Plant Population and Spatial Arrangement Effects in Monocrops and Intercrops in Rainfed Areas

Knowledge on the effect of populdtiorl changes and spatial arrangement in \nintercropping situations unlike for pure cropss is very limited. The paper \ndescribes some aspects of total population pressures proportional populations \nand relative space allocations which are highly interrelated in intercropping. \nIt is pointed out that unless their effects are quantified independent of one . \nanothers clear understanding of the basic relationships between various crops \nin mixtures can not be established. The response of crops, sorghum, pearl millet, \nragi, sunflower, safflower etc, , to changes in geometry of planting at constant \npopulation, such as wide row widths and pairing of rows, which may increase the \nscope for intercropping is discussed. Under moisture limiting conditions and no \nN fe r t ilisa t io n , doubling the row width of sorghum sole resulted in 15,8 - 93.2% \nhigher yield depending on soil type, Widening the row width of base crop, without \nreducing its population, may allow an increase in the total population pressure of \nthe system which may in turn give greater intercropping benefits. The advantages \nof grouping or pairing of rows in de fic it moisture conditions as an yield improvement \npractice in sole crops and as a method to alleviate competition between the \nassociated crops in mixtures is discussed with examples. Three crop intercropping \nwith widely spaced pigeonpea showed 66% advantage compared to 45% in the \ncase of two crop intercropping. Possible spatial arrangement of crops for intercropping \nand sequential cropping to suit broad ridge and furrow systems \nof cultivation is discussed