A randomized complete block design experiment with six aluminium (Al) concentrations was carried out to evaluate the effect of Al on nutrient content, plant growth, dry matter production and Al-induced organic acid exudation in rambutan (Nephelium lappaceum). One rambutan cultivar was grown in nutrient solution at pH 4.0 with (1.0, 2.3, 4.1, 6.7 and 10.2 mM Al) and without Al. The results of this study confirms that this crop is highly tolerant to Al in the rhizosphere as evidenced by: (1) a root tolerance index (RTI) of 0.85 when plant roots are exposed to Al concentrations as high as 3.5 mM; (2) root tissue Al concentrations as high as 6800 mg g−1 and the plants survived; (3) number of leaves, plant height and stem diameter being little affected when plants were grown at an Al concentration in the soil solution as high as 3.5 mM; (4) although plants exhibited leaf abscission, they were able to tolerate Al concentrations in the nutrient solution as high as 10.2 mM during the experimental period. No evidence of organic acid exudation was found in this study. Accumulation of Al in leaves, stems and roots suggests the existence of an Al-sequestration mechanism in rambutan which may involve an Al-ligand complex which translocates from roots to shoots, where it may accumulate in leaf vacuoles.

Predicting in-season crop yield is a unique tool for drawing important crop management decisions for precision farming. Field experiments were conducted at two locations in northwestern India under different agro-climatic zones to predict and validate spring maize yield using various in-season spectral indices. The spectral properties measured with leaf color chart (LCC), chlorophyll meter (SPAD meter), and GreenSeeker optical sensor were used to predict grain yield. A power function based on the Normalized Difference Vegetative Index (NDVI) measured with GreenSeeker optical sensor at V9 growth stage (9th leaf with fully exposed collar) presented higher values of coefficient of determination and explained 61% of the variability in spring maize grain yield, whereas NDVI measured at early and late growth stages were not reliable for the purpose. The spectral properties recorded with the SPAD meter and LCC rendered better grain yield estimates at VT growth stage (tasseling) and were respectively able to explain 75 and 76% variability in grain yield. The developed models were validated on an independent data set from another field experiment on spring maize. The normalized root mean square error (NRMSE) was <10% for LCC and SPAD at all the growth stages and at V9 growth stage for NDVI. The LCC, SPAD, and NDVI values adjusted with cumulative growing degree day were not helpful to improve NRMSE.

The study at hand measures the value of improving data governance and access in the Supporting Soil Health Interventions (SSHI) project in Ethiopia. We applied two separate but interlinked models, one qualitative and one quantitative, to create a new framework enhancing the traditional cost–benefit analysis. The qualitative analysis provided novel insights into the specific types of value and the mechanisms through which they are generated. These results underpinned the development of an innovative framework to measure this perceived value quantitatively. By combining the quantitative and qualitative framework, the study demonstrated that it is possible to generate plausible and credible quantitative estimates of both costs and benefits of data governance and access. While acknowledging that the estimates are only illustrative, the case study results suggested on a direct cost measure, at a particular point in time, the SSHI data governance activities yielded a negative return. However, indirect social and public benefits are rarely quantified, but this paper shows that relatively few “indirect” benefits (current but unmeasured, or measurable but in the future) are necessary to reverse that view, at least from the point of the economy more generally.

In the past two decades, a growing body of work on research stations and farmers' fields in Southern Africa has provided evidence that fertilizer trees can improve the productivity of land, increase crop yields and contribute towards climate change mitigation and adaptation. In a recent issue of Experimental Agriculture, Coe et al. (2019) published analysis of risks associated with adopting agroforestry in Malawi. The article contains several factual inaccuracies about agroforestry and misinterpretations of earlier work. Our aim in this correspondence is, therefore, to point out the key problems, seek clarification from Coe and co-workers, and stimulate wider scientific debate on the perceived risks of adopting agroforestry.

The potential was demonstrated of using sodium chloride and sodium metabisulphite as chemical preservatives during pre-drying storage of wet cassava chips, and during slow sun-drying under adverse weather conditions. Both chemicals permitted chips to maintain a good colour and texture and prevented gross microbial deterioration.

In upland rice, seed soaked in CCC for 24 hours before sowing or sprayed with CCC 10, 21, 42 and 63 days after sowing, showed severe lodging. Effects of CCC on the number of paniclebearing tillers, number of good grains in 1000 grains, weight of 100 good grains and grain yield were not significant. On the other hand CCC prevented lodging in swamp rice, with the lowest percentage when foliar spray was given 21 days after transplanting. CCC failed to increase the number of panicle-bearing tillers and grain yield in swamp rice.

