Peanuts (Arachis hypogaea L.) which are commonly grown in intercropping systems often suffer from shading caused by the associated crop. Through this study an attempt has been made to estimate the effect of different levels of shade at different growth stages on crop yield. Field experiments were laid out during monsoon and winter seasons of 1985 and 1986 by creating artificial shading up to 25 and 50 per cent of the day/natural light at flowering‐pegging, pod filling and maturity stages of a Spanish bunch type peanut. Dry matter production has shown linear response to light intensity and due to 50 per cent shading it was reduced by 55 per cent. Vegetative growth rate during pod filling stage was very poor as a result of increase in shading at this stage. In shaded plants the nodulation was less and some reduction in chlorophyll content was also observed. However, oil content in kernel was not affected by shading. Shading caused significant reduction in pod number and kernel weight and thus there was decrease in pod yield. Flowering to pegging and pod filling stages seemed to be sensitive to shading while increase in shading at maturity stage did not cause any reduction in yield. It could be possible to obtain about 90 per cent pod yield by avoiding shading during flowering to pegging stage (45 DAS).

SUMMARYField experiments were conducted during the two monsoon seasons of 1985 and 1986 at Kharagpur, West Bengal, to investigate the effect of pigeonpea cultivars and their planting pattern on the performance of a groundnut–pigeonpea intercrop. In intercropping the crops were also sown at 100% population of their sole crops. Groundnut plant growth and development was affected by intercropping with pigeonpea and the decline in pod yield ranged from 7 to 50% of the sole crop yield. The compact, short-statured and short duration pigeonpea cultivar, ICPL87, intercepted only 50% of the incoming solar radiation as against the 70% intercepted by LRG30 at the peak vegetative stage. The significantly higher groundnut yield (48%) obtained from the intercrop with the former pigeonpea cultivar as compared to the latter justifies the belief that the performance of the groundnut was light-related. This was further confirmed when the light interception by pigeonpea was reduced by increasing the row spacing from 90 to 150 cm and there was a consequent increase in groundnut yield. The cultivar and row arrangement of pigeonpea that allowed equal utilization of light by both crops gave increased productivity.

Eight genotypes of groundnut and two of pigeon pea were evaluated in intercropping at the Indian Institute of Technology, Kharagpur, during the monsoon and winter seasons in 1985 and 1986, to identify plant characters associated with high yield in intercropping. The pod yield of groundnut decreased when intercropped with pigeon pea, the extent of the decline differing with groundnut and pigeon pea genotypes. The reduction in groundnut pod yield and the degree and duration of shading was less when grown with pigeon pea type ICPL87 than with LRG30. During the monsoon, pod yield among intercropped groundnut genotypes ranged between 47 % and 88 % of their yields under monocropping because of differences in growth pattern and duration (90-125 days). The groundnut type most suitable for intercropping had early vigour, early maturity and high partitioning and pod growth rate. However, variation in pod yield among groundnut genotypes was not observed during the winter season because they showed less variation in duration and growth and there was less shading by the associated pigeon pea. INTRODUCTIONMATERIALS AND METHODS

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Intercropping has been recognized as an important farming practice, particularly under rainfed conditions, for its greater stability in production, equal distribution of labour throughout the growing season and greater diversity of food and income sources. Evidence for higher productivity from intercropping through more efficient use of resources has been demonstrated (Andrews, 1972; De & Singh, 1979; Willey & Natarajan, 1978). Groundnutpigeonpea intercropping, which is prevalent in semiarid conditions of India on alfisols, does not produce good yields because of the traditional practice of having low pigeonpea density. Also, unsuitable genotype and poor arrangement of the crops often prove to be disadvantageous.