Timely harvest plays an important role in controlling rice cracking. Reduced whole-grain rice bring cracks caused by the loss of value and reduce the income of farmers. field experiments was conducted to study the effect of harvest time around the crack growth of rice plants Head rice yield in seven popular varieties (OM1490, OM2718, OM2517, OM4498, AG24, IR50404 and Jasmine) in three different locations in the two harvest years (2006-2008). Mekong Delta, Vietnam. The results show that cracking of rice has strong influence by the variety and harvest time about growing up | SECTION 1 Influence of harvesting time around grain maturity on rice cracking and head rice yield in the Mekong River Delta of Vietnam 5 SECTION 1. Influence of harvesting time around grain maturity on rice cracking and head rice yield in the Mekong River Delta of Vietnam ABSTRACT Timely harvesting plays an important role in controlling rice cracking. Reduced whole rice grain yield due to cracking causes the value loss and reduces the farmers income. Field experiments were carried out to study the effect of harvesting time around crop maturity on rice cracking and head rice yield for seven common rice varieties OM1490 OM2718 OM2517 OM4498 AG24 IR50404 and Jasmine in three different locations during two cropping years 2006-2008 in the Mekong River Delta Vietnam. The results showed that the rice cracking was strongly influenced by both the variety and time of harvesting around maturity. There was a general trend of increase in percentage of cracked rice with late harvesting in relation to estimated grain maturity date. The head rice yield also followed the same trend in response to delayed harvesting. A delay of 46 days reduced the head rice yield by an average and up to 50 . Similar trends were observed in both wet and dry seasons. The large varietal difference in percentage of cracked grain to on 6 days after maturity date indicated that the level of rice cracking caused by late harvesting time can be minimized by the selection of suitable varieties. INTRODUCTION Head rice yield which is defined as the weight percentage of rough rice that remains as head rice the kernels that are at least of the original kernel length after milling is considered as the main quality indicator because the broken rice has often half the commercial value of whole grain rice. It has been shown that timeliness of harvesting can influence milling yield significantly. Harvesting rice at crop maturity can give a maximum head rice yield Kester et al. 1963 Bal and Oiha 1975 . .
