Influence of planting geometry on photosynthetically active radiation interception and dry matter production relationships in pearl millet

A field experiment was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Center, Patancheru, India to study photosynthetically active radiation (PAR) interception and dry matter production relationships in pearl millet (Pennisetum americanum (L.) Leeke). Two pearl millet genotypes, BJ 104 (G1) and ICH 226 (G2) were sown at three planting geometries obtained by using combinations of row and plant spacings (S1: 37·5 cm × 26·6 cm; S2: 75·0 cm × 13·3 cm; S3: 150·0 cm × 6·6 cm) such that plant population was constant at 100 000 ha−1 in all treatments. Cumulative intercepted PAR was maximum (330 MJ m−2) in G2S2 and minimum (268 MJ m−2) in G1S3. Conversion efficiency values ranged from 1·87 g MJ−1 in G1S2 to 2·32 g MJ−1 in G2S3. Final above-ground dry matter followed the pattern of cumulative intercepted PAR and maximum dry matter (7·22 Mg ha−1) was produced by G2S2 while G1S3 produced minimum dry matter (4·97 Mg ha−1