Our previous studies indicated that ditch-buried straw return (DB-SR) can improve soil processes in the short term, i.e. increasing microbial metabolic capability, reducing nitrogen leaching loss and promoting soil aggregation. However, it remains unclear how long-term implementation of DB-SR affects soil carbon (C) and nitrogen (N) processes and crop yields. Here, the effects of DB-SR on soil C pool and N availability as well as grain yields were investigated after consecutive application of 6 (rice season) and 6.5 years (wheat season). We found that long-term DB-SR significantly increased rice yields, total organic C, NH₄⁺ and NO₃^– in the rice soils, as well as enhanced wheat yields, microbial biomass C, microbial biomass N, microbial biomass C/total organic C ratio and microbial biomass C/N ratio, but reduced NH₄⁺ and NO₃^– in the wheat soils when compared with rotary tillage straw return (RT-SR) and no tillage with straw removal (NT-NS). These findings suggest that long-term DB-SR application has positive effects on grain production, but possibly through different mechanisms in improving soil processes. The yield-increasing effects on rice might result from improvements in soil fertility, whereas increased wheat yields can be ascribed to stimulated soil microbial activity.

Salinity-alkalinity stress is one of the main factors limiting crop growth and production. However, few genetic sources that can be used to improve soybean salinity-alkalinity tolerance are available. The objective of this study was to determine the genetic mechanisms for salinity-alkalinity tolerance in soybean during germination by a genome-wide association study (GWAS) using 281 accessions with 58 112 single nucleotide polymorphisms (SNPs). Four salinity-alkalinity tolerance (ST) indices namely ST-GR (germination ratio), ST-RFW (root fresh weight), ST-DRW (root dry weight), and ST-RL (root length) were used to assess soybean salinity-alkalinity tolerance. A total of 8, 4, 6, and 4 quantitative trait loci (QTL) accounted for 3.83–8.01% phenotypic variation in ST-GR, ST-RL, ST-RFW, and ST-RDW, respectively. Two common QTL (qST.5.1 and qST.16.1) associated with at least three indices located on chromosome 5 (∼38.4 Mb) and chromosome 16 (∼29.8 Mb), were determined as important loci for controlling salinity-alkalinity tolerance in soybean. We also predicted candidate genes for the two QTL. The significant SNPs and common QTL as well as the salinity-alkalinity tolerant accessions will improve the efficiency of marker-assisted breeding and candidate gene discovery for soybean salinity-alkalinity tolerance.

Sugarcane (Saccharum hybrid) is an important industrial crop worldwide. Its growth and sucrose contents are severely affected by drought stress. Genetic engineering offers a rapid solution to improve tolerance level of sugarcane against this stress. This study was designed to transform sugarcane with the Tomato ethylene responsive factor 1 (TERF1) gene through Agrobacterium. Embryogenic callus of sugarcane cv. XintaitangR22 was used for transformation with Agrobacterium strain LBA4404 harbouring the pROK2 vector containing the TERF1 gene driven by the CaMV 35S promoter. Highest regeneration efficiency (74%) was obtained with inoculum density (OD₆₀₀) at 0.4 and co-cultivated for 4 days on MS-based medium; 5.4% transformation efficiency was acquired from the regenerated plants. Successful insertion of the TERF1 gene into sugarcane was indicated by PCR-positive plants (n = 4). Expression of TERF1 transcripts in transgenic lines at various levels was detected by reverse transcriptase-PCR. Under normal conditions, growth status of transgenic lines was similar to that of wild-type plants; by contrast, only transgenic lines were able to withstand water-deficit stress conditions, showing tolerance against drought stress. Physiological and biochemical assays revealed that TERF1-overexpressed plants showed not only increased accumulation of proline, soluble sugars and glycine betaine but also reduced malondialdehyde and H₂O₂ content in response to drought stress. Our results revealed that overexpression of TERF1 in sugarcane conferred drought tolerance through increased accumulation of osmo-protectant, decreasing reactive oxygen species and malondialdehyde content, which possibly resulted from activation of expression of stress-related genes by TERF1 under stress. These findings indicate that the gene might have a regulatory role in the response to drought stress in sugarcane.

Improvement of tomato (Lycopersicon esculentum L.) for growth in saline soils is a major goal of tomato breeders. The aim of this study was to identify the genetic combining ability and genetics of salinity tolerance in tomato. Plant materials were grown under normal (NG) and salinity stress (SSG) conditions. Results showed that the genetic controlling mechanism of salinity-related traits and fruit weight is complex and that all genetic components of additive, non-additive and maternal are involved. The nature of gene action for fruit weight and salinity-related traits was significantly affected by salinity stress. Dominance and additive gene action were predominant under NG and SSG, respectively. Under NG, the best general combiner parent for fruit weight was P3 (salt-tolerant with moderate fruit yield). Under SSG, P1 (highly salt-tolerant with low fruit yield) was the best general combiner parent for fruit weight and exhibited high genetic combining ability for K⁺/Na⁺, lipoxygenase activity, proline, relative water content, total carbohydrate and cell membrane stability. With the high frequency of genes effective in salt tolerance, the P1 parent appeared as the best specific mating partner with other parents under SSG. Simultaneous selection for fruit weight and surrogate traits (cell membrane stability, proline and relative water content) in a population derived from the P1 × P5 (susceptible with high fruit yield) cross could result in a salt-tolerant tomato genotype.

