Performance of the main and ratoon crops of thirteen advanced rice selections under dry-seeded rainfed bunded conditions [in the Philippines]

IR 2823-399-5-6 (for 3 consecutive years) and IR 4722-36-1 significantly gave higher overall mean main crop yields of 4.65 and 3.60 t/ha respectively, over the others. They respectively matured in 134 and 133 days after seeding. The ratoon crop of IR 2058-78-1-32-3, IR 2863-38-1-2, IR 4722-36-1 and IR 2823-399-5-6 with respective overall yields of 2.57, 2.33, 2.09 and 1.92 t/ha and respective maturities of 79, 74, 79 and 68 days after main crop harvest looked very promising. Under abundant water supply condition IR 2058-78-1-3-2-3, IR 2863-38-1-2 and IR 4722-36-1 ratoon yielded 3 t/ha or more and just as good or even better than the main crop mainly due to better water supply which enhanced ratoon tillering or the 5 most suitable ratoon selections yielded average of over 90 percent that of the main crop. In the bunds with moderate and limited water supply, iron deficiency adversely affected ratoon performance moderately and severely, respectively. None of the ratoons lodged due to the frequent occurrence of extremely strong typhoons. The potentials of continuous ratooning (twice) appeared encouraging with very good water supply based on the performance of two early maturing varieties. The second ratoon had much higher yields and better grain characteristics than those of the first ratoon thus best demonstrating the feasibility of having a good ratoon only under adequate or abundant water supply condition where favorable crop nutritional factors apparently exist. Also, the presence of a high proportion of basal tillers might have somehow contributed to better anchorage and non-lodging tendency of the ratoons particularly under abundant water supply condition. The superior yielding selections found highly suitable both for dry-seeding and ratooning purposes generally exhibited such agronomic traits as being medium late maturing, relatively short statured, very high in tillering and panicle producing abilities, slightly lodging or non-lodging, average-sized in panicles and grains and having a high degree of tolerance to drought and iron deficiency. A ratoon crop appeared to have several advantages over a succeeding newly-established transplanted crop such as the elimination of the turn-around period and transplanting material and labor inputs, much reduced fertilizer input, extra ordinary lodging resistance and much shortened growth duration.