A pot experiment was carried out to study various aspects of growing peanuts in highly calcareous soil, with special reference to iron chlorosis. There was good agreement among the criteria used to evaluate the need for iron and the effectiveness of different chelates or methods of application (i.e. visual symptoms, chemical diagnosis and yield response). Of the iron chelates tested, Sequestrene 138 proved the most effective. Promising results were also obtained by coating seeds with chelate as an iron starter, followed by an additional top dressing. The results indicate the possibility of growing peanut economically in the highly calcareous soil tested using iron chelate —Fe EDDHA (Sequestrene 138).

The response to sulphur (S) and irrigation of mustard although site-specific, is less studied across sites. Economics and greenhouse gases (GHGs) emissions are other important considerations for developing resource-efficient technologies, but hardly studied in mustard. The objectives of this study were to appraise productivity, economics and GHGs emissions under three irrigation regimes combined with four levels of S, laid out in a split plot design with three replications. Results showed that two irrigations at 30 and 60 DAS combined with 60 kg S ha−1 resulted in highest gross and net returns, which were 30.9 and 37.2% higher than that in single irrigation at 30 DAS, and 47.2 and 68.0% higher than that in single irrigation at 60 DAS without S application, respectively. Estimated GHGs emissions from common inputs (machinery, diesel, fertilizer and insecticides) of mustard were 1486.2 kg CO2 eq ha−1 with greater share (95%) of fertilizer. Econometric analysis predicts that 1% increase in irrigation and S use will lead to 10.29 and 9.98% increase in mustard yield, respectively.

The aim of this work was to determine the importance of the genotype-by-environment interaction in true potato seed breeding. In order to establish the importance of this type of interaction, experiments were sited across three Peruvian locations, San Ramon (warm mid-altitude slopes), Huancayo (cool Andean highlands), and La Molina (coastal desert). The genotype by environment interaction significantly affected tuber yield in all breeding materials (4x-4x from random or selected parents, and 4x-2x crosses). For example, the 10 most outstanding 4x-2x crosses for tuber yield were different when tested in warm and cool locations. Similarly, two clones derived from 4x-4x crosses were among the best 15 hybrids assessed in the two lower altitude locations. These two offspring provide examples of crossover genotype-by-environment interaction for tuber set, non-cross order genotype-by-environment interaction for tuber yield and lack of genotype-by-environment interaction for days to flowering. Because top yielding true potato seed offspring for each location were locally adapted, cultivars or advanced selections from the target area should be the parental sources of true potato seed offspring.

Nutrient deficiency is a major constraint in tef (Eragrostis tef (Zucc.) Trotter) production in Ethiopia. In the past, a blanket recommendation of nitrogen (N) and phosphorus (P) fertilizers has been applied regardless of the diversity of agroecological zones and soil types. As crop responses declined with widespread deficiencies of nutrients, farmers have lost interest in applying the recommended fertilizer rates. The present study was conducted with the objective of quantifying the response of tef to different rates of N, P, potassium (K) and sulphur (S) fertilizers under balanced application of the nutrients other than the one under investigation. In each region, the same set of trials was implemented on farmers’ fields for three years. All trials were implemented on Vertisols across four agroecological zones (AEZs). The treatments were seven rates of N, six rates each of P and S and eight rates of K with a basal application of zinc (Zn) and boron (B). The results showed that the most limiting nutrient is N followed by P in each agroecological zone on the Vertisols. There was clear evidence of increases in grain yield with increasing rates of N and P, but the responses to K and S rates did not follow clear trends across AEZs. With balanced application of the other nutrients, 23–92 kg N ha−1 increased grain yield by 11–92%, while 10–40 kg P ha−1 increased yields by 12–33% over the control in the different AEZs. Based on results from dose–response models, it is concluded that the agronomic optimum rates for tef production are 69 kg N, 20 kg P, 30 kg K and 10 kg S ha−1 in the cool sub-moist mid-highlands and the tepid sub-humid mid highlands; 92 kg N, 30 kg P, 15 kg K and 10 kg S ha−1 in tepid moist mid highlands but 69 kg N, 10 kg P, 15 kg K and 10 kg S ha−1 in the tepid sub-moist mid highlands. On Vertisols not covered by this study, these recommendations should be subject to appropriate soil and plant analysis. We also recommend further studies on the nutrient requirement of tef on other soil types and AEZs.

