology in the southern part of Nigeria

This study investigates the impact of climate change on the crop production pattern of the rural community in the southern part of Nigeria. The crop production pattern identified from the survey was multicropping of two or more crop species on the same piece of arable farmland. It was carried out to evaluate the crop species associated with adopted multicropping practice by the community in the face of climate change and classified into foodstuff forms and dietary requirements. Data was collected in wet and dry seasons through a reconnaissance survey of walk-through diagonally and on-the-spot assessment of each of the 22 arable farmlands cultivated for the study and crop species were identified and recorded. The survey revealed 27 crop species in 15 families and the most common crop species planted were Zea mays L., Telfairia occidentalis Hook. f., Manihot esculenta Crantz, and the least been Cucurbita moschata Duchesne, Vigna unguiculata L. It also indicated that the least number of crop species was 3 and the highest 12 per arable farmland. All the crop species identified were later classified into tubers/corms; vegetables; fruits; spices; drugs; grain legumes; soup thickeners and cereals which are the common food classification/dietary combination in the community. Multicropping of crop species on the same piece of arable farmland might be considered a way out of the climate change which has continued to impact crop species yield decline in recent times. This practice necessitated by climate change provided multiple benefits to the farmer’s homestead, community and environment because each crop species require different conditions within the environment, soil nutrients and water to thrive and therefore a balance in the agroecosystems dynamics is sustained. In conclusion, multicropping practice should be encouraged as it provides several benefits to the community resilience, the soil and various organisms that dwell on and in it, the crop species, income, the environment, biodiversity and also varieties of foodstuff which provide the needed dietary food calories in the community.

Fructans Prime ROS Dynamics and Botrytis cinerea Resistance in Arabidopsis.

Naturally derived molecules can be used as priming or defense stimulatory agents to protect against biotic stress. Fructans have gained strong interest due to their ability to induce resistance in a number of crop species. In this study, we set out to establish the role of fructan-induced immunity against the fungal pathogen Botrytis cinerea in Arabidopsis thaliana. We show that both inulin- and levan-type fructans from different sources can enhance Arabidopsis resistance against B. cinerea. We found that inulin from chicory roots and levan oligosaccharides from the exopolysaccharide-producing bacterium Halomonas smyrnensis primed the NADPH-oxidase-mediated reactive oxygen species (ROS) burst in response to the elicitors flg22, derived from the bacterial flagellum, and oligogalacturonides (OGs), derived from the host cell wall. Neither induced a direct ROS burst typical of elicitors. We also found a primed response after infection with B. cinerea for H2O2 accumulation and the activities of ascorbate peroxidase and catalase. Sucrose accumulated as a consequence of fructan priming, and glucose and sucrose levels increased in fructan-treated plants after infection with B. cinerea. This study shows that levan-type fructans, specifically from bacterial origin, can prime plant defenses and that both inulin and levan oligosaccharide-mediated priming is associated with changes in ROS dynamics and sugar metabolism. Establishing fructan-induced immunity in Arabidopsis is an important step to further study the underlying mechanisms since a broad range of biological resources are available for Arabidopsis.

Nocturnal bird composition in relation to habitat heterogeneity in small scale oil palm agriculture in Malaysia

The expansion of oil palm cultivation is recognised as a major cause of tropical biodiversity loss. In contrast to large-scale plantations, oil palm smallholdings being more heterogeneous may support greater biodiversity. This study examined the effects of local and landscape level variables on the composition of nocturnal bird species in Malaysian oil palm smallholdings. Using visual and aural point sampling, we made 1408 encounters with nine owl and two nightjar species. The Biota-Environment-Stepwise matching analyses (BEST) indicated four predictor variables (three local variables; number of crop species, widths of roads and trenches, and one landscape variable; distance to the nearest main road) significantly influenced the community assemblages of nocturnal bird species in the smallholdings. Generalized Linear Models (GLMs) further indicated seven predictor variables (numbers of palms and houses, widths of roads and trenches, distances to the nearest forest and house, as well as palm height) significantly influenced the abundances of certain nocturnal species. These findings not only improve our understanding on habitat preference of nocturnal birds in the Sunda region but also support the argument that habitat complexity in cultivated areas may aid in biodiversity conservation, at least for nocturnal birds.

