Firstly, I would like to say that it is a great honour to take over the position of Editor-in-chief of Experimental Agriculture, one of the most important journals devoted to publishing original and high quality papers addressing the many facets of agricultural sciences in subtropical and tropical areas. Tradition! I would say that this single word has an enormous meaning for me. I am proud in serving Experimental Agriculture, a journal published by the Cambridge University Press since 1933. Originally titled The Empire Journal of Experimental Agriculture (1933-1964), the publication's mission was ambitious “every new fruit of discovery and invention in the agricultural field”, publishing critical information for improving agricultural systems. So pertinent was the Journal's remit that it was recognised in an article published in Nature in May 27th, 1933. Currently, Experimental Agriculture has an Impact Factor of 1.079 (ISI Thomson Reuters) and stands as a Q1 journal in ‘Agronomy and Crop Science’ (SCImago Journal and Country Rank). In 2015, we received submissions from the five continents, with the majority coming from Asia and Africa. Thank you for considering Experimental Agriculture as a potential journal to publish your paper!

Long-term in situ soil and water conservation experiments are rare in sub-Saharan Africa, particularly in Eastern Africa. A long-term experiment was conducted (2005–2013) on a Vertisol to quantify the impacts of resource-conserving agriculture (RCA) on runoff, soil loss, soil fertility and crop productivity and economic profitability in northern Ethiopia. Two RCA practices were developed from traditional furrow tillage practices: (i) derdero+ (DER+) and terwah+ (TER+). DER+ is a furrow and permanent raised bed planting system, tilled once at planting time by refreshing the furrow and 30% of crop residue is retained. TER+ is ploughed once at planting, furrows are made at 1.5 m intervals and 30% crop residue is retained. The third treatment was a conventional tillage (CT) with a minimum of three tillage operations and complete removal of crop residues. Wheat, teff, barley and grass pea crops were grown in rotation. Runoff, and soil and nutrient loss were measured in plastic sheet-lined collector trenches. Significantly different (P < 0.05) runoff coefficients (%) and soil losses (t ha−1) averaged over 9 yrs were 14 and 3, 22 and 11 and 30 and 17 for DER+, TER+ and CT, respectively. Significant improvements in crop yield and gross margin were observed after a period of three years of cropping This study demonstrated that RCA systems in semi-arid agro-ecosystems constitute a field rainwater conservation and soil fertility improvement strategy that enhances crop productivity and economic profitability. Adoption of RCA systems (DER+ and TER+) in the study area requires further work to improve smallholder farmers’ awareness on benefits, to guarantee high standards during implementation and to design appropriate weed management strategies.

During growth, several cereals store significant amounts of fructo-oligosaccharides (FOS), which have important prebiotic properties. Cereal forage crops are also essential components of many Mediterranean agricultural systems, although little information is available on their dynamics of accumulation and partitioning of dry matter and FOS during growth. Oat (Avena sativa L., cv. ‘Flavia’ and cv. ‘Genziana’), emmer wheat (Triticum dicoccum Schrank, cv. ‘Giovanni Paolo’), barley (Hordeum vulgare L., cv. ‘Diomede’) and triticale (xTriticosecale Wittmack, cv. ‘Rigel’) were investigated for their synthesis of FOS, with a view to development of management approaches for harvesting high-quality forage, and to determine whether these species can be used as natural sources of FOS for commercial use. The study was conducted at Foggia (Italy) and Bella (Potenza, Italy) over two growing seasons (2008–2009; 2009–2010). Dry-matter accumulation and FOS contents were determined for plant fractions from heading to kernel-hard stages. There were large variations across these species for dry-matter partitioning and dry-matter yield (greatest for triticale: 1.24 kg m−2), and for FOS levels of total plants and plant fractions. Emmer wheat and triticale showed greater FOS production (52.0, 41.1 g m−2, respectively). Barley, emmer wheat and triticale showed higher FOS levels in total plants (4.11%, 5.93%, 4.33% dry matter, respectively). Barley, emmer wheat and triticale appear to be the most interesting species for production of forage biomass rich in FOS and as natural FOS sources for industrial use.

