Aspects of seed production in 'grasslands maru' phalaris (Phalaris aquatica L.)

Studies on Maru phalaris seed production were conducted on a fertile silt loam soil at Lincoln University, Canterbury, New Zealand. Although the double ridge stage was reached by late July, shoot height gradually reached a maximum of 7cm above soil level by the third week of September but this was followed by rapid stem elongation suggesting that grazing should cease after this time. A row spacing of 45cm gave the highest seed yield, when compared with 15, 30 and 60cm. Seed number per unit area was the major determinant of seed yield and this was mainly determined by the number of side-branches per panicle and seeds per side-branch. The maximum seed yield of 683 kg/ha at the 45cm row spacing was achieved with 322 panicles/m2 averaging 21 side-branches per panicle and 7 seeds per side-branch. In narrower row spacing’s seed yield was limited by panicle size, while the widest row spacing (60cm) produced an insufficient number of very large panicles. Marking tillers of different sizes in September showed that the largest tillers (>4- 6mm) had 97% survival while medium (>2-4mm) and small tillers (2mm and less) had 78% and 15% survival respectively. The largest tillers produced the longest panicles (130mm) having 197 seeds per panicle whereas medium and small tillers produced panicles 98.6mm and 67.4mm in length having 177 and 97 seeds per panicle respectively. Analysis of seed growth and development showed that harvesting crops earlier than 21-24 days after anthesis (DAA) reduced thousand seed weight and viability. Delaying the harvest after 24 DAA, reduced seed yield due to seed shattering but had no detrimental effect on seed weight and viability. The optimum time to commence harvesting under the conditions experienced in this experiment was 21-24 DAA, when seed moisture was in the range of 40-42%, quality was high but shattering had not commenced in earnest