On-farm conservation of 12 cereal crops among 15 ethnic groups in Yunnan (PR China)

Due to the rapid diffusion of improved crop varieties, fewer and fewer landraces are being grown by farmers. The on-farm conservation of crop landraces has been proposed as means of conserving potentially important crop germplasm as an alternative to its ex situ conservation in gene banks, but the effectiveness of this approach is unproven. Particular attention is currently focused on producers sited in remote regions. Here, we report the outcomes of a survey focusing on the conservation and utilization of landraces of corn, rice, wheat, barley, buckwheat, broomcorn sorghum, Job’s tears (coix), oats and finger, foxtail, broomcorn and barnyard millets grown by 15 ethnic groups from Yunnan province (China). Many local varieties are still in existence through their utilization on-farm. The varietal richness per village sampled was estimated to be 3.5 (maximum of 17), with rice and maize being the most heterogeneous, and glutinous sorghum and barnyard millet the least. Varietal richness was significantly and positively correlated with the number of villages surveyed, the number of families and the head of population. The choice of crops and varieties maintained varied between the ethnic groups, with the more westerly and north westerly situated villages conserving the most landraces. The number of crop species used was negatively correlated with per capita annual income, while the correlation coefficient between varietal richness and per capita annual income was less pronounced. The major factors determining the level of on-farm conservation were remoteness, fragmentation of the arable area and cultural needs. The data provide baseline information for the elaboration of optimal strategies for in situ conservation and utilization of crop germplasm in China.

Hybrid Rice Breeding Welcomes a New Era of Molecular Crop Design

Heterosis, or hybrid vigor, is a general phenomenon in biology. Harvest of heterosis has been succeeded in a number of crop species. Hybrid rice was first adapted in China in large scale in the middle of 1970s, and two generations of hybrid seed production technology based on distinct male sterility mutations have been employed. New hybrid seed production systems have been reported lately using the modern biotechnology and molecular crop design, which may lead to a new era of hybrid rice practice.

Doubled Haploids versus Conventional Breeding in CIMMYT Wheat Breeding Programs

Doubled haploid (DH) technology has been used in breeding programs for several decades and is currently the method of choice in a number of crop species, including barley (Hordeum vulgare L.), rapeseed (Brassica napus L.), maize (Zea mays L.), and wheat (Triticum aestivum L.). In this study we investigated via computer simulation the benefit of using DHs compared with the conventional wheat breeding strategy used at CIMMYT. Two strategies using DHs were considered: DH lines directly derived from F1 hybrids (F1–DH), and DH lines derived from F3 individuals that are retained following selection for agronomic traits in the F2 generation (F3–DH). Genetic gains per cycle, per year, and per dollar spent were consistently higher for conventional breeding than for DH breeding strategies, especially gains per dollar. Though the F1–DH strategy saved 1 yr in completing a breeding cycle, genetic gains per year for the adaptation trait from F1–DH were much lower than those from conventional breeding, where two growing seasons are used per year. Though the DH breeding strategy showed no significant advantages over the conventional wheat shuttle‐breeding regime of CIMMYT, we did not exclude the possibility that the DH breeding strategy may have advantages when genetic gains per unit of time are considered, and only one generation is grown per year. The conventional shuttle regime will continue to be the major wheat breeding strategy at CIMMYT, where two cycles can be grown per year and breeders can do selection in large populations in both cycles.

Controlling annual weeds in cereals by deploying crop rotation at the landscape scale: Avena sterilis as an example