When water stress develops post-anthesis, wheat (Triticum aestivum L.) plants have to rely increasingly on remobilization of previously stored assimilates to maintain grain filling. In two-year field trials, we studied more than 20 agronomic and developmental traits in 61 wheat genotypes (27 F4:5 families, 17 parents used for the crosses and 17 standards), comparing plants that were defoliated (DP) by cutting off all leaf blades 10 days after anthesis with intact control plants (CP). Estimated contributions of stem and sheath assimilate reserves to grain weight/spike were from 10–54% and from 24–84% in CP and DP plants, respectively. Stem-related traits were among key traits determining stem reserve contribution (SRC). The most important genetic variables in differentiating genotypes for stress tolerance were biomass/stem, stem reserves mobilization efficiency and grain filling rate (GFR). Balance among traits related to yield maintenance in DP were more important than their high values. In general F4:5 families (FAM), that had been crossed to combine typical breeding traits such as biomass and yield components, showed better tolerance under moderate stress than standards and parents.

Aluminium toxicity is an important abiotic factor limiting the growth and yield of oat plants (Avena sativa L.) and other cultivated species. The objectives of this study were to evaluate the response of oat cultivars at the reproductive stage to aluminium under acid soil conditions and to compare with the responses observed at seedling stage under hydroponic conditions. In the soil, the damage to the above-ground part of the plant was estimated by the morphological response to aluminium, shoot length, shoot dry mass and plant height and, to the below-ground part of the plant as the length of roots and root dry mass. In hydroponics, the primary root regrowth was used to define the level of tolerance. The comparison of the results obtained in acid soil with those obtained in hydroponics demonstrated that both conditions produced essentially the same responses. The use of hydroponic solution can be a valuable tool for phenotyping large populations, especially useful for breeding programmes located in regions were aluminium is not present at toxic levels in the soil.

Gene flow from herbicide-resistant rice (Oryza sativa L.) cultivars can affect the biodiversity of Oryza spp. and can result in the lack of opportunity to control weedy rice through selective herbicides. The aim of the present study was to quantify the outcrossing rate from the herbicide-resistant red rice and rice cultivars carrying three different ALS (acetolactate synthase) alleles using a single plant pollen donor approach. A field experiment was performed using the encircle population combination technique. The main plots comprised the pollen-receptor IRGA 417 cultivar or a susceptible biotype of weedy rice, and the subplots comprised the pollen-donor inbred cultivars IRGA 422 CL and PUITÁ INTA CL, the hybrid SATOR CL or a resistant biotype of weedy rice. Among the pollen-donors, the outcrossing rate for pollen receptor susceptible weedy rice and the IRGA 417 cultivar was 0.0344% and 0.0142%, respectively. Rice cultivars carrying the ALS gene mutations Ala122Thr, Ser653Asn and Gly654Asn showed a similar outcrossing rate of 0.0243%. The outcrossing rate decreased over a distance of up to 3.5 m from the pollen-donor and was not affected by the wind cardinal direction. The risk of gene flow of herbicide resistance from rice to weedy rice should be reduced through the development of new strategies to contain and mitigate gene flow and of the elimination of weedy rice escapees.

A common practice in some South American countries consists in moving around Capsicum chinense cultivars between regions where edaphoclimatic conditions differ notably. The purpose of this research was to compare and relate gas exchange responses with assimilate allocation patterns and flower and fruit production dynamics in a cultivar of C. chinense in three locations with different mean temperatures (19, 24 and 28 °C) along a gradient from 140–1855 m. Leaf gas exchange (leaf conductance, CO2 assimilation and transpiration rates) was measured at 60–70, 110–120 and 140–150 days after transplanting (dat) from seed beds. Dry weight per plant of leaves, stems and roots were determined at 50, 73, 96, 114 and 196 dat. Flowering dynamics and fruit production were followed weekly. A marked reduction (50%) in mean Gs was found at the site with the lowest mean temperature in relation to plants grown at the highest temperature site. Mean daily CO2 assimilation rate was higher for plants in the intermediate site and a reduction of 18 and 42% was found for sites with highest and lowest mean temperature, respectively. We report an adverse effect of low temperatures on growth of C. chinense. Flowering initiation and fruit production was delayed at lower temperatures. An increase in temperature (between 26–30 °C) led to an increase in the number of flowers; below this temperature it remained unchanged. Fruit production is drastically reduced at the lower temperature site due to a large number of aborted flowers and small fruits.

