The effect of available water on yield (e.g. Waring, Fox and Teakle, 1958) and of nitrogen on yield and quality (e.g. Waring and Teakle, 1960) have been examined for wheat grown on black earths of the Darling Downs in Queensland. However, the joint effect and individual contributions of nitrogen and water to this effect in the field appear to have been neglected. Further, the condition known as mottled wheat, described by Wood (1960), is an important problem in the wheat industry, and it was felt by the authors that this condition was the result of a water-protein yield complex. It was therefore decided to examine the effects on yield, total protein and mottling of applications of nitrogen and water in a soil where these were deficient.

In a two-year study the yields and water use of corn were studied under four planting patterns, with different soil moisture regimes and organic (paddy straw) mulches. Normal planting and irrigation resulted in higher yields and lowest water use efficiency, while double file planting in deep furrows (rafter method) gave greatest efficiency of water use but with a slight decrease in grain yield. Mulches improved water use efficiency by 50–60% and reduced irrigation requirements by four to six irrigations. Under limited moisture conditions a combination of these practices is likely to reduce irrigation requirements by half and to double water use efficiency.

Yields are presented for a 54-week cutting experiment (1962–3) in which coastal bermuda (Cynodon dactylon sp.), pangola (Digitaria decumbens) and guinea (Panicum maximum) grasses were subjected to three cutting heights (1, 3 and 6 inches), four cutting intervals (1, 3, 6 and 9-weeks) and four nitrogen fertilizer regimes (0, 8, 16 and 32 cwt sulphate of ammonia per acre per annum). The results indicate that coastal bermuda and pangola grasses will tolerate severe cutting but not guinea grass. The highest dry matter yields were obtained from guinea grass, at 16½ tons/acre. Whereas the highest yields of coastal bermuda and pangola were 12½ and 12 tons/acre respecitvely. In the absence of measures of nutritive value it is impossible to say which is the best management system to adopt, but the facts presented may help to determine management practices.

The effects of phosphorus fertilizer and the insecticide carbofuran on the growth and N2-fixation of Azolla pinnata and on the growth, grain yield and nitrogen uptake of intercropped rice were examined in a wet and a dry season. Treatment with phosphorus or carbofuran increased the biomass of Azolla and the amount of nitrogen fixed (nitrogen yield) in both seasons, but the response was much better in the dry season. Azolla inoculation at 1.0 t ha−1 resulted in a greater bio mass and nitrogen yield than inoculation at 0.5 t ha−1. In the dry season, a combination of phosphorus and carbofuran enhanced the growth and N2-fixation of Azolla more than either treatment alone. Carbofuran treatment slowed the rate of decomposition of Azolla, particularly in the dry season. The plant height, leaf area index and dry matter production of rice at flowering time were increased in the plots treated with phosphorus or carbofuran in the wet season and these treatments increased rice grain yield and nitrogen uptake in both the wet and dry seasons.

We evaluated the effects of cattle manure and inoculation with arbuscular mycorrhizal fungi (AMF) in maize plants growing in a semiarid area of Brazilian north-east in 2012 and 2013. Three isolates of AMF (Acaulosporalongula URM-FMA 07 and URM-FMA 03, Claroideoglomusetunicatum UNIVASF 06A) were used, with or without the application of cattle manure, during two growing cycles. In the first year, significant effects of inoculation were detected for straw yield only when the manure was applied. In the second year, there was an interaction between fertilisation and inoculation for plant height and grain yield, with the highest values in the fertilised treatments. Inoculation with A. longula demonstrated that mycorrhizal inoculation in field-grown plants could be an alternative management for improving plant growth and grain yield, reducing the use of cattle manure. The AMF sporulation and mycorrhizal colonisation were improved after inoculation, and A. longula URM-FMA 07 increased sporulation by more than 15 times while inoculation with C. etunicatum increased sporulation by more than 3 times. The mycorrhizal inoculation is a management practice that can be useful for recovering or maintaining AMF infective propagules in soil, showing potential to be used in large-scale field conditions in Brazilian semiarid. Although mycorrhisation presents high agricultural relevance due to benefits promoted to the soil and plants, the knowledge about the factors influencing the interactions among microorganisms, soil and plants need to be broadened aiming to achieve successful crop management in semiarid regions.

Oil palms with white stripe have greatly reduced yields. In the chlorotic areas of the leaflets, columnar palisade cells fail to develop and there is a reduction in air-space volume of the spongy mesophyll. Leaf area and photosynthetic activity are also reduced. Recovery of palms showing symptoms was spasmodic. The condition is discussed in relation to boron, to N/K ratio, polyphenols and availability of photosynthate.

