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.

Experiments were conducted during the winter seasons of 1992–93 and 1993–94 at the Lumle Agricultural Research Centre and its off-station research site at Lopre in Nepal to study the agronomic performance and profitability of barley (Hordeum vulgare) and peas (Pisum sativum) mixed intercropping (that is, without any row arrangement) in the subsistence farming systems of the Nepalese hills. Sole crops of barley (cv. Bonus and Local) at 100kg seed ha−1 were compared with a pure stand of peas (cv. Tikot Local) sown at 60kg seed ha−1 and with peas intercropped with both varieties of barley at 100:40 or 100:20 kg seed ha−1. Results across two locations for two seasons showed that the barley+peas intercropping was advantageous in terms of overall grain yield, land equivalent ratio (LER), monetary advantage, economic return and dietary provision in the subsistence farming system. It also provided yield stability under adverse climatic conditions. Barley genotypes differed in their suitability for intercropping with peas. The yield of Local barley was reduced when peas were intercropped with it at both seed rates but this was not so with Bonus. The most appropriate combinations to realize the maximum advantage from intercropping were Bonus barley+peas at 100:20 kg seed ha−1 and Local barley+peas at 100:40 kg seeds ha−1. A combination of Bonus barley and peas at 100:20 kg seed ha−1 enabled farmers to harvest an additional 400 kg grains ha−1 from peas without significantly reducing the grain yield of barley. The study also verified through formal experimentation that the traditional practice of mixing barley and peas is advantageous.

Field studies designed to investigate the effects of sett size and spacing on tuber yield of white Guinea yam were conducted in three locations over a two year period in the rainforest and savanna zones of Nigeria. Sett weights larger than 400 g could be used for maximum tuber yields in both forest and savanna zones. Spacing had no significant effects on tuber yield in the savanna zone, but optimum spacing has yet to be identified in the forest zone.

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.

A three-year experiment examined the possibility of increasing the cropping intensity of a medium-deep Alfisol (red soil) by using sequential, relay, ratoon or intercropping systems. It was found that a short-season mungbean (Vigna radiata) crop could be taken before the commonly-grown castor crop but that castor yields were reduced by the delayed sowing. If the castor was sown after the harvest of mungbean in a sequential system the profits were less than from a sole castor system. Relay-sowing the castor 20 days before the harvest of mungbean gave 9 $US ha−1 greater profit than sole castor, but this is probably not enough to justify the more intensive double crop system. On the other hand a reasonable yield of horsegram (Macrotyloma uniflorum) could be produced after an early pearl millet crop, giving a worthwhile extra profit of 21 $US ha−1 compared with sole pearl millet. Ratooning the sorghum gave ratoon yields that averaged only 14% of the first crop, so this system was not considered suitable for these lighter Alfisols.

Intercropping systems of pearl millet/groundnut, sorghum/pigeonpea and groundnut/pigeonpea gave average yield increases of 24, 47 and 46%, respectively, compared with both component crops grown separately. Compared with growing only the higher value sole crop, increases in profits were 16, 82 and 120 $US ha−1 for the same three systems, respectively. It is concluded that intercropping systems provide the best opportunity for increasing cropping intensity on medium-deep Alfisols.

Analysis of a 4-parent diallel cross showed marked heterosis for yield and its components in two crosses (Mexipak × Dirk and C273 × AU49) under irrigation, while little or negative heterosis occurred under moisture stress. A large part of the genetic variation among crosses for yield, and most components of yield, was attributed to the general combining ability, indicating that the additive effects were important. Reciprocal effects and various interactions were insignificant except for kernel weight, which suggests that effective selection could be made under irrigation of genotypes adaptable to moisture stress.

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.

Three cultivars of Stylosanthes guyanensis, under two management regimes, were assessed for yield, quality, palatability and persistence under grazing. During the dry season progressive leaf abscission resulted in unpalatable bare stem, but both leafy stem and fallen leaf remained palatable. Between May and September there was a decline in crude protein (from 16 to 11%), phosphorus (0.22 to 0.18%) and potassium (2.3 to 1.7%), but not in digestibility (average 53%). Partial rather than total accumulation of wet season growth ensured less trampling damage, hence better persistence. Cultivar ranking for persistence and leaf yield was Schofield, Cook, Endeavour, although Cook was initially the most productive.

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.

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.