Weed control through crop rotation has mainly been studied in a nonspatial context. However, weed seeds are often spread beyond the crop field by a variety of vectors. For weed control to be successful, weed management should thus be evaluated at the landscape level. In this paper we assess how seed dispersal affects the interactions between crop rotation and landscape heterogeneity schemes with regard to weed control. A spatially explicit landscape model was developed to study both short- and long-term weed population dynamics under different management scenarios. We allowed for both two- and three-crop species rotations and three levels of between-field weed seed dispersal. All rotation scenarios and seed dispersal fractions were analyzed for both completely homogeneous landscapes and heterogeneous landscapes in which more than one crop was present. The potential of implementing new weed control methods was also analyzed. The model results suggest that, like crop rotation at the field level, crop rotation implemented at the landscape level has great potential to control weeds, whereby both the number of crop species and the cropping sequence within the crop rotation have significant effects on both the short- and long-term weed population densities. In the absence of seed dispersal, weed populations became extinct when the fraction of each crop in the landscape was randomized. In general, weed seed densities increased in landscapes with increasing similarity in crop proportions, but in these landscapes the level of seed dispersal affected which three-crop species rotation sequence was most efficient at controlling the weed densities. We show that ignoring seed dispersal between fields might lead to the selection of suboptimal tactics and that homogeneous crop field patches that follow a specific crop rotation sequence might be the most sustainable method of weed control. Effective weed control through crop rotation thus requires coordination between farmers with regard to cropping sequences, crop allocation across the landscape, and/ or the fraction of each crop across the landscape.

Gene flow between crops and their wild relatives

Gene flow between crops and their wild relatives

Shotguns and SNPs: how fast and cheap sequencing is revolutionizing plant biology

In 1998 Cereon Genomics LLC, a subsidiary of Monsanto Co., performed a shotgun sequencing of the Arabidopsis thaliana Landsberg erecta genome to a depth of twofold coverage using 'classic' Sanger sequencing. This sequence was assembled and aligned to the Columbia ecotype sequence produced by the Arabidopsis Genome Initiative. The analysis provided tens of thousands of high-confidence predictions of polymorphisms between these two varieties of A. thaliana, and the predicted polymorphisms and Landsberg erecta sequence were subsequently made available to the not-for-profit research community by Monsanto. These data have been used for a wide variety of published studies, including map-based gene identification from forward genetic screens, studies of recombination and organelle genetics, and gene expression studies. The combination of resequencing approaches with next-generation sequencing technology has led to an increasing number of similar studies of genome-wide genetic diversity in A. thaliana, including the 1001 genomes project (http://1001genomes.org). Similar approaches are becoming possible in any number of crop species as DNA sequencing costs plummet and throughput rapidly increases, promising to lay the groundwork for revolutionizing our understanding of the relationship between genotype and phenotype in plants.

Interactive effects of HIV/AIDS and household headship determine home garden diversity in the Eastern Region of Ghana

Home gardens are important for enhancing food and nutritional security for HIV/AIDS-afflicted rural households through dietary diversity. Female-headed households may depend on home gardens more than average households to supply and supplement the household's diet when labour is constrained for field cropping. This paper compares household characteristics, dietary diversity, labour allocated to crop husbandry and home garden biodiversity amongst 22 HIV/AIDS-afflicted female-headed households, 15 non-HIV/AIDS-afflicted female-headed, 10 HIV/AIDS-afflicted dual-headed and 33 non-HIV/AIDS-afflicted dual-headed households in rural communities in the Eastern Region of Ghana. Information on household characteristics and labour allocation to home garden management was obtained through a cross-sectional survey and in-depth interviews. Dietary diversity score was estimated for each household based on a 24-hour qualitative dietary recall. Plant species in each home garden were recorded. HIV/ AIDS affliction did not affect home garden diversity but afflicted households had more on-farm sources of income and a higher dietary diversity and allocated more adult labour to home garden activities than non-afflicted households. Dual-headed households had more diversity in the home garden and allocated more adult male labour to the home garden than female-headed households. Statistically significant interactions between HIV/AIDS affliction and headship were observed for Shannon-Wiener index, number of crop species, number of annual crop species and number of root and tuber crop species in the home gardens: there were no headship effects when households were afflicted whereas dual-headed households had higher values than female-headed households in non-afflicted households. HIV/AIDS-afflicted households had significantly more annual crop species and more root and tuber crop species than non-afflicted households for female-headed households, whereas there were no significant differences for dual-headed households. Faced with confinement to the homestead in caregiving and by the obligation to ensure household food and nutritional security, HIV/AIDS-afflicted households spent more (female] labour on home garden management than non-afflicted households to produce crops for sustenance and dietary diversity.