Rapid initiation and growth of nodal roots (NR) are critical for the establishment of post-rainy season (rabi) sorghums grown in drying soil. The growth of NR was studied in sorghum in the field when sown at different depths in order to vary the crown depth, when different levels of irrigation water were applied to create different moisture contents in the topsoil, and in a number of cultivars to assess genotypic variability. Variation in sowing depth did not result in differences in NR growth, partly because of the capacity of sorghum to vary the mesocotyl length, which brought the crown to approximately the same depth. Different soil moisture levels in the field affected the elongation rate of NR, but not their initiation. Genotypic variation existed in the thermal time required for NR initiation and rate of elongation. The variation in NR growth was independent of the variation in shoot growth. The genotypic variability in NR growth offers an opportunity for combining root-related traits with useful agronomic characters.

Ammonium has been reported as a ‘preferred’ nitrogen (N) source for sugarcane (Saccharum spp.), which can improve N use efficiency (NUE) in this crop. We aimed to evaluate the preferential uptake of ammonium and nitrate in sugarcane genotypes contrasting with NUE under controlled conditions. Four sugarcane genotypes previously selected by another experiment (ER: efficient and responsive; ENR: efficient and nonresponsive; IR: inefficient and responsive; INR: inefficient and nonresponsive) were grown in a growth chamber and fertilized with two 15N-labeled forms [(NH4)2SO4 (15N-NH4+) or KNO3 (15N-NO3−)]; soil was used as substrate. Plants were evaluated at three time points: 0, 24, and 72 h after 15N-fertilization. For the efficient genotypes (ER and ENR), the soil NH4+ levels were about 20% lower than those found for the inefficient genotypes (IR and INR) indicating greater N extraction by the plant. Nitrogen derived from fertilizer (NDFF) and 15N recovery from fertilizer (15N RFF) in roots were influenced by the genotypes, in which responsive genotypes (ER and IR) presented a mean value 40% higher than the genotype INR, showing that greater absorption is more related to response than efficiency. Three days after N application, NDFF and 15N RFF from 15N-NH4+ were greater than 15N-NO3− in 40% and 65% for the roots and aerial part, respectively. The results of this study confirmed that sugarcane presents preferential uptake of NH4+ N form 3 days after fertilization. The use of nitrification inhibitors can be considered for providing a longer NH4+ residence time in the soil, also contributing to augmenting the NUE in sugarcane.

One of the major research activities of the Mauritius Sugar Industry Research Institute (MSIRI) is the breeding and selection of sugarcane varieties adapted to the different agro-climatic environments. Most of the on-farm experimentation is carried out in the fields of miller-planters (planters who own the sugar mills), where resources in terms of land, labour and other inputs are usually easily available. The non-miller-planters are operating in environments which are not always similar to those of the miller-planters. There is a need for on-farm experimentation under these conditions in order to improve productivity. Variety trials, observation plots and industrial trials to compare commercial varieties with promising and newly released ones have been established on-farm in order to improve the adoption rate of new varieties. The paper elaborates on the objectives of this major extension activity during the last decade. A major inference is that the planters obtain first-hand information on promising varieties prior to their release for commercial plantation, hence influencing their decision for adoption or rejection. Moreover, additional information on the performance and behaviour of these promising varieties is made available to research staff.

The yields of extractable protein, and its rates of production, were measured with seven crops given large dressings of nitrogen, which produced lush plants with small fibre to juice ratios, increased the nitrogen content (as percentage of dry matter) in five species, improved the extractability of protein N in three, and gave significant increases in both dry matter and protein yields of non-legumes. However, yields were affected more by climate than by the N fertilizer. It is felt that non-legumes given large dressings of fertilizer N, as well as leguminous fodders, could be used efficiently if their excess protein was extracted and used for human consumption.

