Biomass production of Lolio‐Cynosuretum grassland is not increased by plant‐species richness

In experimental grasslands, a positive relationship between biomass production and plant diversity has often been found. Here, we compared a moderately species‐rich old sward with its grass‐dominated counterpart (12 vs. 8 species per 2.5 m², or 8.3 vs. 0.7% yield proportion of dicots at the start of the experiment) established by herbicide application. We hypothesized an increased N, P and K uptake in the diverse sward related to a higher colonization rate with arbuscular mycorrhizal fungi (AMF), the presence of legumes, and complementary nutrient use of plant species. Phosphorus or N fertilizer application (according to contributions of AMF or legumes) were expected to balance the assumed smaller biomass production of the grass compared to the diverse sward. In two experimental years, N, P and K uptake, biomass production, N₂ fixation, and intra‐ and extraradical AMF colonization were investigated in an untreated control and plots that were fertilized with P and N in a low (P1: 20 kg P ha^?1; N1: 50 kg N ha^?1) or a high dose (P2: 100 kg P ha^?1; N2: 500 kg N ha^?1) in both swards. Biomass production was larger in the grass compared to the diverse sward. The N, P and K uptake, accumulated over three harvests (or 1.5 years), was also larger in the grass sward. The biomass production ranged from 5.3 to 10.0 t ha^?1 and accumulated nutrient uptake from 82 to191 kg N ha^?1, 19 to 31 kg P ha^?1 and 112 to 221 kg K ha^?1. Small legume proportions resulted in an accumulated N₂ fixation between 0 and 3 kg ha^?1. In the second year, the root length colonized with AMF structures was larger in the diverse compared to the grass sward, and the root length colonized with arbuscules and coils was larger in the N2 treatment compared to the control in the diverse sward. There were hints to higher AMF abundance under conditions of limited P availability (low soil P content, high N:P ratio in plant biomass). We conclude that in semi‐natural grassland of moderate species richness several factors may affect the relationship between plant diversity and productivity, i.e., management, plant species identity, and the number of the plant species of the low‐diversity level.     

Yield Response of Intercropped Soybean and Maize Under Rhizobia (Bradyrhizobium japonicum) Inoculation and P and K Fertilization

A 2-year trial was carried out at the Tanzania Coffee Research Institute (TaCRI) farm in northern Tanzania. The aim was to assess the response of soybean and maize yield attributes to cropping systems, rhizobia inoculation, and phosphorus (P) and potassium (K) fertilization. The study was laid out in a split-split plot design replicated thrice. The statistical analyses were performed using the 3-way analysis of variance in a factorial arrangement. The computation was performed using the STATISTICA software. The Fisher’s least significant difference (LSD) was used to compare the treatment means at p = 0.05 level of significance. The results showed that both cropping systems, rhizobia inoculation, and P and K fertilization significantly (p = 0.05) influenced most of the soybean yield parameters assessed in this study. Specifically, cropping systems significantly (p = 0.05) improved the number of pods per plant, biological yield, grain yield, and harvest index (HI) (2015 and 2016) of soybean. Rhizobia inoculation also significantly (p = 0.05) improved soybean yield attributes such as the number of pods, 100 seed weight, biological yield and grain yield of soybean (2015 and 2016), and HI in soybean (2015). P and K fertilization also significantly (p = 0.05) improved different yield attributes of soybean over the control. It was noted that increasing potassium from 20 to 40 kg/ha improved most of the soybean yield parameters relative to the control. Doubling of P from 26 kg to 52 kg/ha did not significantly change the soybean yield parameter. The doubled combined fertilizers did not significantly increase the yield parameters of soybean suggesting the use of a lower dose of combined fertilizers. Intercropping maize with rhizobia-inoculated soybean significantly improved maize yield compared with intercrop without inoculation. Monocropped maize gave relatively the same yield as those of maize intercropped with inoculated soybean. Fertilization with P and K also improved the yield attributes of maize over the control.     