Effects of defoliating insect resistance QTLs and a cry1Ac transgene in soybean near-isogenic lines

The crystal proteins coded by transgenes from Bacillus thuringiensis (Bt) have shown considerable value in providing effective insect resistance in a number of crop species, including soybean, Glycine max (L.) Merr. Additional sources of soybean insect resistance would be desirable to manage the development of tolerance/resistance to crystal proteins by defoliating insects and to sustain the deployment of Bt crops. The objective of this study was to evaluate the effects and interactions of three insect resistance quantitative trait loci (QTLs; QTL-M, QTL-H, and QTL-G) originating from Japanese soybean PI 229358 and a cry1Ac gene in a "Benning" genetic background. A set of 16 BC(6)F(2)-derived near isogenic lines (NILs) was developed using marker-assisted backcrosses and evaluated for resistance to soybean looper [SBL, Pseudoplusia includens (Walker)] and corn earworm [CEW, Helicoverpa zea (Boddie)] in field cage, greenhouse, and detached leaf assays. Both Bt and QTL-M had significantly reduced defoliation by both SBL and CEW and reduced larval weight of CEW. The antibiosis QTL-G had a significant effect on reducing CEW larval weight and also a significant effect on reducing defoliation by SBL and CEW in some assays. The antixenosis QTL-H had no main effect, but it appeared to function through interaction with QTL-M and QTL-G. Adding QTL-H and QTL-G further enhanced the resistance of the Bt and QTL-M combination to CEW in the field cage assay. These results should help guide the development of strategies for effective management of insect pests and for sustainable deployment of Bt genes.

Relationships between crop-species diversity and soil characteristics in southwest Indian agroecosystems

In humid tropical agroecosystems, maintenance of soil fertility is critical to sustainability, yet inputs of fossil-fuel fertilizer are beyond the economic means of many farmers. One economically viable alternative is to manage soil organic matter (SOM) dynamics by altering the composition and number of crop species. The objectives of this study were to determine long-term effects of crop-species composition and richness on indices of soil fertility, in comparison with forests, and to evaluate mechanisms of crop-species influence. Study plots were established in the diverse array of agroecosystems in Kerala, India, where agriculture has been documented for >4000 year. With 91 different crops in the region, analyses were simplified by categorizing crops by functional groups, based on life form, nutrient cycling traits, and phenology. Mono-, bi- and polycultures contained 1, 2 and >2 functional groups, respectively. A paired-plot design in which a monoculture or biculture was paired with a polyculture within a farm was used, such that climate, soil, ownership, and management were as similar as possible for a pair. Soil properties (total soil organic carbon (SOC), N, pH, bulk density) and crop structural attributes that had the potential to influence SOC stocks (basal area and frequency) were measured in 100 m 2 plots ( n=70 pairs) within 50 farms. Three plots in nearby forests provided a basis for comparison. Total SOC ranged from 6 to 20 g kg −1 (in coastal areas and uplands, respectively), compared to 34–60 g kg −1 in nearby upland forests. Differences in total SOC between mono- and polycultures depended on identity of the functional group in the monoculture: SOC amounts were higher in polycultures if the monoculture in comparison was a palm ( P=0.02) or herbaceous annual ( P=0.001), but not if the monoculture was a deciduous tree. Total SOC was 61% lower in polycultures cultivated for 40–60 years than in nearby forests. Under some conditions, total SOC increased directly with basal area (BA), an index of shading, indicating that BA may be an important design element of agroecosystems. Modeling results indicated that differences in lignin content of crop inputs could influence SOM quantity and quality; hence, crop tissue-chemistry traits may also be important elements of design. These results from ancient, humid tropical agroecosystems suggest that for maintenance of long-term soil fertility, high species richness may not be as important as individual species traits that influence nutrient cycling.

