Stomatal density and stomatal length in relation to photosynthetic and transpirational behaviour of paddy rice varieties and their yield, and yield components.

水稻（Oryza sativa L. subsp.） 15个品种。日本属和亚种。包括从爱媛县现在和过去推荐的品种和超高产品种中选择的不同植物类型。利用便携式气体分析仪（Analytical Development Co. Ltd, England）连续数天每小时测量旗叶的光合速率和蒸腾速率。用旗叶背面和正面的牙釉质复制品测定气孔密度（<mm^(-2)>）和气孔长度（<mu>）。对叶面积、产量和产量构成因素也进行了研究。净光合速率的品种差异在天气晴朗的日子里表现得很明显，但在中午前后，即使在几个小时内，这种差异也会消失。许多品种的光合作用在上午10-12点达到最大。然而，在某些品种中，最大值发生在上午8-9点和下午2点，与太阳辐射强度无关。晴日品种光合速率与气孔导度呈高相关系数r= <0.783^(***)> 4。每小时测定气孔导度与气孔密度X气孔长度的关系。人们普遍认识到强烈的相关性，但在太阳辐射强度非常高的时候，这种相关性就消失了。认为品种的潜在气孔导度与气孔密度×气孔长度有本质关系。因此，发生水分胁迫的品种的气孔关闭会削弱其相关性。韩国超高产品种的气孔数量非常多，每旗叶的气孔数量在560万~ 710万个之间。这个数字是日本普通品种的2-2.5倍。旗叶总气孔长（=气孔数X气孔长）与穗粒数呈显著正相关（r= <0.784^(***)>），与产量呈显著正相关（r= <0.694^(**)>）。少

Fifteen varieties of paddy rice (Oryza sativa L. subsp. japonica and subsp. indica) including different plant types were chosen from current and past recommended varieties in Ehime prefecture and from super high yield varieties. Photosynthetic and transpiration rates of flag leaves were measured hourly for several days from heading through ripening periods using a portable gas analyzer (Analytical Development Co. Ltd., England). Stomatal density( <mm^(-2)> ) and stomatal length ( <mu> ) were examined with enamel repricas of abaxial and adaxial sides of the flag leaf. The leaf area, yield and yield components were also investigated.1. Varietal difference of net photosynthetic rate was clearly indicated on a fine day, although the difference disappeared when clouds arouse around at noon even in a few hours.2. Many varieties showed their maximum photosynthesis at 10-12 a.m. In some varieties, however, the maximum occurred at 8-9 a.m. and 2 p.m. independently of solar radiation intensities … More .3. A high correlation coefficient r= <0.783^(***)> was observed between varietal photosynthetic rates and varietal stomatal conductances on a fine day.4. Relations between stomatal conductance and stomatal density X stomatal length were investigated in each hour. Strong correlations were generally recognized, but they disappeared at hours when solar radiation exhibited very high intensities. The author considered that the potential stomatal conductance of varieties was essentially related with their stomatal density X stomatal length. Therefore, the correlation was weakened by stomatal closure of varieties which developed water stress.5. Super high yield Korean varieties had very many stomata,ranging from 5.6 to 7.1 millions per flag leaf in number. This number was 2-2.5 times as large as that of Japanese common varieties. Total stomatal length (= number of stomata X stomatal length) of the flag leaf was severely correlated with number of grains per head (r= <0.784^(***)> ), and with yield (r= <0.694^(**)> ). Less