The effects of component population, rhizobial inoculation and applied nitrogen on the efficiency of phosphorus utilization in maize/mungbean intercropping were examined in two experiments. The efficiency of phosphorus absorption decreased by between 5 and 43% in maize and by between 31 and 58% in mungbean as a result of intercropping. The overall efficiency of phosphorus absorption in intercropping decreased with increasing nitrogen level but a parallel increase in overall conversion efficiency maintained a constant and large land equivalent ratio (LER) up to the highest level of nitrogen. The increase in LER over unity, however, was due primarily to the greater total absorption of phosphorus by maize and mungbean together in intercropping compared with that when they were grown in pure stands.

The use of a durometer to assess hardness of onion bulbs is described, and compared with the use of a tensile testing machine. Results from the two tests were closely correlated, and significant varietal differences were detected in bulb hardness by both machines. The durometer is of particular value because of the simplicity and non-destructive nature of the test procedure.

In 1968–9 and 1970–1 small-scale experiments were set up on over a hundred farms in Barbados, simple enough for farmers to carry out with a minimum of supervision. Results were obtained from more than 70 in each year. NK fertilizing gave no increase in yield in 1968–9, but a significant increase of 800 lb per acre in 1969–70. In each year NPK gave a highly significant increase of 1000 lb per acre. There was also a general increase in yield with increasing rainfall up to about 40 inches during the growing season and with closer than normal spacing especially under conditions of low rainfall. Planting later than usual led to marked decreases in yield.

Since the profitability of the geranium crop depends to a great extent on the total yield of oil per acre, methods of increasing this yield are of prime importance. Two trials were laid down to determine the responses to nitrogen, phosphate and cutting at various times during the year. Phosphate increased total weight of green material, nitrogen had little effect, and neither significantly affected the yield of oil per ton cut. Time of cutting influenced both oil and green material yields. Climatic factors producing higher yields of green material had the opposite effect on yields of oil per ton of material cut, and vice versa. Fertilizers had no discernable effect on oil quality, but there was an appreciable difference between oil produced after wet and dry periods.

Ten planting dates were selected at weekly intervals for the purpose of determining the optimum planting date for two late maturing sorghum (Sorghum bicolor) cultivars in the 1995 and 1996 cropping seasons. Both the floral characteristics and the ultimate grain yield were affected by variation in planting date. The highest grain yield for each cultivar (977 and 958 kg ha−1 for Janare and Farin Dawa respectively in 1995, and 975 and 955 kg ha−1 respectively in 1996) resulted from planting delayed for exactly 51 days after the onset of the rains. Consequently, 10–12 June appeared to be the optimum planting dates for sorghum in the area. A comparison of the result with previous work done in the same ecological unit revealed that delaying planting until 10–12 June increased grain yield by about 25–27 kg ha−1. The effects of the characteristics of the onset of the rains on the optimum planting date have been discussed and the implication of the study for traditional agricultural practice in Nigeria has also been noted.

A glasshouse was built over an established tea crop in Malawi, and the internal air temperature was controlled by manual regulation of the heating, cooling and ventilation rates of two domestic air conditioners. When the inside environment was carefully matched to conditions outside, the glasshouse had only a minor influence on the tissue temperature, stomatal behaviour, leaf water potential and shoot growth of the bushes. The system could be a useful aid to experimentation on the temperature and water relations of field crops in the tropics.

Beans collected from immature pods of cocoa progency C77 × C23, as early as 15 weeks after pollination, successfully produced seedlings as vigorous as those from mature ripe pods. Seedlings produced by beans from 21-week-old pods were the most vigorous, with vigour based on the integral of all measured growth parameters (leaf number, leaf area, seedling height, girth and root weight). There were close correlations between these growth parameters on the one hand and bean maturity and seedling age on the other, the relations with the former being curvilinear and with the latter linear. Seedling age and bean maturity accounted for between 87–99 and 42–96 per cent respectively of the variations in growth parameters. Multiple regression equations are presented for quick estimations of leaf area.

To investigate seasonal effects on nodulation of legumes during an English summer, plants of Pisum sativum and Phaseolus vulgaris were sown in pots in the open at intervals of 14 days between March and July and the pots were watered on all days when rain did not fall. The weight of nodules per plant varied significantly between sowing dates and showed seasonal trends in both legumes, but in different directions. In P. sativum nodulation was at a minimum at the midsummer sowing date but with P. vulgaris the mid-summer sowing gave maximum nodulation. The data are further analysed in terms of number and size of nodules, and nodule weight as a percentage of plant weight.