In Indonesia, management practices that reduce soil fertility could be limiting cocoa (Theobroma cacao L.) production. To address this, we investigated the effects of fertilizers and organic amendments comprising different combinations of NPK + urea, dolomite, and manure-based compost on soil properties and cocoa productivity. We extended an existing field experiment in South Sulawesi, Indonesia, to assess these treatments’ effects on cocoa trees from the age of 2.9 years to 7.4 years. The treatments were first applied 5 months after planting and subsequently twice a year. Soil analyses were performed before planting, after 3 years, and finally after 7 years. Productivity was assessed yearly between the age of 3.5 and 7.4 years. The highest yields were obtained from the plots receiving compost, although the yield benefits diminished over time. Inorganic fertilizer alone doubled the yield compared to the control, while the yields with compost and compost + fertilizer were three times that of the control. With dolomite alone, the yield cumulated over 4 years was 41% higher than the control. The positive effect of compost on cocoa yields can potentially be attributed to (1) physical changes increasing soil water availability, (2) the chemical improvement of nutrient availability, and (3) biologically, by promoting the activity of beneficial organisms. The application of dolomite increased soil pH, Ca, and Mg contents. Soil organic carbon greatly declined in the composted treatments, even though 10 kg of compost was applied per tree per year, probably because of the low C:N ratio of the compost. Future studies should assess different fertilizer formulations and combinations with organic inputs and explore the mechanisms by which compost promotes cocoa productivity.

Experiments in bulbil nurseries and field sisal were carried out in N.E. Tanganyika, 5°S, 39°E, 200 m. above sea level, at a mean annual rainfall of 1160 mm., on deep red loam. The discussion covers the establishment of sisal through a polythene mulch, the control of weed growth, the persistence of polythene of different thicknesses and from different sources, and some effects on growth of the sisal and on soil properties. A mulch of black polythene improved the growth of bulbil nurseries by 30 per cent or more, due to conservation of soil moisture and elimination of weed competition and disturbance associated with the removal of weeds by hoeing. For nurseries 150-gauge material was preferred, but there were important differences in the persistence of material purchased from two sources. Where black polythene is used in a nursery the density can be increased from 80,000 to 110,000 plants per hectare, to help offset the high cost of the material. A mulch of 250-g. black polythene controlled weeds in field sisal but did not improve growth.

The results of field experiments conducted in the spring seasons (February/March to June) of 1980 and 1981 indicate that grain yields of sorghum increased with increase in frequency of irrigation. Crops sprayed with atrazine or CCC yielded more than the unsprayed control; maximum yields were obtained by the application of atrazine at 200 g ha−1. Water use efficiency decreased with increase in irrigation but increased as a result of spraying crops with either chemical. Irrigation water can be saved by the spraying of atrazine or CCC onto spring-sown sorghum.

Weekly measurements in a maize silage crop grown at three populations, each at three levels of nitrogen, showed that leaf area index, crop growth rate and total whole plant yield were greatest at the highest plant population (430,000/ha.) and lowest at the low population (47,000/ha.). At the former maximum yields of dry matter and crude protein occurred approximately seventy-five days from sowing, when the cob contribution was small. With wider spacing maximum yields occurred later. At the intermediate population (107,000/ha.), and with adequate nitrogen, sowing on the square was superior to sowing in wide rows. Nitrogen did not preferentially affect the relative dry matter yield of any growth component; plant population had a greater influence on total whole plant yield than nitrogen.

Four tomato varieties (Harvester, Pusa Early Dwarf, Ife No. 1 and Ibadan Local) were grown in three ecological zones of Western Nigeria, at a range of densities from 10,000 to 40,000 plants/ha. The highest yield of fruits was obtained at a plant population of 30,000 plants/ha. Pusa out-yielded the three other varieties. Fruit number per plant declined as plant density increased.

The effects of iron pyrites, organic materials and micronutrients on the yield of rice and wheat and on the amelioration of saline sodic soil were studied at Kanpur. The grain yield of the first crop of rice increased from 1.37 to 2.97 t ha−1 following application of pyrites at 50% of the estimated gypsum requirement. The grain yield of succeeding wheat and rice crops also increased significantly with pyrites treatment. These increases were associated with marked decreases in pH, electrical conductivity, exchangeable and soluble sodium content and bulk density of the soil and with an increase in its hydraulic conductivity. The beneficial effect of pyrites was increased with the application of rice straw, Sesbania as green manure and micronutrients, the pyrites plus Sesbania green manure treatment being the most effective.