The North China Plain is an important summer maize/winter wheat rotation area. However, over the years, continued intensive tillage has destroyed the soil aggregate accelerating the mineralization and decomposition of soil organic carbon (SOC), which plays an important role in soil quality, as increased organic carbon storage improves soil fertility and crop yields. Thus, the objective of this study was to explore the comprehensive impact of tillage methods on soil aggregates, aggregate-associated SOC, and carbon sequestration capacity under a regime of straw return. In 2002, we started a 14-year long-term tillage experiment; then in 2016–2017, we tested the following tillage methods, zero tillage (ZT), rotary tillage (RT), subsoiling (SS), and conventional tillage (CT). The results showed that in the 0–10 cm soil layer, tillage methods significantly reduced the proportion of aggregates in the order of 2–0.25 > 5–2 > 0.25–0.053 mm. Additionally, conservation tillage (i.e., SS and ZT) significantly increased the percentage of macroaggregates (0–40 cm) and their SOC content, compared to CT. Additionally, the contribution rate of macroaggregates to SOC was 17.2% and 30.6% higher under SS and ZT than under CT, respectively. Conservation tillage methods improved the carbon sequestration capacity of soil aggregates. Our study provides a theoretical basis for the development of more suitable tillage methods. Furthermore, long-term conservation tillage seemingly protected large aggregates and, SOC, whereby carbon sequestration was enhanced and soil carbon emissions were effectively reduced.

Field experiments conducted over 2 years to evaluate the merits of fractional application of N to hybrid maize unequivocally established its utility in circumventing leaching losses and consequently boosting grain yield. Combinations of fractional application need to be phased to minimize leaching losses and also to correspond to crop needs. Fractional application improved yields even in years when the incident rainfall was evenly distributed.

An experiment in which irrigation intervals for lucerne were dictated by four factors applied to daily evaporation from a Class A pan has been reported by Landsberg (1966). This paper discusses data from a number of subsidiary measurements made during that experiment. An extensive soil sampling programme yielded data on the effects of treatments on soil moisture content, and plant height and per cent ground cover measurements enabled detailed evaluations to be made of crop responses. Both height and ground cover were decreased by soil moisture stress. Relative turgidity was closely related to soil moisture content in the early morning, dry treatments showing more rapid recovery of turgor than those where water was kept at more adequate levels. Radiation utilization by the crop was affected by soil moisture conditions, and also apparently by temperature.

The potential yield of wheat and the physiological basis of yield limitation in the lowland irrigated tropics was investigated in three cultivars planted at five sowing dates. Maximum grain yields were achieved by cultivars that flowered in January when the weather was coolest. The period from sowing to terminal spikelet initiation was similar for all varieties and all sowing treatments. The period from terminal spikelet initiation to ear emergence was increased when seed was sown in late November or early December rather than in October or early November. Manipulation of the sowing date in relation to the choice of cultivar had a considerable effect on grain yield.

H. M. Ishag and O. A. A. Ageeb: Rendimiento del trigo en las zonas tropicales.

Low-temperature stress is an important limiting factor to tobacco growth in early spring of south China. In this study, a low-temperature-resistant agent (LTRA) was employed to examine its ameliorating effect on the inhibition of tobacco growth triggered by low-temperature stress. Results indicated that low-temperature stress of 12 °C for 6 days reduced root number and biomass of tobacco seedling by 27.4% and 24.1%, while treatment with LTRA could recover the inhibitory effect of low-temperature stress on tobacco growth significantly. The content of ascorbic acid and the activities of superoxide dismutase and catalase at low-temperature stress were 65.2%, 53.5% and 32.1% of those at normal temperature condition (26 °C), while the corresponding values with LTRA treatment were 89.2%, 88.9% and 74.2%, suggesting that LTRA treatment could enhance the activity of antioxidant enzyme and the synthesis of antioxidant compounds. Low-temperature stress increased the membrane permeability by 84.8%, while LTRA treatment recovered it by 77.4%. Furthermore, LTRA treatment contributed to increase chlorophyll synthesis and maintain the integrity of tobacco leaf structure. Effective component analysis indicated that the complex of ammonium calcium nitrate and glycine betaine was the main effective component of LTRA in maintaining membrane integrity. Its effective concentration was 1.0 g L−1. The above results suggested that LTRA could enhance the synthesis of chlorophyll, activate the activity of antioxidant enzyme, maintain the integrity of cell membrane, and thus elevate the tolerance of tobacco seedlings to low-temperature stress.

