Modeling Basin-Scale Impacts of Cultivation Practices on Cotton Yield and Water Conservation under Various Hydroclimatic Regimes

The SWAT model equipped with an improved auto-irrigation function was used to assess the impacts of cultivation practices on irrigated and dryland cotton yield and water conservation in the Texas Panhandle. Results showed the largest irrigation depth led to reductions in irrigation and crop evapotranspiration (ETc) with slightly increased cotton yields compared to the baseline scenarios under different hydroclimatic regimes. However, soil water content and surface runoff values were increased when using the largest irrigation depth. The opposite results were observed for the small irrigation depth. Early planting of cotton resulted in decreased irrigation and ETc, and increased cotton yields under both irrigated and dryland conditions, particularly in normal and wet years. By contrast, the late planting scenarios indicated the opposite for those variables. Simulated hydrologic variables were relatively stable using various maturity cultivars. Nevertheless, greater than 10% reductions in irrigated cotton yield under diverse hydroclimatic years and dryland yields during normal and wet years were identified in the long-season cotton. The opposite was determined for the short-season cotton. These outcomes suggest that a larger irrigation depth, earlier planting date, and short-season cultivar are promising cultivation practices for improving cotton yield and water conservation in the Texas Panhandle.

Early Relay Intercropping of Short-Season Cotton Increases Lint Yield and Earliness by Improving the Yield Components and Boll Distribution under Wheat-Cotton Double Cropping

Wheat-cotton double cropping has improved crop productivity and economic benefits per unit land area in many countries, including China. However, relay intercropping of full-season cotton and wheat, the most commonly adopted mode, is labor-intensive and unconducive to mechanization. The direct sowing of short-season cotton after wheat (CAW) has been successful, but cotton yields and economic benefits are greatly reduced. Whether the relay intercropping of short-season cotton before the wheat harvest increases cotton yields remains unclear, as does the earliness and fiber quality relative to those for CAW. Therefore, we directly planted short-season cotton after wheat harvest on 15 June (CAW) as the control and interplanted short-season cotton in wheat on 15 May (S1), 25 May (S2) and 5 June (S3), which were 30, 20 and 10 days prior to wheat harvest, respectively, from 2016 to 2018. The crop growth, yield, yield components, boll distribution, and earliness of the cotton were evaluated. The yields and earliness of short-season cotton under relay intercropping were 26.7–30.6% and 20.4–42.9% higher than those under CAW, respectively. Compared with CAW, relay intercropping treatments increased the boll density, boll weight and lint percentage by 5.6–13.1%, 12.5–24.5% and 5.8–12.7%, respectively. The dry matter accumulation and harvest index under the relay intercropping treatments were also greater than those under CAW, which might be attributed to the greater partitioning of dry matter to the seed cotton than to the boll shells. Among the relay intercropping treatments (S1, S2 and S3), the lint yield did not differ, but S1 and S2 were considerably better than S3 based on earliness and fiber quality. The analysis of the within-plant spatial boll distribution showed that more bolls were formed on the lower to middle fruiting branches and at the first fruiting sites for S1 and S2 than for S3 and CAW. Therefore, the increased earliness and fiber quality induced through early relay intercropping (S1 and S2) could be attributed to an improved spatial boll distribution compared to late relay intercropping (S3) or CAW. Conclusively, compared to late relay intercropping and CAW, early relay intercropping considerably increased the lint yield, fiber quality, and earliness by improving the yield components, boll distribution, and dry matter accumulation and partitioning. The relay intercropping of short-season cotton 20 to 30 days before wheat harvest represents a promising alternative to CAW in wheat-cotton double-cropping systems in the Yellow River Basin of China and other regions with similar conditions.

The yield of legume-gramineous ecosystems with various varieties of red clover on the Non-Chernozem drained lands