Participatory farmers’ selection of common bean varieties (Phaseolus vulgaris L.) under different production constraints

On‐farm evaluation of 15 common bean varieties was undertaken with nine farmer groups under two fertilizer applications levels in four subcounties of Hoima and Rakai districts for two seasons to select farmers’ desired and undesired varieties. Farmers’ votes for acceptance and rejection of varieties at podding stage were converted to a preference index, and analysis of variance was conducted to examine differences in farmers’ preference indices among subcounties and combined across subcounties, seasons, management and gender. Management had no‐significant influence on the way farmers selected varieties in the subcounties. Choice of varieties varied significantly (p ≤ .001) between seasons and gender in the different subcounties. Variety Masindi Yellow Long and Farmers’ seed (Kaduli), and the introduced KATB1 were accepted by farmers due to their medium seed size, desired seed colour and potential of varietal adaptability to their farm conditions. Varieties NABE2, ROBA1 and RWR719 were deselected due to possession of traits less desired in the market. These results demonstrate the need for breeding programmes to involve diverse stakeholders in capturing the diverse traits preferences in varietal development process.     

Effects of tropical legume silages on intake,digestibility and performance in large and small ruminants: A review

A meta‐analysis was performed to determine the effects of feeding ruminants with tropical legume silages on intake, digestibility and performance using a data set with 218 treatments (162 containing legumes, 56 without legumes) from 62 trials. First, a regression analysis was performed for diets containing legumes. Dry‐matter intake (DMI) and digestibility decreased with increasing legume proportion, with greater effects on large compared with small ruminants. Milk yield (MY) by dairy cows was not affected by legumes. Average daily gain (ADG) by cattle was maximized with legume silage inclusion between 200 and 400 g/kg DM, but no effect appeared for small ruminants. A second analysis compared diets without legumes with diets with medium (101–400 g/kg DM) and high (401–800 g/kg DM) legume inclusion. There were no differences in DMI, MY and ADG between the medium inclusion and without legumes, but all these parameters decreased with high inclusion. Digestibility was lower in diets with legume silages than in diets without legumes, regardless of the inclusion level. Feed conversion efficiency (FCE) was highest in diets with medium inclusion and lowest with high legume inclusion. While high legume inclusion negatively affected performance, including legume silages up to 400 g/kg DM seems to enhance or at least maintain MY, ADG and FCE, despite lower intake and digestibility. The reasons for such apparent paradox remain unclear. Well‐designed studies focusing on, e.g. microbial protein synthesis, energy metabolism, protein/carbohydrates characteristics, are required to better understand the effects of tropical legumes silages on nutrients’ utilization.     

Bio‐agronomic characterization and implications on the potential use as forage of Bituminaria bituminosa and B. morisiana accessions

Perennial forage legumes may be pivotal for improving the sustainability of Mediterranean rainfed farming systems. This study summarizes the outcomes of a study aimed at characterizing morphological and agronomic traits of new germplasm of Bituminaria bituminosa and B. morisiana in Mediterranean environments. Five B. morisiana and three B. bituminosa native populations were evaluated in a small‐plot field experiment in Sardinia (Italy) and compared with seven Spanish accessions of B. bituminosa. The two Bituminaria species differed greatly in morphological traits and the beginning of the flowering stage, and remarkable variations between species were found for forage production and its seasonal distribution, seed yield and persistence. Average cumulative dry‐matter yield was higher in B. bituminosa than in B. morisiana (+7.6%; 297 vs. 276 g per plant). Average 3‐year seed production varied greatly between accessions (from 0.3 to 141 g per plant). Differences for these traits were also found between Sardinian and Spanish germplasm of B. bituminosa. Four clusters were generated by K‐means clustering. Accessions included in cluster III exhibited a positive combination of favourable forage production, high seed yield and satisfactory persistence. Nonetheless, the cluster analysis did not highlight a sharp discrimination between Bituminaria species. The overall results revealed the potential role of Sardinian accessions of B. bituminosa and B. morisiana in extending the forage season and for increased resilience of grasslands in Sardinia and other Mediterranean regions under rainfed conditions.     