The relation between some growth parameters in polybag oil palm nursery seedlings were assessed. ‘Non-destructive’ parameters such as leaf number, seedling height and girth were highly and positively correlated with one another and with the dry weight of seedlings. Amongst the ‘destructive’ parameters only leaf area, height/weight ratio and fresh weight were positively correlated with dry weight. The Leaf Area Index was poorly correlated with other parameters examined. The relevance of these findings to the selection of oil palm seedlings for transplanting into the field is discussed.

A two-year study was undertaken in a tropical dryland agro-ecosystem to evaluate the effect of the application of soil amendments with contrasting chemical natures on crop productivity, grain yield, N-uptake and N-use efficiencies. The treatments involved the addition of equivalent amounts of N (80 kg N ha−1) through chemical fertilizer and three organic inputs at the beginning of the annual cycle: Sesbania aculeata shoots (high quality, C/N 16), wheat straw (low quality, C/N 82) and Sesbania+wheat straw (high and low quality combined, C/N 47), together with a control treatment. Test crops consisted of an annual sequence of rice and barley, sown in the rainy and winter seasons, respectively. Fertilizer and Sesbania inputs resulted in higher total net productivity (TNP) for the rice crop (47 % and 32 % increases over the control, respectively) than the combined (+28 %) and wheat straw treatments (+10 %). During the succeeding barley crop, maximum TNP was recorded in the Sesbania+wheat straw treatment (+52 %), followed by wheat straw (+43 %), fertilizer (+19 %) and Sesbania (+17 %). The TNP and grain yields of both crops added together were higher in Sesbania+wheat straw and fertilizer treatments compared to a single applications of either Sesbania or wheat straw. The Sesbania+wheat straw and fertilizer treatments resulted in more efficient utilization of N compared to the other treatments. Crop roots played a pivotal role in N-recovery from the soil and their N concentrations differed significantly (p < 0.05) due to the application of soil amendments. Across different treatments, crop root biomass was strongly correlated with crop N-uptake (r = 0.81, n = 10, p < 0.05), recovery efficiency (r = 0.81, n = 8, p < 0.05) and agronomic efficiency (r = 0.81, n = 8, p < 0.05). It is suggested that the combined application of high and low quality resources modulated N release, resulting in relatively higher productivity through the annual cropping cycle. Such combined inputs may prove useful in developing low input, environment friendly soil management practices in tropical dryland agro-ecosystems.

The response of groundnut plants to CCC was investigated by applying concentrations of 0, 500, 1000 and 1500 ppm three times as a foliar spray. CCC at 500 ppm gave more kernels, and heavier yields of pods, kernels and oil, than 1000 or 1500 ppm or the control treatment. Application of CCC resulted in a greater percentage of shell and of moisture in the whole pod than in the control.

Good data handling is a prerequisite for good statistical analysis and interpretation. This paper begins by distinguishing types of numerical data. Care for original data and the risks involved in any process of copying data are emphasized. After discussion of the entry of data into a computer file, problems of scrutiny and checking are discussed at length. An attempt is made to suggest what action should follow when such scrutiny discloses anomalies in some values; if explanations can be found, or if clear evidence indicates corrections that are needed, no problem arises, but otherwise various subjective responses need consideration. Advice is offered on the numbers of digits to be retained in computations and reports. A final section presents ideas on the filing of data and analyses from an experiment.

The effects of radiation conditions and nitrogen (N) availability on triticale were investigated. The relationship between shading (S) and N supply and their effect on the industrial use of triticale flour were studied. Incident radiation/shade conditions affected all the parameters measured. Nitrogen supply influenced yield, protein content, sodium dodecyl sulphate-sedimentation index (SDS-SI), alkaline water retention capacity (AWRC), cookie factor and diameter of four cookies (D4C). The proportion of proteins of high molecular weight was increased with nitrogen supply and pre-anthesis shade, while post-anthesis shade increased proteins of lower molecular weight. The interaction between variety and N supply was significant for yield, SDS-SI and AWRC. Only yield and specific weight were affected by N × S interaction. Significant effects of the interaction of variety, N supply and shade conditions were observed for specific weight.

