The response of cassava to CCC was investigated by applying concentrations of 0, 500, 1000, 1500 and 2000 ppm twice or four times as a foliar spray, which resulted in a significantly greater tuber yield than the control with most marked effects at the final harvest. CCC at 1500 ppm, applied four times at various growth stages, gave the best increase in tuber yield. Application of CCC tended to cause greater RGR and dry matter content (percentage) of tubers.

Mechanical disintegration seems to be the most effective way of damaging the cells in potato tubers so that their juice can be expressed. If disintegration is too intense the pulp is intractable; a grater makes a uniform pulp with suitable texture. With existing continuous equipment it is necessary to press in two stages to get to 40% dry matter and further batch pressing is needed to get to 50%, but experience suggests it should be possible to make a press that would press to > 50% in one operation. Much less energy is needed to press out water rather than evaporate it, but about one-sixth of the tuber dry matter and more than one-half of the N is in the juice.

Mechanically dehydrated potato pulp containing up to 50% dry matter was stored, without visible deterioration, for up to 25 weeks after treatment with at least 0·3% of propionic acid. Wetter pulps required more acid for satisfactory preservation. Thorough mixing was important if maximum storage periods were to be achieved. Ammonia was less satisfactory as a preservative. No visible deterioration occurred while ammonia vapour was present, but bacterial growth was still found even after the addition of about 0·7% ammonia to pulp containing 40–45% dry matter.

Despite large visual differences in size and form of shoot and root systems of young clonal plants and of older seedlings, there was no convincing evidence that tea plants, brought into bearing by pegging, are necessarily more susceptible to water stress than similar plants that have been pruned, though the sap tension in pegged plants of one clone was often greater than in similar pruned plants. Further studies are needed to show whether this is the case in drier areas, but differences in responses to dry conditions by individual clones appear to be of greater significance.

The yields of extractable protein, and its rates of production, were measured with seven crops given large dressings of nitrogen, which produced lush plants with small fibre to juice ratios, increased the nitrogen content (as percentage of dry matter) in five species, improved the extractability of protein N in three, and gave significant increases in both dry matter and protein yields of non-legumes. However, yields were affected more by climate than by the N fertilizer. It is felt that non-legumes given large dressings of fertilizer N, as well as leguminous fodders, could be used efficiently if their excess protein was extracted and used for human consumption.

The stabilities of plant height and yield for rice varieties grown in Sri Lanka were calculated by regression analysis. High yields were produced by both stable and unstable varieties in the wet season, but in the dry season high-yielding varieties tended to be of above-average stability. The yield of the newer, shorter varieties exceeded those of older varieties except at low nitrogen levels, and the new varieties were of above-average stability.

The relations between sugar content and certain features of growth were followed in 16 sugarcane varieties during two crops. High sugar content was promoted by the absence of tillering during cane elongation, by a high leaf blade to joint weight ratio, by a long phyllochron, and perhaps slightly by a long life span of leaves. To combine high yield with high sugar content it is important to have a high tiller number early in growth, which appears to be promoted by delayed onset of cane elongation, small initial leaf size, and an upright leaf habit. To combine a small initial leaf size with a high leaf blade/joint weight ratio during elongation requires a large increase of leaf size during growth.

The important interactions in a 2-year maize trial were population × location, location × year and population × year × location, and our analyses suggest that eight locations, two years and three replications will allow the detection of a 5% differential in yield. The most effective way of obtaining the true value of a variety is by increasing the number of years, and the least effective is by increasing the number of replications. Since locations can be effectively substituted for years, increasing the number of locations will expedite the release of improved cultivars.

The growth and development of a short-season sweet potato (Nemagold) and a long-season cultivar (White Maltese) were compared quantitatively in sub-tropical Australia and also with growth data for Nemagold in a temperate environment. Total and storage root dry matter production (DMP) followed autocatalytic equations, with similar whole plant DMP from planting to week 25 for both cultivars but plateauing (at 90% of asymptotic weight) at week 23 for Nemagold (448 g) with favourable temperatures and at week 38 for White Maltese (813 g) when temperatures were unfavourable. Storage root DMP of Nemagold plateaued at week 23 (246 g) and at week 36 (219 g) for White Maltese. Data are given on other attributes and on phasic development.

Trials on leaf abscission of cassava led to the conclusion that the leaf lamina is necessary, and must receive light, to prevent abscission of the petiole. The abscission rate of old leaves is increased by the presence of an active apex, but is not affected by the carbohydrate requirements of the roots.

The effects of populations of 33,000–250,000 plants/ha on growth and grain yield of two cowpea genotypes of bush growth habit was studied in lowland Papua New Guinea. The optimum economic seed rate seems to be 100,000 plants/ha; increasing the plant population decreased pods/plant and lateral branch development, but increased seed number/pod. Genotype UV.53 yielded more than UV.19 due to a combination of all three yield components, and a large dry weight. Growth analysis showed that treatment effects were mediated by differences in growth between 8 weeks and harvest.

Phenotypic correlation coefficients of flag leaf blade length, breadth and sheath length with plant height, grain yield and its components were computed in four wheat varieties and their ten F2 crosses. Flag leaf sheath length was positively related to plant height, grain yield and its components in almost all the populations, but little or no such relation occurred with flag leaf blade length and breadth in most cases. The data suggested the possibility of selecting plants with longer flag leaf sheaths, with obvious yield advantage.

Post-anthesis trends in yield and forage quality of dry matter in components of the maize shoot were studied in experiments with barren and fertile plants grown at 10 plants/m2. In fertile plants, which had a maximum shoot DW 6 or 7% higher than barren ones, the stems (including leaf sheaths) yielded 5 t/ha (42% shoot DW) 30 days after flowering, declining to 3·5 t/ha (26% DW) at final harvest 60 days later. During this period the ear increased by more than 4 t/ha, from 23 to 50% of shoot DW, whereas in barren plants there was little change in DM distribution, with the stem representing about 48% shoot DW, leaf and husk together 40–45% and the ear (rachis only) less than 10%. DM percentage of shoots was similar in barren and fertile plants until maximum DW was attained about 60 days after flowering, after which fertile plants dried more rapidly. In vitro dry matter digestibility was as high in barren as in fertile plants, and the analytical data on forage quality do not suggest that it was positively associated with grain content.