Изучение урожайности трёхкомпонентных бобово-злаковых травосмесей с различными сортами клевера лугового проводилось в Тверской области на опытном поле ВНИИ мелиорированных земель в 2018–2020 годах. Опыт заложен в 2018 году на осушаемой дерново-подзолистой почве. Изучались следующие сорта многолетних трав: клевер луговой (Trifolium pratense L.) Кретуновский, Грин, Шанс, Фаленский 86; люцерна изменчивая (× Medicago varia Mart.) Вега 87; тимофеевка луговая (Phleum pratense L.) ВИК 9 и овсяница луговая (Festuca pratensis L.) Сахаровская. В 2020 году наиболее высокими темпами роста обладали травостои второго года пользования с ранними сортами клевера лугового Кретуновский и Грин в смеси с тимофеевкой луговой сорта ВИК 9 — 67–70 см при густоте стеблестоя 495–852 шт./м2. Наиболее продуктивными на осушаемых землях показали себя смешанные травостои люцерны изменчивой, клевера лугового и тимофеевки луговой. Трёхкомпонентные агрофитоценозы укосного типа на основе сортов клевера лугового Кретуновский, Грин, Шанс, Фаленский 86, люцерны изменчивой и тимофеевки луговой сформировали урожай кормовой массы 35–39,7 т/га. Травосмесь тимофеевки луговой с раннеспелым сортом клевера Шанс сформировала два укоса с выходом сухой массы 9,5 т/га, овсяницы луговой — 9,0 т/га. Отмечено хорошее качество полученной растительной массы: содержание переваримого протеина составило 18,9–19,5 г/кг при энергетической питательности 1,09–1,26. В растительной массе травосмесей с овсяницей луговой содержание переваримого протеина было выше, чем в смесях с тимофеевкой луговой, на 1,1 г/кг корма в первом и на 2,41 г/кг корма во втором укосе. По содержанию кормовых единиц в 1 кг корма питательность кормовой массы в зависимости от состава исследуемых смесей была равноценна — 0,23–0,24. The investigation took place in the Tver region on the trial field of the All-Russian Research Institute of Reclaimed Lands in 2018–2020. The research tested the yield of trinary legume-gramineous ecosystems with various varieties of red clover. The field trial was carried out on the drained sod-podzolic soil in 2018. The following perennial grasses were studied: red clover (Trifolium pratense L.) “Kretunovskiy”, “Grin”, “Shans”, “Falenskiy 86”; bastard alfalfa (× Medicago varia Mart.) “Vega 87”; common timothy (Phleum pratense L.) “VIK 9”; and meadow fescue (Festuca pratensis L.) “Sakharovskaya”. Growth rates were the highest in the mixtures with short-season red clover varieties “Kretunovskiy”, “Grin”, and common timothy. In 2020, these variants reached height of 67–70 cm and density of 495–852 plants per m2 in the second year. Trinary ecosystems to be cut with bastard alfalfa, red clover “Kretunovskiy”, “Grin”, “Shans”, “Falenskiy 86”, and common timothy provided the maximum yield on the drained lands — 35–39.7 t ha-1. The mixture of common timothy with short-season red clover “Shans” formed 9.5 t ha-1 of dry mass per two cuts, meadow fescue — 9.0 t ha-1. The feed mass showed high quality: digestible protein content was 18.9–19.5 g/kg, energy nutrition was 1.09–1.26. Mixtures with meadow fescue exceeded the ones with common timothy in digestible protein content by 1.1 g/kg in the first cut and by 2.41 g/kg — in the second one. Different variants showed almost no variation in feed units per 1 kg of forage — 0.23–0.24.

Genomic basis of parallel adaptation varies with divergence in Arabidopsis and its relatives

Parallel adaptation provides valuable insight into the predictability of evolutionary change through replicated natural experiments. A steadily increasing number of studies have demonstrated genomic parallelism, yet the magnitude of this parallelism varies depending on whether populations, species, or genera are compared. This led us to hypothesize that the magnitude of genomic parallelism scales with genetic divergence between lineages, but whether this is the case and the underlying evolutionary processes remain unknown. Here, we resequenced seven parallel lineages of two Arabidopsis species, which repeatedly adapted to challenging alpine environments. By combining genome-wide divergence scans with model-based approaches, we detected a suite of 151 genes that show parallel signatures of positive selection associated with alpine colonization, involved in response to cold, high radiation, short season, herbivores, and pathogens. We complemented these parallel candidates with published gene lists from five additional alpine Brassicaceae and tested our hypothesis on a broad scale spanning ∼0.02 to 18 My of divergence. Indeed, we found quantitatively variable genomic parallelism whose extent significantly decreased with increasing divergence between the compared lineages. We further modeled parallel evolution over the Arabidopsis candidate genes and showed that a decreasing probability of repeated selection on the same standing or introgressed alleles drives the observed pattern of divergence-dependent parallelism. We therefore conclude that genetic divergence between populations, species, and genera, affecting the pool of shared variants, is an important factor in the predictability of genome evolution.