Analysis of potential areas for crop establishment is necessary for sustainable agricultural planning, conservation of natural ecosystems, and achievement of food security’s current global objective. This study aims to model the current potential distribution of the optimal areas for Hass avocado crop in Mexico, along with the likely impact of climate change on the crops and the surrounding mountain ecosystems in the state of Michoacán, the principal producer. The maximum entropy approach was used to model the current and future potential distribution of the avocado using points of presence of avocado cultivation in Mexico and climatic variables under 10 global climate models (GCMs) and three representative concentration pathways (RCPs) from the IPCC. We estimated a current potential area for the establishment of Hass avocado crops in Mexico of 54 597 km², associated with the temperate forests of the Transversal Volcanic Belt and the Sierra Madre del Sur. The loss of area for the establishment of avocado crops in Mexico was 31.1% under the most optimistic scenario, RCP 2.6, whereas 43.0% would be lost under the most pessimistic scenario, RCP 8.5. Currently, the potential distribution for the establishment of Hass avocado crops in the state of Michoacán is 22 561 km². Given optimistic scenarios RCP 2.6 and RCP 8.5 of climate change by 2050, temperate forests mountain would represent 59 and 72.3%, respectively, of the potential area for establishing avocado in the state. Commercial pressure and climate change can lead to forest mountain ecosystem deforestation to establish new avocado crops and exacerbate water resource scarcity problems, jeopardising the entire production system’s sustainability. Territorial planning should prioritise conservation policies to avoid land-use change and establish strategies to maintain avocado crop sustainability in the long-term under climate change scenarios.

Drought stress has an adverse effect on crop production and food quality. Milk thistle (Silybum marianum L.) is an oil and medicinal crop known as an alternative oil crop with high level of unsaturated fatty acids, which makes it a favourable edible oil for use in food production. Silymarin (a mixture of flavonolignans) is the main active medicinal component. Biochemical diversity, changes induced by water deficit stress in secondary metabolites, and their relationships with production traits in native germplasm are poorly understood in milk thistle. Twenty-six ecotypes mainly collected from different regions of Iran were evaluated for oil, fatty acid profile, triacylglycerol (TAG) composition, silymarin and agro-morphological traits under non-stress and water stress conditions for 2 years. Water stress increased oil and silymarin content while decreasing fruit yield and related traits. The most abundant fatty acid averaged over all ecotypes under both moisture conditions was linoleic acid (L, 39%), followed by oleic acid (O, 36%), palmitic acid (P, 9%) and stearic acid (E, 6%). Among the 24 detected TAGs, the five major compositions were OOL, OLL + OOLn (linolenic), POL, OOO, LLL + OLLn and EOL. Superior ecotypes rich in monounsaturated and polyunsaturated fatty acids were identified and can be introduced as candidates for food, medicinal and industrial purposes. Associations among different attributes are discussed.

In order to investigate the potential for domestication of native pasture legumes, a seed collecting mission was undertaken between Kalbarri and Esperance in the south of Western Australia followed by establishment of a field nursery at Northam, Western Australia. Indigofera australis subsp. hesperia Peter G.Wilson & Rowe was collected from eight sites, Indigofera brevidens Benth. from one site, and Glycyrrhiza acanthocarpa (Lindl.) J.M.Black from six sites. The field nursery was an irrigated, replicated trial designed to produce seed for future field testing and to provide preliminary information on plant agronomic characteristics. Over 12 months, I. australis produced herbage dry matter (DM) of 2.1–4.4 t/ha compared with 3.4 t/ha for a composite line of tedera (Bituminaria bituminosa C.H. Stirton vars. albomarginata and crassiuscula) and 1.0 t/ha DM for G. acanthocarpa. Most lines had digestibility and crude protein (15–25%) values that would support moderate growth of sheep or cattle. The best line of G. acanthocarpa produced >400 kg/ha of seeds, whereas I. australis had poor production most likely due to poor adaptation to the nursery site. The severity of cutting of I. australis plants had no significant effect on visual assessments of herbage growth. Most plants of I. australis died within 3 years, whereas most plants of G. acanthocarpa, I. brevidens and tedera survived for 3 years. Both I. australis and G. acanthocarpa have potential for use in broadacre agriculture as grazing plants, most likely in niches specifically suited to each, and demonstrate that native plants can contribute to pasture production currently dominated by exotic species.