Reduction of leaf area in sorghum without tillers (uniculm sorghum) might result in conservation of water at early stages of growth and hence in stability of grain yield under dry conditions. In two experiments in south-east Queensland, Australia, tillers were removed by hand to examine the growth of uniculm sorghum. Tiller removal promoted root development at the flag leaf stage but significantly reduced shoot dry matter and lowered grain yield by about 20% in a wet season. The saving in soil water as a result of tiller removal was relatively small but statistically significant.

Direct belowground nitrogen (N) transfer has often been reported where plants with contrasting nutrients acquisition strategies (N2-fixing and non-fixing) co-occur, and there is still a gap in the knowledge of the extent of this transfer in the top soil under the field conditions. However, assessment under field conditions is challenging. We hypothesized a practical application of the analysis of natural abundance of δ15N supplemented with an isotopic mixing model ‘IsoSource’ to understand the relative direct contribution of N2-fixing Alnus acuminata to wheat intercrop (non-fixing) N isotopic signatures. A field experiment was conducted in an andic soil of high lands in northern Rwanda to quantitatively determine the proportional contribution of nitrogen by Alnus acuminata to wheat vegetative tissue isotope signatures at different distances from the trees (1 m, 3 m, 5 m, and 7 m). The study involved the measurements and analyses of natural abundance of stable isotopes δ15N and isotopic mixing modeling by IsoSource. Leaf samples were collected from twigs of 10 years old Alnus acuminata grown on the terrace-risers, along with soil samples (0–20 cm) and wheat flag leaf samples across terrace at 1 m, 3 m, 5 m, and 7 m from trees for isotopic measurement. The chlorophyll content index of wheat flag leaf at the four points across terrace was estimated by means of SPAD meter 502. The δ15N proportional contribution by Alnus acuminata to wheat was obtained through IsoSource analysis. We noted a significant (p < 0·01) gradient in depletion of wheat δ15N signatures moving further away from the tree line of Alnus acuminata. The wheat at 1 m from the trees exhibited the δ15N values closer to that of the tree, while at 7 m, the crop δ15N signature was significantly different from that of the tree. An isotopic mixing model ‘IsoSource’ indicated that the tree N may have provided 33·6 ± 4·3 % of the wheat intercrop N at 1 m distance from the trees. Therefore, this study shows that the understanding of field-based crop N and nutrient transfer in agroforestry may be enhanced by analysis of the physiological basis of stable isotopes signatures.

Interactions between two contrasting photosynthetic photon flux densities (PPFD) and increasing Ca and P concentrations were analysed in N-fertilised (+N) and Rhizobium-inoculated (+Rh) Phaseolus vulgaris plants grown for 30 days in glasshouses. Plants were grown in sand-filled Leonard jars with 0.9 L N-free for +Rh plants or plus 6 mM KNO3 for +N plants nutrient solution, pH 6.2 in the lower compartment, and were subjected to midday PPFD ≥ 1650 ≤ 1800 mmol m−2 s−1/37±2°C air temperature (HI/HT) or PPDF ≥ 900 ≤ 1200 μmol m−2 s−1/26±2°C air temperature (MI/MT). The nutrient solutions were supplied with 1, 2, 3 or 4 mM P in combination with 1 or 4 mM Ca. Results revealed a 100% mortality of the HI/HT+Rh plants at the juvenile stage of growth. Whereas, all HI/HT+N plants reached the preflowering stage but showed smaller shoot masses, lower chlorophyll concentrations, unusually high chlorophyll a/b ratios and higher shoot nitrate concentrations when compared to values in +N plants grown at MI/MT. Increasing concentrations of P and Ca, or the daily spray of leaves with 2 mM propyl gallate (Pg), did not counteract the negative effects of HI/HT on +Rh and +N plants. Maximum growth, nodulation, chlorophyll concentration and catabolism of ureides in leaves were exclusively observed in +Rh plants grown under MI/MT conditions and supplied with 2 mM P and 1 mM Ca. In contrast, the greater growth of +N plants, associated with higher chlorophyll and nitrate concentrations, took place at MI/MT conditions combined with 1 mM P and 4 mM Ca. Pg further enhanced the growth of MI/MT+Rh and MI/MT+N plants grown at P < 2 mM, at 1 or 4 mM Ca, respectively. At MI/MT, there was a positive relationship between leaf carotenoid concentration and growth of +Rh and +N plants.

Evolutionary studies in the cottons began with the demonstration by Harland that true cottons could be divided into four genetically distinct species, each carrying an internally balanced genotype that was disrupted in crosses with any other. Harland's genetic classification has stood the test of time, and contributes substantially to our understanding of speciation in other genera, as for example, Phaseolus. In addition, it provides a genetic basis for the observations described by Anderson as ‘introgression’.