Theaflavins contribute to astringency and brightness while thearubigins contribute to colour and mouth feel of black tea. Green leaf flavan-3-ols influence levels and distribution of theaflavins and thearubigins in black tea and are black tea quality precursor compounds. Caffeine also contributes to tea quality. Although location of production and nitrogenous fertilizer rates influence black tea quality, it is not known if the variations arise from the levels and distribution of the precursor compounds in green leaf or other factors. The variations and distribution of the flavan-3-ols and caffeine in young green leaves of clone TRFK 6/8 due to nitrogen fertiliser rates in seven locations within Eastern Africa were evaluated. Green leaf comprising two leaves and a bud were harvested from each plot, and subjected to HPLC analysis for caffeine, total polyphenol, dihydroxyflavan-3-ols, trihydroxyflavan-3-ols, ratios of trihydroxyflavan-3-ols to dihydroxyflavan-3-ols and total catechins levels. Results were subjected to statistical analysis using split plot design, with locations as main treatments and nitrogen rates as the sub-treatment. Caffeine and flavan-3-ols levels changed (p ≤ 0.05) with location of production, demonstrating that even with use of same cultivar and similar agronomic management quality of tea from one location cannot be replicated in another location. Caffeine levels increased (p ≤ 0.05) with rise in nitrogen fertilizer rate in all locations, but the extent depended on location. Total polyphenols and individual flavan-3-ols showed an inverse quadratic response, except EGCG that linearly decreased (p ≤ 0.05) in some locations, due to increasing rates of nitrogen fertilizer. Similar responses in the black tea quality parameters had been observed in previous studies. The black tea quality results were therefore directly influenced by the green leaf precursor compound patterns. Region specific nitrogenous fertilizer rates need development to ensure high tea quality.

There is continued decline in per capita agricultural productivity in the drier parts of Kenya's central highlands. The declines have been linked to low and declining soil fertility, soil water, high atmospheric heat, prolonged dry-spells and erratic rainfall. Integrated soil fertility management (ISFM) technologies have been developed and tested in the region. Despite their significant impacts, high variability in local soils and climate contributes to large variations and inconsistency in research results among replications. Experimentation is expensive and limited to a few years, sites and scenarios. Crop-growth simulation models suitably complement experimental research, to support decision making regarding soil fertility and water management. This study evaluated the performance of the Agricultural Production Systems Simulator (APSIM) model. APSIM was parameterized and calibrated based on a rain-fed randomized complete block trial (2009–2012) at a research station in Machang’a, Embu County. The study further reported on long-term effects of integrated Nitrogen (N) management from organic residues (goat manure, Lantana camara, Tithonia diversifolia and Mucuna pruriens) and their combination with mineral fertilizers in maize production. The model adequately reproduced the observed trends of maize leaf area index (LAI) and yield response to the test N amendments. Long-term simulations showed that application of 0, 20 and 40 Kg N ha−1 had low inter-seasonal variations (CV = 18–33%) in yields. High yield variability (CV > 56%) was observed in the application of 60 and 80 Kg N ha−1. Application of 40 Kg N ha−1 by combining mineral fertilizer and manure showed 80% chance of harvesting more than 2.5 Mg ha−1 of maize grain yield. Maize stover mulching at 5 and 6 Mg ha−1 with the same N application increased long-term guaranteed grain harvests to 3.5 Mg ha−1. This is when complemented with 90 Kg P ha−1. This integrated N and soil water management is thus recommended. For subsistence farming, low-cost recommendations are geared towards some ‘guaranteed’ yield stability each cropping season. This recommendation underpins low-cost technologies that reduce production risks among small-holder farmers who faced with intermittent financial problems, to improve food security. However, there is need to evaluate and verify that there is a positive balance of primary nutrients such as N, P and K in such a fertility and water management option. Its effects on C:N levels ought to be evaluated as well.