Elevated carbon dioxide level along with phosphorus application and cyanobacterial inoculation enhances nitrogen fixation and uptake in cowpea crop

Climate change, as a result of increase in the concentration of greenhouse gases, influences growth and productivity of leguminous crops. A study was carried out to analyse the impacts of elevated carbon dioxide (CO₂) and cyanobacterial inoculation on growth, N₂ fixation and N availability and uptake in cowpea crop, under different doses of phosphorus. Cowpea crop was grown under ambient (400 µmol mol^?1) and elevated (550 ± 20 µmol mol^?1) CO₂ levels using Free-Air Carbon dioxide Enrichment facility. Elevated CO₂ level increased chlorophyll content in leaves, improved nodulation and nitrogen fixation by the crop. Increase in P dose up to 16 mg kg^?1 soil enhanced nodule development and N₂ fixation under high CO₂ condition. Cyanobacterial inoculation increased nodule weight, leghaemoglobin content in nodules and total nitrogenase activity. Although nitrogen concentration in cowpea seeds decreased in high CO₂ treatment, higher N uptake was recorded. Under elevated CO₂ condition, cyanobacterial inoculation and higher P doses led to enhanced root growth and N₂ fixation and availability of soil nitrogen. The study illustrated the synergistic effect of high CO₂ and cyanobacterial inoculation in enhancing crop growth and availability of soil N, mediated by biological N₂ fixation in cowpea under different levels of P.     

豆科牧草对多花黑麦草化感作用的种间差异

实验室砂培法检测了红三叶、白三叶、杂三叶、黄花草木樨、紫花苜蓿、红豆草和毛苕子等7种豆科牧草茎叶及根的10%水浸提液处理对多花黑麦草种子萌发和幼苗生长的化感作用,结果表明：供试豆科牧草茎叶和根的水浸提液处理对多花黑麦草种子发芽势和幼苗根的生长均有显著（p＜0.05）的化感抑制作用;10%水浸提液处理对多花黑麦草幼叶伸长无显著（p＞0.05）影响,但对幼叶的干物质积累具有抑制作用;豆科牧草对多花黑麦草幼苗生长的化感作用在作用强度和作用机制两方面存在显著的种间差异.     

豆类杂粮作物种子物性参数的试验研究

为了获得豆类杂粮作物相关播种装备的设计依据，选取大豆、绿豆、豌豆、红豆和蚕豆5种典型豆类杂粮作物为研究对象，采用称重法、量筒法、低温烘干法等进行三轴尺寸、千粒重、含水率、密度、休止角、堆积角、摩擦系数、碰撞恢复系数、刚度系数、破碎力、弹性模量和剪切模量等相应物理特性的试验研究。结果表明：所测杂豆种子三轴尺寸的长、宽、高和球度范围分别为4.78～21.11 mm、3.58～15.63 mm、3.61～8.33 mm和0.66～ 0.97；千粒重、含水率和密度范围分别为51.9～1 548.4 g、11.5%～14.4%和1.067～1.323 g·cm^-3；所测杂豆种子休止角和堆积角的范围分别为21.840～35.199°和22.579～33.530°；杂豆种子在PVC板上的静摩擦系数最小，除蚕豆外，其他种子与种子间的静摩擦系数和动摩擦系数均最大。5种杂豆种子中，蚕豆的抗挤压能力最大，绿豆的抗挤压能力最小；豌豆的刚度系数、弹性模量及剪切模量均最大，大豆均最小。杂豆种子物性参数的测量可为杂豆排种器的研发提供理论依据。     

食用豆联合收获减损技术与策略分析

食用豆是我国重要的食用作物，推进其机械化收获提质减损是促进产业发展的重要手段。由于食用豆种类多、地域分布广、种植模式多样，其高效收获装备较为缺乏，是当前生产中迫切需要解决的短板技术问题。结合国内外食用豆产业发展现状、当前联合收获技术研究成果和食用豆机械化收获的特殊性，在对现有联合收获技术的适用性进行分析的基础上，提出适合我国食用豆生产的机械化减损收获技术策略。主要措施包括综合考虑宜机化品种筛选及配套种植农艺、联合收获各环节协同作用和机手收获技能减损。利用以上手段可有效降低收获割前损失、割台损失、脱粒损失和清选损失，同时通过集成应用低损收获割台、高效脱粒清选和物料低损输送技术，可大幅降低食用豆联合收割机作业损失率，减损效果显著