Callosobruchus maculatus (F.) is a very serious pest of cow pea in storage in Nigeria and many other oountries (Singh, 1977; Tindall, 1983). Damaged seeds are riddled with emergence holes, defaced with egg covers and have reduced viability. Heavy attack causes severe powdering and weight loss. In Nigeria, about 30–60% loss in cow pea is attributed to infestation and damage by bruchid beetles over a 3- to 6-month storage period, of which over 90% is caused by C. maculatus alone (Caswell, 1981).

Rapeseed and mustard cultivars aro morphologically determinate but the growth of the raceme, which is a corymbose type, is indeterminate. On the raceme flower opening proceeds acropetally in a sequential manner with one or two flowers opening each day. Thus there is a considerable time lag between first and last flower opening within the same raceme. In these oil-seed crops, besides leaves both pod wall and stems are photosynthetically active and the share of assimilates contributed by these three organs to the growing seeds has been estimated to be 37, 32 and 31%, respectively (Brar & Thies, 1977). A rapid decline in leaf area during pod filling in rapeseed and mustard (Chauhan & Bhargava, 1984) and rape (Allen & Morgan, 1972) cultivars has been observed. The assimilate supply to the pods developing at different periods may, therefore, differ owing to a decline in the leaf source as well as increasing intornal competition between pods. In winter oil-seed rape (Brassica napus), both mutual competition for assimilates and shading resulting from excessive pod production have been reported to cause heavy seed and pod losses (Mendham, Shipway & Scott, 1981). No information is available for rapeseed and mustard cultivars on how different components of the pod, such as its weight, seed weight, number of seeds and seed oil percentage, change according to their position on the terminal raceme. This information may be useful in deciding the appropriate number of pods on a raceme for optimum yield.

Hagberg falling number (HFN) is used to estimate alpha-amylase activity in wheat grain (Perten, 1964) and it is utilized by flour millers and the Intervention Agencies of the European Economic Community as a grain quality measurement for breadmaking (Anon. 1983). High nitrogen fertilizer application can lead to lodging and can decrease HFN (Brun, 1982). This may result from damp conditions around the ear encouraging germination, and therefore increasing alpha-amylase activity (Stewart, 1984). However, since nitrogen application can also delay maturity, it has been suggested that this influence could maintain high falling number (Anon. 1985). Pushman & Bingham (1976) found that increased nitrogen application decreased alpha-amylase activity, lending support to the previous suggestion, but contrasting with the results of Brun (1982).

The efficient use of fertilizers is important because fertilizers are one of the costliest inputs in crop production. Compared with N fertilizers, P and K fertilizers are subject to less leaching and leave sufficient residues in the soil, which are utilized by the succeeding crop. Thus a knowledge of the residual effects of P and K fertilizers is essential when formulating a fertilizer programme. In order to test the 1st year residual as well as longer-term effects of P, K and farmyard manure (FYM) on tuber yield and soil properties, a manurial experiment was started in 1970 on an acid hill soil at Fagu, Shimla representing the North Western Himalayan hills of India, at an elevation of 2500 m above sea level. The results of the experiment from 1970 to 1975 have been reported by Sharma, Grewal & Singh (1980) and the results from 1976 to 1979 are reported in this paper.