Studies of cottons found growing wild, and of their relationship to cultivars in the same areas, led to the hypothesis that all true cottons are cultivars, and those now found wild are escapes. This hypothesis, though it led to purposeful exploration of the distribution and relationships of the cottons, was found to be inadequate. A new approach to the relationships of the cottons became possible following Thoday's demonstration of ‘disruptive selection’ in Drosophila. The disruptive situation has been shown to obtain as between cultivars and their wild relatives in Sorghum and in a number of other crop plants.

Consideration of the time scale of agricultural evolution makes it clear that the recent origin theory is untenable, and a review of the status of the ‘wild’ cottons shows that they are adequately accounted for as weedy relatives of the cultivars, descended from common wild ancestors under disruptive selection.

It is concluded that crop plant evolution has gone on very largely within the balanced gene pools which Harland regarded as genetic species.

This article was published with an incorrect Title. The correct title should read:

‘SEED-ORIENTED PLANTING IMPROVES LIGHT INTERCEPTION, RADIATION USE EFFICIENCY AND GRAIN YIELD OF MAIZE (Zea mays L.)’

The original article has been rectified with the correct title and a footnote detailing the error has been inserted in the online PDF and HTML copies.

When wetted overnight by dew, dye spots on a cone-shaped paper ‘sensor’ will spread to an extent which depends on both the duration and the intensity of dewfall. Results from such a sensor have been compared with those from the de Wit recorder. Although only a qualitative assessment of surface wetness is obtained, the paper sensors are cheap and easily replicated, they can be stored for assessment later and they can be made in sizes to suit any particular situation in the field.

Broadsense heritability, and correlations of grain yield and related characters, were estimated in three crosses under two levels of soil fertility, which profoundly affected heritability of height and seed weight. Grain yield exhibited heritability of 51–81%, and in one cross significant heterosis in F2. Amongst yield-related characters only pods/plant and seeds/pod were both correlated to yield, and also lacked negative genotypic correlations with other economic characters. However, direct selection for grain yield was considered more efficient than indirect selection using yield-related characters.

The effects of frequency of potash fertilizer application and of different rates on sweet potato yields were studied in three different cropping systems on Njala upland soils. Fertilizers containing higher K rates (448 kg/ha sulphate of potash) and an N/K ratio of 3:4, gave maximum tuber and low vine yields with low vine/tuber ratios on intensively cropped areas, whereas fertilizers containing lower K rates (112 kg/ha sulphate of potash) and an N/K ratio of 3:1 gave maximum but relatively low tuber and relatively high vine yields, with relatively high vine/tuber ratios on newly cropped areas after seven years bush fallow. Two equal split applications of fertilizer is recommended under the weather conditions prevailing in this part of Sierra Leone.

On a large coconut plantation planted on a deep peat soil in Sumatra, Indonesia, hybrid coconut yields are stabilizing at values well below their potential, even in plots where known production factors have been mastered since the outset: land preparation, water control, and mineral fertilization. To explain this situation, five hypotheses have been proposed. They were tested one by one in field trials. The authors have demonstrated that the main reason for stabilized yields was the Lepidoptera root pest Sufetula spp. and conclude by considering lines of research for controlling this pest in the context of rehabilitation and replanting.

Results of an investigation to select intercrops showed that cotton can be grown with more profit with groundnut or gora paddy than when grown alone. Growing food or cash crops along with cotton enables an early crop to be produced and the practice may help to extend cotton cultivation in Chotanagpur and Santhal Parganas, a potential cotton belt of the future.

This study, designed to investigate trade-offs between forage yields, feed quality and labour use in fitting a newly introduced crop, Lablab purpureus, into an existing farming system, adopted distinct applied and adaptive research approaches. The applied research component compared forage yields, nutrient contents and feeding qualities of L. purpureus harvested at 100, 114, 128 or 142 d after planting in an on-farm trial. The adaptive research investigated how farmers incorporated L. purpureus cultivaton into their farming calendars given the constraints of labour for planting and harvesting.

Harvested dry matter yields from the on-farm experiment were 1.28, 1.98, 1.74 and 1.44 t ha−1. The resultant hays were fed to four groups each of five Bunaji lactating cows in an on-farm feeding trial over a 10-week period. Ranking the various harvests for yield, the hays for feed value, animal responses to the feed consumed and the quality of animal products on a linear scale (1 to 4) to estimate a composite utility index, showed that harvesting at 114 d after planting gave the most desirable overall benefits.