An extended assumption in maize breeding is that potential yield (Ymax) predicts yield (Y) under stress conditions (here, Ymin), justifying genotypic selection under moderately high-yielding environments. Moreover, it has been postulated that Y tolerance to stress is relatively independent on the main stress factor involved in Y reduction (cross-tolerance). We carried out an analysis of four datasets from Argentine Federated Farmers network (2010/11, 2011/12 and 2012/13, 11 locations and >20 hybrids) and the National Institute of Agricultural Technology (INTA) (12 locations, 13 hybrids). No consistent relation was detected between Ymax and Ymin (r2 < 0.14) in each dataset. Y stability assessed by the coefficient of variation positively related to Ymin (r2 > 0.68 across datasets) but not to Ymax. Depending on the dataset, 40–70% of the hybrids had a varying Y performance (from worse to better) compared with the average of all hybrids, with no consistent advantage of hybrids with high Ymax within the environmental range explored in the dataset. In order to assess the existence of cross-tolerance, INTA environments were divided into two groups: water-limited environments and environments exposed to other(s) type(s) of stress. While a relation was found between average yields (r2 = 0.64) of each hybrid in both environments, there was no relation for Y stability (r2 = 0.07). Taken together, our results suggest that: (i) a high Ymax is not a good indicator of high Y tolerance under stressful conditions; (ii) Y tolerance is related to high Y stability, which may or may not involve a Y penalty under high-yielding environments; (iii) around 50% of the genotypes have Y performance that is not consistently worse or better than the average throughout the range of environments explored and (iv) cross-tolerance to stress is a peculiar trait of some hybrids, but most of the hybrids analysed here do not show cross-tolerance.

At Ukiriguru, in Western Tanzania, three levels of sulphate of ammonia were compared on natural pastures on hardpan soils. Yields of dry matter were substantially increased by nitrogen fertilizer and at high stocking rates the growth of cattle on different treatments followed fairly closely the amounts of dry matter available.

A simple method of studying the reaction of detached cacao pods to Phytophthora palmivora is described. The results, which bear a close relation to field observations, are discussed in this context.

Soil analysis on samples taken from apple orchards in Khorasan and quince orchards in Esfahan, suggested that at a sampling depth of 20–45 cm., the critical soil concentration of calcium carbonate at which chlorosis might appear seems to be 14–15 per cent for apple and 39–40 per cent for quince. The incidence of lime-induced chlorosis was accompanied by lowered leaf Ca/K ratios. The application of various iron chelates to chlorotic trees not only benefited yield of apples but also exercised a residual effect in succeeding seasons.

Two different collections of local sorghum strains, grown in 1975/76 and 1976/77, showed considerable and useful variation in plant height at maturity, head type and exsertion, grain colour, and days to flowering and maturity. A close and positive correlation was found between days to flowering and to maturity, and x2 tests also showed close associations among other characters. Implications of these variabilities for sorghum improvement are briefly discussed.

Ten tomato varieties, tested at three locations for 3 years in Western Nigeria, gave variety × environment interactions, indicating that some were only suitable for specific areas and none possessed wide adaptation. It is suggested that Western Nigeria could usefully be divided into sub-zones in which specific varieties could be developed.

Greater yam (Dioscorea alata), a popular crop in India, is cultivated widely in Orissa state, India. In spite of the availability of several improved varieties, farmers preferred the local landraces. An investigation was carried out to identify whether the varietal preferences of yam farmers in two production systems, subsistence and commercial, were different. While the subsistence farmers demanded the yam varieties adaptable to a wide range of soils, the commercial farmers preferred the anthracnose-resistant cultivars. This study demonstrated that the farmers' varietal preferences were highly influenced by the production systems. Identifying the convergence/divergence of varietal preferences across production systems can help breeders to develop the high impact varieties.

The effects of day length extension and night interruption on flowering responses of St John's Wort (Hypericum perforatum) plants were investigated. Field-grown plants were subjected to five different day lengths (11, 13, 15, 17 and 19 h d−1) or night interruption for 70 days. The results indicated that St John's Wort is a long-day plant requiring a critical day length of 15 hd−1 for flowering induction. Both day length extension (duration longer than 15 h) and night interruption, with artificial light (fluorescent lamps that delivered 30 μmol m−2 s−1 photosynthetic photon flux density at plant height) were effective for flowering induction and seed setting. Day length extension or night interruption experienced by the maternal plant also affected the germination responses of the seeds produced. Plants that had received 19 h of day length treatment produced seeds with better germination responses. Night interruption with daylight type fluorescent lamps was also effective for producing relatively high quality seeds, although these seeds had slightly lower germination rates and longer mean germination time than seeds produced under 19 h of day length. Such a night interruption system could be considered for seed production of St John's Wort on a commercial scale.