A NPK factorial experiment was conducted during two successive cropping seasons to study direct and residual effects of various treatments on the flower initiation and yield of soybeans. Plants were slower to reach the maximum flowering stage in the year of fertilizer application than in the following year. During the first year potassium in association with phosphorus delayed the flower forming process, whereas potassium alone hastened flowering in the second year unless associated with a high dosage of nitrogen. All the treatments gave far greater yields in the first season, suggesting that fertilizers should be applied during every cropping season. Nitrogen and phosphorus at 20 pounds of N2 and P2O5, per acre gave the biggest yields, but potassium failed to show any response. The residual responses to potassium and phosphorus during the second year were significant but not to nitrogen.

COCA (highland), TZPB (lowland) and COCA x TZPB maize varieties were tested at Bambui Plain (1330 m) and Ekona (550 m). Leaf blight and rust were controlled chemically with Dithane-M45 and Benlate, and their use significantly increased the yields of COCA when grown in lowland environments, where it does not possess resistance to lowland leaf blight (H. maydis) and rust (P. polysora); yields of TZPB were similarly increased in highland areas, where it is susceptible to highland leaf blight (H. turcicum) and rust (P. sorghi). COCA x TZPB was intermediate in resistance to both diseases at the two locations.

Heritability of four quantitative characters in two crosses of Brassica campestris L. was found to be high. Dominance was detected only for plant height at heading time in both the crosses, and for sowing-to-heading period in Toria-TP × Toria-7. Transgressive segregation was expected in the segregating progenies for all the characters. Epistasis was complementary in all characters except in plant height at ripening time, where it was of the duplicate type. Additive × dominance type of epistasis was most significant and was present in most of the characters. Genes for most of the characters were linked with a major gene for seed colour (Rr). Yield was genetically correlated with the four quantitative characters studied.

An experiment was carried out in the glasshouse to determine the availability of P, and utilization of added phosphate fertilizers from three fertilizer materials, applied by two different methods to sugar cane grown in four diverse soil systems. Phosphorus was applied at the equivalent rate of 175 pounds P (400 pounds P2O5) per acre. A larger response from added P in terms of plant yields was obtained from an aluminous ferruginous latosol and least from dark magnesium clay. Differences in yields of sugar cane were evidently associated with differences in P content in the cane plants and, in certain cases, with a reduction in Al content in plant tops, and the less soluble superphosphate increased yields more than the highly soluble NH4H2PO4. Phosphate fertilizers applied as foliar spray greatly increased the P content in the plants, and plants contained twenty times more P when sprayed with NH4H2PO4 than when the same fertilizer was applied to the soil. However, increased P content in the plants did not necessarily indicate that the P was translocated within the plants or that the added P participated in metabolic processes. The evidence indicated that in soils where the ‘A’ value was high the P status of the sugar cane tops was not correspondingly high.

Application of zinc to six high-yielding rice varieties in calcareous soils produced significantly higher grain yield and interactions between varieties and Zn levels were significant. Yields of varieties IR 20, Jaya, Sita and Jayanti at 2.5 and 5.0 ppm Zn were similarly affected, but Archana produced significantly higher grain yield at 5 ppm Zn than at 2.5 ppm. Effects of Zn on straw yield were similar. Zn application invariably resulted in a higher Zn concentration in plants at all stages of growth and in grain in all varieties. Maximum Zn contents were observed at the tillering stage and minimum at harvest.