The survey for adaptive research showed bimodal rainfed and irrigated cultivation patterns for L. purpureus. Peaks were observed in September (31% of farmers) and November (24%) for planting, and in December (39.4%) and March (15%) for harvesting. Forage yields were, however, highest for the 3% of farmers who afforded labour to plant in July and harvest in October. The lack of congruence between highest forage yield periods and the peaks of cultivation of L. purpureus by farmers in the study area was mostly explained by very significant differences in the cost of hired and household labour in different months. Thus, socio-economic and cultural factors, including stakeholders' participation, need to be considered along with applied research results when recommending forage species for farmers' adoption.

Suggested rules are given for the presentation of numerical data in a scientific agricultural journal. These are that all tables of numerical results should be sufficiently clear to render unnecessary any reference to the accompanying text; and that treatment means (and other statistics) should always be accompanied by their standard errors, rather than by least significant differences or by asterisks showing the results of significance texts. Examples are given of correct and incorrect presentation of results, and the graphical presentation of results is also discussed.

Gac is a dioecious tropical and perennial climber. The fruit is a rich source of carotenoids and is used in traditional cuisine and medicine. Improving propagation methods using simple techniques would increase production and improve conservation in regional areas. This study evaluated temperature requirements for seed germination, the use of rooting hormones to strike female cuttings and the grafting of female scions onto seedling rootstock. Seed germination was optimised between 25 and 35 °C, with a maximum germination percentage of 91% at 30 °C. However, increasing storage time from 6 to 18 months under laboratory conditions (21 ± 1°C and 60% relative humidity) reduced germination and this was associated with seed weight loss, highlighting the need to develop storage guidelines, particularly for the higher temperature and humidity conditions where Gac is grown. Survival of softwood cuttings was improved from 53 to 77% with indole-3-butyric acid (IBA) (3–5 g/L) and semi-hardwood cuttings did not require IBA treatment. Both splice and wedge grafting techniques achieved a survival rate > 53% and with the youngest rootstock (4 and 8 weeks) this increased to > 85%. Further work could investigate the production potential of crops using cuttings and grafted plants.

The genotypic and phenotypic correlations and path-coefficients were studied in two different environments, using twenty fodder genotypes of cowpeas. Among quantitative characters, leaves/plant, branches/plant and stem girth were highly correlated with both green and dry matter yield, whereas among quality characters, total protein (per cent) showed significant association with digestibility (per cent). Based on path-coefficient analysis, leaves/plant and protein (per cent) were found to be the most important component characters. These two characters were also highly correlated at both the genotypic and phenotypic level and, therefore, selection based on leaves/plant is likely to be useful for simultaneous improvements in yield and quality of fodder in cowpeas.

Meloidogyne paranaensis is responsible for considerable losses in coffee production. Because of the distribution of this species in the main Coffea arabica producing regions, there is a need for management practices to ensure the sustainability of coffee production. In this work, we evaluated the agronomic performance of resistant clones of the Conilon coffee cultivar Vitoria Incaper 8142 in areas infested by M. paranaensis in the west region of Minas Gerais, Brazil. Clones 2V, 3V, and 6V presented the lowest number of nematodes per gram of roots and were considered resistant to M. paranaensis. All other clones were considered tolerant to this nematode, and one had good vegetative growth but allowed nematode reproduction. Clones of Vitoria Incaper 8142 of C. canephora represent an alternative to coffee production in areas infested by M. paranaensis including areas traditionally cultivated with C. arabica.

In Brazil, high-yield soybean [Glycine Max (L). Merrill] – corn (Zea mays L.) double cropping system might be nitrogen (N)-limited and additional N fertilization can be beneficial. Early application of N in soybean reduces the symbiotic N fixation (SNF) efficiency and/or establishment. One alternative to avoid SNF impairment is to apply N between the beginning pod (R3) and seed-fill (R5) stages through the use of controlled release fertilizers. In this study, N was applied at 50 kg ha−1 as common urea (CU) or controlled release urea (CRU) with different lag periods until N release starts (30 days, 60 days, or 1:1 mix of both lag times) in a randomized complete blocks design with six treatments and four replicates under tropical and subtropical conditions. CU was applied after soybean emergence (VE) or at the beginning pod (R3), and CRU only at VE. Using urea labeled with 15N isotope, we analyzed the N source used by soybean (fertilizer, soil, or SNF) and SNF parameters. On average, CRU – 30 days, CRU – 1:1 mix (30 + 60 days) and CU applied at the R3 stage increased grain yield by 9.2% (354 kg ha−1) compared to the control. N derived from all fertilizer treatment were almost 35 kg N ha−1, a high N recovery efficiency of 68%. The SNF was not impaired by CU and CRU and accounted for 71% (220 kg N ha−1) of total N uptake. In the conditions of the experiments, fertilization of 50 kg N ha−1 as CRU was shown to be effective to supply N in late soybean demand (R3 stage), increasing yield without damaging the SNF process in high-yield environments.