Investigation on weed density and yield in regulated deficit irrigation in dry seeded rice (Fajr cultivar)
2005
A`rab Zadeh, Behruz | Erphani, A`bd Ol-Rahman | Sharifi, Moslem Mohammad
In certain site if the world for reason of water deficiency especially on time of rice cultivation the farmer grow dry seeded rice. May be there is some usfule aspect for this method including saving for water and labour in order to non-prepration rice nursery, but it has many difficulties and weed problem are the most one. For investigation on weed density on this method of rice cultivation, we conducted a trial at Amol (Deputy of Rice Research Institute) with 7 treatments and 3 replication in 2002 and repeated it in 2003 as follow: 1) seeding on dried soil and regulated 5cm water depth one month after seeding 2) Treatments was as above thath mentioned, but 3cm water depth. 3,4) Irrigation one month after of seeding with 0 to 5 and 0-3cm water depth in rotation “respectivly†5,6) Irrigation one month after seeding and then regulated water depth 0-3 and 0-5cm in rotation â€respectivelyâ€. 7) Irrigation one month after seeding and flooding up to 15 days regulaated 5cm water depth and then saturated over time.SO, two days before of doing irrigation treatments we used Propanil mixed with Bentazon. Six weeks after seeding the impottant weeds has been counted including water grass(Echinochlea cros-galli) and smal flowere (Crperus difformis) with quadrate 0.5 أ— 0.5 on one squar meter per each plot. Then timing of spent for hand weeding recorded on each plot. Mean comparison of weeds showed that althougt “ T1†had been the lowest weed density but weed growing in al treatments were high and it is not accepted. This position for smal flower was the same. The reason of this result is connected to late start of irrigation. So, seed of weeds has been grown gradually with getling warm the weather and continued all the season growing. The mean of time of hand weeding for removing of weeds that has been grown one month after seeding was 785.5 hour per hectare that in comparison with transplanted rice is very high and it make more expense for rice prodoction.
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