Water stress is arguably the most limiting factor affecting cereal productivity in the world and its effects are likely to increase due to climate change. It is therefore imperative to have a wide-ranging understanding of water stress effects on crop physiological processes so as to better manage, improve and adapt crops to future climates. A field study was carried out to investigate the influence of four moisture levels on the following: (1) flag leaf CO2 assimilation and flag leaf carbon content; (2) the utility of flag leaf spectral reflectance to monitor leaf water status and as an indicator of biomass and grain yield; and (3) biomass and grain yield performance of four spring triticale genotypes in a dry winter environment (steppe, arid climate). The experiment was carried out in a factorial arrangement of four moisture levels and four spring type triticale genotypes). Soil moisture level significantly influenced biomass accumulation, grain yield, CO2 assimilation, flag leaf carbon content and spectral reflectance. Grain yield levels ranged from 0.8 to 3.5 t ha−1 in 2013 and 1.8 to 4.9 t ha−1 in 2014. CO2 assimilation was significantly higher under well-watered (WW) conditions (9.92 µmol m−2 s−1 in 2013; 11.64 µmol m−2 s−1 in 2014) and decreased gradually with moisture level to 1.82 and 4.74 µmol m−2 s−1 under severe stress (SS) in 2013 and 2014, respectively. Flag leaf carbon content was significantly higher under water limited conditions compared to WW. Normalised Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI) and Water Index (WI) were significant and positively correlated to biomass and grain yield. WI was particularly strongly correlated to biomass (0.72***) and grain yield (0.55***). However, no clear varietal effects were detected. This study revealed that carbon tends to accumulate in flag leaves under water stress and that flag leaf carbon content is influenced more by the export capacity of the flag leaves than on CO2 assimilation rate. WI was found to be superior index in monitoring water stress in triticale compared to NDVI and NDWI. Above all, spring triticale proved to be adaptable to steppe (dry) climate of Limpopo and that livestock farmers in the province can successfully grow triticale for silage under MS conditions.

Factorial experiments are described and the importance of interactions emphasized with suggestions about how they should be interpreted. A distinction is made between factors introduced only to see if they will provoke an interaction and those actually under study. Split-plot designs receive special attention. Factorial experiments often involve a large number of treatments and ordinary block designs may be ineffective in controlling environmental variation. If factors have few levels, as in exploratory experiments, the usual device for reducing block size is confounding, which is explained along with single-replicate experiments, partial replication and hidden replication. Alternatively, non-orthogonal designs and analysis of data by nearest-neighbour and spatial methods might prove useful. The need for randomization and the role of significance are discussed. It is pointed out that interactions can sometimes be avoided by transformation of the variate.

Mature lucerne on shallow granite sand was irrigated at different intervals, determined by four factors, 0·4, 0·6, 0·8 and 1·0, applied to daily evaporation (E0) as measured by a USWB Class A pan. Moisture balances were calculated for each treatment, and when the accumulated sum of daily evaporation, multiplied by the appropriate factor, reached 1·2 inches, which was about 50 per cent of the available moisture in the top 2 feet of soil, this amount of water was applied to the plots of the treatment concerned. Irrigation on the basis of 0·8 E0 gave the but overall results, although the highest yield from a single cut was obtained with the irrigation frequency defined by 1·0 E0. During the rainy season yields from all treatments declined markedly, those from the most frequently irrigated treatment showing the greatest drop. The lucerne under the irrigation regimes defined by 0·4 and 0·6 E0, although subjected to considerable moisture stress in the dry weather, suffered no lasting ill effects and yielded well during the rains. The experimental area was almost certainly subject to advective energy but the results are considered valid for local conditions.

Data from 110 on-farm vegetable trials conducted in Jamaica were examined to seek guidelines as to how on-farm trials should be executed in order to obtain quality data. The results show that while one-way blocking is useful in designing experiments it may sometimes be inefficient and that two-way blocking is generally preferable. If only a small number of trials can be conducted then it is important that up to four or five replications of each treatment are used at each site. Plot sizes should be larger than those used for on-station trials. Due to low correlations between results from different sites, experiments should be conducted at many sites. Thus a large number of trials should be planned to allow for treatment–environment interactions and trial failures.