Recent years have seen increasing political interest and growing public health awareness and advocacy for diversifying diets into highly nutritious traditional vegetables, fruits and other nutrition-sensitive crops as a more viable approach to mitigate the growing scourge of malnutrition due to unhealthy and imbalanced diets. These foods contribute essential micronutrients, vitamins, antioxidants, and other health-related phytochemicals to staple-based diets and their consumption is crucial for the attainment of several Millennium Development Goals. Despite their nutritional benefits and the high farm gate values per unit of land, the production and marketing of traditional vegetables from Tanzania and other countries in sub-Saharan Africa are constrained by factors such as poor quality seeds, lack of appropriate market information and support systems, and lack of consumer awareness of their nutritional importance. This paper investigates the determinants and pathways for smallholder participation in traditional African vegetable production and identifies entry points for farmers to increase traditional vegetable production by linking nutritional awareness and promotion with potential high value markets. A primary survey of 181 traditional vegetable growers from five regions of Tanzania indicates that perceptions about the nutritional value of traditional African vegetables are a main driver of household production decisions in the sector. The results of this study provide evidence that farmers tend to grow more African traditional vegetables as compared to other crops based on their increased level of perception towards nutritional value of traditional vegetables along with other factors such as their market value, timely availability of quality certified seeds, willingness to invest in labour, required training for women and better access to credits. Farm size negatively affects growing traditional vegetables, implying that on a comparative basis, smallholders tend to grow more traditional vegetables than larger-farm operators. Thus, more attention should be given to reducing production and its associated transaction costs by ensuring timely access to quality certified seeds, ensuring optimal use of inputs and increasing labour productivity, particularly for smallholders.

Limited information is available concerning the influence of nitrogen fertilization jointly on yield response, nitrogen use efficiency (NUE) and grain quality of durum wheat under semi-arid Mediterranean conditions. The study focused on evaluating, through a systematic study, over three seasons in southern Italy the effects of three nitrogen fertilization rates (0, 80 and 160 kg N ha−1 – N0, N80 and N160), on grain yield, yield components, nitrogen efficiency indices and grain quality characteristics of three durum wheat genotypes (‘Creso’, ‘Trinakria’ and ‘Line 25’) from different breeding eras to achieve a more sustainable fertilization management of the durum wheat crop. We found that nitrogen fertilization at 80 kg N ha−1 was able to maximize the yield performances (2.1 t ha−1 year–1) of the crop and keep NUE index at an acceptable level (16.3 kg kg−1). On the other hand, nitrogen fertilization at 160 kg N ha−1 improved grain quality measured through protein (up to 14.3%) and dry gluten concentration (up to 12.8%), but had a detrimental effect on grain yield and nitrogen efficiency. Among the genotypes studied, ‘Trinakria’ showed the greatest potential to utilize nitrogen fertilization to improve grain yield and NUE (at N80) and quality (at N160), ‘Line 25’ made good use of N80 both for yield and quality, whereas ‘Creso’ proved wholly unresponsive to nitrogen. The effect of N fertilization on grain yield and N use efficiency depends on rainfall distribution, giving the best results when about 80% of total rainfall occurred from sowing to heading. Overall, our data show that in seasons with regular rainfall in quantity and distribution, combining no more than 80 kg ha−1 of nitrogen fertilization with genotypes characterized by a more efficient response to nitrogen, is a useful tool to improve the agronomic and quality performance of the crop, ensuring, at the same time, a more environment-friendly nitrogen fertilization.