In Queensland it is standard practice to burn sugar cane before harvest, but incomplete burns are common, due to the lush condition of the crop and the occurrence of weeds. Experiments conducted over seven seasons to dry out foliage of both weeds and cane, using bipyridylium desiccants, showed that paraquat was consistently more effective than diquat. After treatment of cane foliage, several days were necessary for fully effective desiccation, during which time a slight drop in sugar content could usually be detected. It is practical to spray cane leaves in the outside rows, adjacent to headlands (where weeds normally thrive). Treatment of this peripheral zone could affect no more than 10 per cent of a cane stand, and any loss of sugar would usually be more than offset by the benefits of desiccation, viz: a cleaner burn, quicker cutting, less trash, and fewer penalties.

Field experiments are commonly designed in blocks and there are sound reasons for using them, for example, control of unwanted environmental differences and administrative convenience. If used, they should be chosen to correspond to perceived differences in the site or to simplify farm operations and not merely to conform to statistical desiderata. Thus, it is not essential that each must contain one plot for each treatment, though there are advantages if they do. Some of the consequences of using other block sizes are examined, it being borne in mind that modern computer packages will perform most of the tiresome arithmetic. The effectiveness of blocks is considered and it is noted that they sometimes do harm rather than good. The analysis of variance is explained in terms of strata as used in many modern computer programs and is extended to include the recovery of information and resolvability. Recommendations are made as to randomization.

Glasshouse and field trials have been used to assess the effect of applying calcitic lime and gypsum on haulm weight, pod-filling and kernel yield of groundnuts grown in soils of Northern Malawi. Incorporation of lime prior to planting and topdressing gypsum at flowering both rectified poor pod-filling and improved kernel yield. Gypsum decreased haulm weight and usually produced lower overall kernel yield than lime. The relative merits of lime and gypsum application are discussed, together with the need for supplementation by phosphorus and sulphur.

Irrigation responses of three locally adapted onion cultivars were studied in drainage type lysimeters and under field conditions on a deep sandy loam soil, free of salinity problems, at Maradi in Niger. Evapotranspiration (Et) was established by the water balance method, and used to establish the rate of water use. The peak rate of water use was 7.5 mm per day during the bulb formation stage. Irrigating onions when the available soil moisture to a depth of 20 cm had been depleted by 40% increased the yield more than irrigation at 60 or 80% depletion. The mean yield from plots receiving frequent irrigation was 33 t ha−1.

Evapotranspiratión de la cebolla en el sahel nigeriano

The effects of four calcium-containing materials on soil pH, nutrient availability and productivity of groundnut (Arachis hypogaea) on acid soils were studied in field experiments conducted at the Horticulture Research Centre and the Makoholi Experiment Station in Zimbabwe. The materials were calcitic limestone, dolomitic limestone, gypsum and single super phosphate.

Application of dolomitic or calcitic limestone significantly increased soil pH and exchangeable calcium and magnesium levels, whereas gypsum and single super phosphate did not. Application of 4000 kg ha−1 calcitic limestone increased calcium levels by up to 125% at the Horticulture Research Centre and 872% at Makoholi Experiment Station, while dolomitic limestone increased magnesium levels by 183% and 473% at the Horticulture Research Centre and Makoholi Experiment Station respectively. Combining gypsum and single super phosphate with 2000 kg ha−1 calcitic or dolomitic limestone did not affect soil pH differently than the limes alone. Furthermore, gypsum and single super phosphate applications on their own had no effect on pH, calcium and magnesium levels. The phosphorus, potassium and nitrogen levels were not significantly affected by the calcium-containing materials.

Application of either dolomitic or calcitic limestone significantly improved productivity of groundnut, with 4000 kg ha−1 calcitic limestone producing the largest increases in kernel yields at both sites. Yield responses to gypsum were not significantly different from the control treatment. Despite the notable changes in soil chemical properties observed at both sites, deficiencies of nitrogen, phosphorus, potassium, calcium and magnesium, coupled with low pH per se, remained the primary reasons for poor growth on the acid sandy soils at both sites.

Changes in plant dry weight and nitrogen content of Trifolium semipilosum cv. Safari and T. repens cv. Grasslands Huia were monitored when the root systems of effectively nodulated 28-day-old plants were exposed to a range of constant and diurnal temperatures for 21 days. Nitrogen fixation was more sensitive to high root temperatures than was dry weight accumulation, and T. semipilosum was relatively more tolerant of high root temperatures than T. repens for both dry weight and nitrogen content. The optimum temperatures for dry weight yield and nitrogen fixation (≡nitrogen content) were similar (21–23°C) for both species.

Our data suggest that growth and nitrogen fixation in T. semipilosum are more tolerant of short-term exposure to increase in root temperature than in T. repens. In addition, both species accumulated more dry matter and fixed more nitrogen when night temperatures were reduced from either 30 or 35°C to 25°C. The increase was greater with T. semipilosum and may be a major factor in its adaptation to the humid subtropics and cooler (elevated) tropics.