An on-farm study was carried out at 17 different sites within the Western Hills of Nepal during the spring and summer seasons of 1993 and 1994 in order to monitor the plant population density dynamics of the maize (Zea mays L.) crop under farmers' management. Five farmers were selected randomly at each site and a 20-m2 plot was demarcated just after maize sowing. The maize stands within the 20-m2 plots were first recorded 20 d after sowing, and then at 10-d intervals until harvest. Farmers were allowed to perform all cultural practices on their own. On average, the initial plant stand across all locations and over two seasons was 69 100 ± 1800 plants ha−1, which resulted in 37 300 ± 1700 plants ha−1 at harvest, a 46% reduction from the initial stand. At most locations, the population declined by 30–40 × 103 plants ha−1 between emergence and harvesting and in no cases were the recommended plant populations achieved at harvest. Populations varied across sites and seasons. The rate of population decline was higher in the low and mid hills compared to high-altitude areas. Thinning which is carried out between 30 and 60 d after sowing at most sites was the major cause of population reduction, and delay in thinning was intended to increase fodder production from the thinned maize. In addition, the removal of barren plants at the silking stage and of smutted, lodged and damaged plants attributed to about 12% of total reduction in plant population. The larger the initial stand, the larger was the proportion of barren plants to be removed. No clear relationships were observed between soil fertility and final plant stand at harvest.

A series of N × P field experiments with irrigated rice, conducted over the period 1958–1962 on the same plots on alluvial soils considered representative for most of the bottom ‘fadama’ land in Niger and Ilorin Provinces, Northern Nigeria, showed small increases with medium dressings of P2O5 and large responses with high dressings of N. The N responses showed considerable variation between soil types and years. The variation between soil types was attributed to different cation exchange capacities, which resulted in NH4′ leaching from the root zone at different rates. The variation in N responses between years was probably due to different physiological timings of the top dressings. Results of chemical analyses of straw and grain samples of the 1961 crop were used to estimate the percentage of N and P2O5 recovered by the crop with the various treatments over the untreated plots in the previous years of the experiments on two soil types. The recovery percentages for the different levels of N on the clay ‘basin’ soils were moderate, about 18 per cent, whereas those for the sandy ‘levee’ soils were lower, averaging only 9 per cent. Recovery of P2O5 varied from good at medium N levels (14 per cent) to moderate at high N levels (9 per cent) on the basin soils. Recovery of P2O5 on the levee soils was poor. The utilisation of the recovered N (75 lb paddy/lb N) and P2O5 (42 lb paddy/lb P2O5) was very good for N and fair for P2O5.

The OxG hybrid bunches contain more parthenocarpic fruits (PF) than normal fruits (NF) and present problems of development and ripening due to either an asynchronous opening of flowers or insufficient pollination. The objective of this study was to compare the effect of α-naphthaleneacetic acid (NAA) and gibberellic acid (GA3) in the induction and development of PF and NF, the fatty acid profile (FAP), and the oil potential in the ‘Coari x La Mé’ oil palm hybrid. NAA and GA3 induced parthenocarpy in the fruits and did not alter the FAP of the mesocarp oil. The commercial dose of pollen (0.9 g talc + 0.1 g pollen) resulted in increased bunch weight (BW) (20.8 kg) and lower percentage of PF in the bunch (65.4%). The most effective hormonal doses to induce the formation of PF in the bunch were NAA 300 and 600 mg L-1. GA3 alone or in mixture with NAA increased the percentage of PF but did not increase the BW, indicating that GA3 had no synergistic effect on BW. The NAA applications represent alternatives to complement assisted pollination of OxG hybrids to increase bunch production and oil yield.

A field experiment to study the response of pop corn (Zea mays Everta) to various levels of nitrogen and plant population was undertaken at the Research Station, Bajaura (HP) during kharif 1974 and 1975. Increases in nitrogen level from 0 to 60 kg N/ha increased grain yield significantly by 54·8%, but yield differences between 60 and 90 kg N/ha were non-significant. Various plant densities did not affect yield significantly. Yield-contributory characters were significantly influenced by treatments and were interrelated with yield under the influence of nitrogen and plant population levels.

Substantial improvement is reported in a quality measure, large seed size, after only one generation of mass selection from a bulk ‘Chalimbana’ population of Zambian land races of the inbred species Arachis hypogaea L. There were large positive correlations between seed size as planted and the subsequent mean size harvested. Large seed also tended to produce an increased proportion of 2- rather than 3-seeded pods, further improving both crop uniformity and quality. Total yield was unaffected, or possibly even slightly enhanced, by planting larger kernels. The circumstantial advantages of mass as opposed to pedigree selection methods are discussed.