Herbage production from twelve perennial grasses was analysed under two frequencies of defoliation. There were differences in the speed of establishment from seed, Heteropogon contortus, Pennisetum pedicellatum and P. polystachyon being most rapid. Once the grasses were established, the highest yields were obtained from Andropogon gayanus and Brachiaria brizantha and the lowest from Paspalum notatum. Yields were higher at the lower frequency of cutting. There were large differences in production throughout each year, with yields during winter and the dry season (November to April) only about one-tenth of those obtained in the rainy season. A. gayanus, B. brizantha, Chloris gayana and Dichanthium caricosum gave higher yields than other species during winter. Variations in yield between species could generally be ascribed to variations in the extension of leaf area, although some species maintained high net assimilation rates during unfavourable growth periods.

Rubber is usually cultivated for lifespan of 30 years based on the technical feasibility of managing tapping panels. For obtaining early financial benefits, there is a demand for shorter lifespan with intensified tapping. With no research conducted on this line, the present study was focussed to investigate the financial feasibility of shortening the lifespan of rubber trees through lifecycle analyses with three principal scenarios of intensified harvesting, i.e. Intensified Harvesting throughout the Total harvesting Period to obtain a part or full amount of yield lost due to shortening the lifespan (IHTP), Intensified Harvesting only during last 6 Years (IH6Y) and Intensified Harvesting at last ¼ of harvesting Period (IH¼P). In IHTP, intensified tapping to achieve 10–15% of yield loss due to shortening the lifespan was found to be effective to reduce the lifespan even up to 21 years. Market price of rubber and tree stand per hectare were found to be the critical factors determining the best lifespan particularly in IHTP. The best lifespan under IH6Y and IH¼P scenarios was in the range of 19–22 years. Agronomic, environmental and social implications in shortening lifespan of rubber are discussed.

Bush area, shoot number and yield were all strongly and positively correlated in 100 young seedling tea bushes. Clones derived from the bushes exhibited characteristics which were correlated with those of the mother bushes, indicating the usefulness of these observations in the selection of clones for improved performance.

Hypocotyl length in groundnut is a function of sowing depth. In field experiments deep sowing increased the mass of hypocotyl but decreased that of roots, pods and haulm. Few nodules were formed on the hypocotyls of plants from shallow sown seeds (4–5 cm deep). More hypocotyl nodules occurred on Virginia types when deep sown but the number and activity of nodules on the roots decreased. Nodules on the hypocotyl appeared later and fixed less nitrogen than root nodules. Although hypocotyl nodules fixed nitrogen during the later stages of plant growth, this activity could not compensate for the loss in nitrogenase activity due to deeper sowing. Deeper sowing also resulted in decreased pod yields.

Scarcity, lack of access, and ineffective and inefficient use of water in Nkayi District, Zimbabwe, threaten agricultural production. The purpose of this study is to augment understanding of opportunities to increase livestock water productivity (LWP) in Nkayi District by taking into account key differences in the capacities, opportunities, and needs of women and men. There are two important types of female-headed households, de facto and de jure. The results from this study showed that male-headed and de facto and de jure female-headed households share much in common. They all had similar areas of cropland and access to education, finances, veterinary and extension services, and transportation and markets. Households of all types had similar herd sizes. All were desperately poor with incomes much less than a dollar a day. To rise out of poverty, the knowledge, skills and effort of all household heads will be needed. In spite of severe poverty, household heads of all types are literate and have sufficient education that can help enable adoption of intervention options that can lead to increased agricultural production and improved livelihoods. The results also showed that major differences exist in terms of the roles of men and women in ownership, management and decision making related to livestock keeping and animal production. Men clearly dominate in both ownership and decision making even though women play a major role in animal management. Only in de jure female-headed households were women more likely than men to own cattle and goats. They were also more likely to be involved in farming as a primary livelihood activity. Surprisingly, men were more likely to be involved in animal management in these de jure female-headed households. Women were also excluded from water users' and livestock producers' associations although a minority of men was members. By not involving the already-developed capacity of women, the community loses out on a significant opportunity to increase LWP and animal production more widely. Greater inclusion of women in decision making will be an important part of future efforts to improve livelihoods through livestock development.