Seedling Conditioning for Improved Outplanting Survival in Chir Pine (<I>Pinus roxburghii</I> Sargent)

Abstract

In two experiments on conditioning of chir pine (Pinus roxburghii Sargent) laid out to raise seedlings for monsoon and winter plantings, seven month old seedlings were subjected to three undercutting depths (7 cm, 12 cm and 17 cm) followed by three wrenching regimes (control, weekly and biweekly) and combination of lateral and box pruning (control, lateral pruning at 6 cm and box pruning at 6 cm from seedlings) and three irrigation intensities (irrigation just after fortnight wrenching, 12 hours after fortnight wrenching and 18 hours after fortnight wrenching). The experiments were laid out in split-split plot design with two replications. Treated plants on providing a rest period of four weeks after final wrenching were outplanted in field at 1.5 m × 1.5 m spacing. Different treatment combinations exhibited varying responses on survival of the outplanted seedlings, recorded after one year. Wrenching frequency significantly improved survival of seedlings. Maximum and highly significant survival was recorded in seedlings wrenched weekly followed by those wrenched fortnightly. Undercutting depth also significantly influenced outplanting survival. Maximum survival was recorded for seedlings undercut at 12 cm followed by those undercut at 17 cm. The results of treatments-lateral pruning, box pruning and irrigation showed non-significant effects on field survival rates.