The evolution of the Mediterranean pulses, the common pea (Pisum sativum L.), the faba bean (Vicia faba L.), the grass pea (Lathyrus sativus L.), the lentil (Lens culinaris Medik.) and the chickpea (Cicer arietinum L.), is considered from the points of view of geographic origin and subsequent dissemination. All appear to have originated in the Fertile Crescent, the most significant subsequent spread being to the north of the Mediterranean basin in the case of the common pea and the faba bean and to the east of it in the case of the other three species. The wild progenitor type is known for all species except the faba bean. In the grass pea the extent of divergence between wild and cultivated populations is small, possibly due to its use predominantly for forage and less as a pulse. Considerable divergence has occurred in other species, where use as a pulse is more important.

The potential of winged bean as a multipurpose legume cover crop was shown in field trials by its abundant vegetative growth throughout the growing period of two years. Protein contents of the dry matter of the whole plant, vegetable pods, seeds and tubers were in the range 22–34, 25–30, 32–38 and 16–19%, respectively. In a comparison of two cultivation methods, significantly higher yields were obtained from staked plants than from those grown without supports; protein contents, however, remained constant.

Twenty one genotypes belonging to Spanish, Valencia and Virginia groups of groundnut were studied at Patancheru and a further seventeen at Delhi. Their relative performance based on a large number of characters spanning the entire growth phase was assessed. Nitrogenase activity and nodule mass were measured at three stages of crop growth starting from first flowering, and these two characters alone when measured at 30 days after flowering closely matched the measure of relative performance based on the entire set of characters.

Selected leaves of broad bean on separate plants were supplied with 14CO2, at four stages during development and the distribution of radiocarbon products determined quantitatively 24 h later. These leaves retained substantial amounts of the radiocarbon they fixed initially. In the vegetative phase, basal and middle leaves exported more carbon up than down while the apical leaves exported mainly downwards. During the flowering and pod-setting phase, basal and middle leaves exported carbon equally up and down whereas the apical leaves continued to export mainly downwards. Since assimilates produced by basal, middle and apical leaves at any developmental stage in the life of the broad bean plant were moved both acropetally and basi-petally, it must be concluded that bidirectional transport of assimilates occurred in the stem. During the life of the crop all sources supplied assimilates to all sinks.

Two relay intercropping systems were investigated on an irrigated clay soil: first, wheat with a self-regenerating summer legume and, secondly, grain sorghum with a winter growing legume. A range of summer and winter legumes were evaluated. Phasey bean (Macroptilium lathyroides), a free seeding annual, regenerated vigorously as the wheat matured in early summer; cut twice after the wheat harvest it yielded (including the wheat stubble) 7.5 t ha−1 dry matter. Low seed production jeopardized the regeneration of other summer legumes. Subterranean clover (Trifolium subterraneum) regenerated under the maturing grain sorghum crop as did snail medic (Medicago scutellata) and woolly, pod vetch (Vicia dasycarpa). Together with the sorghum stubble they yielded 5–6 t ha−1 between sorghum crops. The benefits of including self-regenerating forage legumes in irrigated grain cropping systems is discussed.

A field technique to screen large numbers of pearl millet and sorghum lines for seedling emergence through soil crusts is described. Seeds were sown on raised broad beds in an Alfisol field. The beds were smoothed after sowing with a bed shaper. Thirty five mm of water was applied from two parallel lines of sprinklers at a rate of 14 mm per hour. A crust of relatively constant strength in different tests developed as the surface dried out. The crust was broken in the control treatment with a crust breaker. The ratio of emergence under crust to that under control (c/u ratio) was used to classify the test materials.

The results of a two year field study to determine the effect of iron on the yield of maize in the forest and savanna zones of Nigeria have indicated that new and old fields in the savanna, and old fields in the forest zone, require additional iron. The optimum iron requirement for maize in both zones is 3 kg ha−1.

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.

Experimental Agriculture, volume 20, number 2

CONSISTENCY AND CONVENIENCE IN THE CHOICE OF UNITS FOR AGRICULTURAL SCIENCE

By J. L. Monteith

Please note the following correction:

Page 112, line 33

for 101.33 MPa read 101.33 kPa.