Yield variation due to nipping of branches in combination with population manipulations in castor (Ricinus communis L.)

An experiment was conducted during rabi, 1998 to assess whether there will be any yield reduction, if the crop duration is shortened by growing the crop upto primaries/secondaries/tertiaries and whether this yield reduction can be compensated by manipulating the plant population, in castor (var. DCS-9). Different treatments tried were; keeping only primaties (P) with sppacing of 30 × 15, 30 × 30, 45 × 30, 60 × 30 cm, primary and secondary (P+S) branches with spacing of 45 × 30, 60 × 30, 90 × 30 cm and all the branches i.e. control with spacing of 90 × 30 cm. Dry matter, seed yield per plant were significantly more in control, but seed yield m⁻² was on par with 30 × 15 cm with primary, 60 × 30 cm with P + S and control plants than all other treatments. Harvest index was significantly more (59.4%) with P + S treatment under 60 × 30 cm which shows that assimilate translocation especially from stem reserves increased with closer spacing. Therefore, spacing of 60× 30 cm with branches upto secondaries is more advantageous in castor than the normal spacing of 90 × 30 cm with all branches and long duration. The crop duration was reduced by 50 days under the spacing of 30 × 15 cm with primaries, but the yield was on par with control. It is concluded that plant types of short duration with single spike should be developed in castor to fit into different cropping systems.