Plant breeding in the turn of the millennium

The transition from hunting and gathering to farming happened about 10,000 years ago, independently and diffusely in several places in the world. Plant breeders were responsible for genetic progress in a number of crop species. It included hybrids, the introgression of wild species genes and also the Green Revolution, which started in the 1960's with the cereals. The varieties developed by breeding, along with the use of new crop technology (fertilization, soil tillage, etc.) changed the status of some countries from importers to exporters of food. In the turn of the millennium,, plant breeding, faces new challenges in a globalized world, but it has new tools to deal with them. Notwithstanding the present contributions of plant breeding and crop management, its future contributions may be even greater. The partnership being developed between plant breeding and biotechnology will assure a more consistent and predictable genetic progress. Current contributions of biotechnology have arrived for many crops in different places of the world. Varieties developed by transformation are grown in large acreage in some countries. Some concerns have also arisen from the use of GMOs. For example, the introgression of a gene for insect resistance 4 into many different species could result in an undesirable endemic risk, here called interespecific biotechnological vulnerability. Another concern is that biotechnology race may create yield plateaus in programs using genes pyramiding for all new traits made available by biotechnology, resulting in what is called genetic gridlock. Nevertheless, the benefits of using biotechnology will substantially enhance the contributions of plant breeding to human life

The Phloem Mobility of Boron Alters Symptom Expression and Management of Boron in Plants

We have demonstrated that boron (B) is freely phloem mobile in a number of crop species and we predict that B will be mobile in all species that transport polyols (mannitol, sorbitol, dulcitol). This finding directly contradicts accepted dogma and profoundly influences the diagnosis and management of B in almond, apple, apricot, cherry, pear, peach, plum, prune, celery, and other species. In the majority plants, B moves in the xylem with the transpiration stream. Once B enters the leaf, it remains there with little or no redistribution. As a result, there is always a decreasing concentration gradient of B from old to young leaves and B toxicity symptoms always occurs in the old leaves first, typically exhibiting tip and margin burn. In species in which B is mobile, these symptoms do not occur. When almond, peach, and plum were exposed to high B in the growth medium, the predominant site of B accumulation was fruit, young stems and apical meristems. As a consequence, the earliest symptoms of B toxicity in species in which B is phloem mobile are observed in the young shoot meristems and fruits. Foliar application of 10B isotope demonstrates that B is readily transported to neighboring fruits and buds of almond, apple, and nectarine. In apple seedlings, plant B requirements can be fully satisfied solely by foliar application to a few mature leaves. This strongly suggest that foliar B applications can be used as an efficient means for B fertilization in Malus, Prunus, and Pyrus species. Details of the studies and their implications for B management will be discussed.

In vitro Techniques and Plant Morphogenesis: Fundamental Aspects and Practical Applications.

Plant cell and tissue culture together with the recent advances in recombinant DNA technology are getting great attention because these are the sources of innovation for the major agricultural industries and practice. However, despite the many successful applications of plant tissue culture in agriculture and horticulture, differentiation and especially plant regeneration, remain a major problem with a number of crop species. Relatively few crop species are capable of predictable regeneration. Even in those instances where regeneration has been reported, e. g. Nicotiana, Petunia and Arabidopsis, through empirical selection of explants and media, problems are often encountered with particular cultivars within a species. Hence, these problems constitute a serious block to crop improvement. Moreover, a detailed characterization of the competent host plant cell will be required if we are to further exploit the Agrobacterium system for transformation of recalcitrant plant species. In this review article we describe some possible opportunities which may lead to rational plant improvement.

Research Plot Planter with Wide Versatility1

AbstractField research with small grains or row crops often involves a number of different treatments at planting. Since no presently available, or previously described, individual planter provides all the flexibility needed for a wide range of experiments, a planting unit was constructed that permits simple changes in species, cultivars, seeding rates, row spacing, and fertilizer rates and materials. The three‐point hitch mounted unit consists of a steel framework with seven double disk coulters, two fertilizer boxes, a cone‐spinner and distributor, and an operator's seat. The planter can be adjusted to plant plots ranging from 1 to 75‐m long at any seeding rate and with row spacings of 16, 36, 54, and 72 cm. Fertilizer rates of 20 to 800 kg/ha can be applied through each box. A number of crop species, including forages, have been successfully planted with the machine over the past 2 years. The unit is easily transported and can plant as many as 100 8‐m long plots/hour.

Fully Automatic Subirrigation System for Glasshouse and Growth Chamber Use1

A fully automatic subirrigation system is described for use in the glasshouse or environmental control chambers. Versatility in watering schedules, rooting mediums, and potting containers is provided. A number of crop species have been successfully grown using this system.