玉米自交系吐丝期叶片光合参数与其耐旱性的关系

从玉米自交系吐丝期光合特性适应干旱环境的角度，探索玉米自交系的耐旱性。2012年在土默川平原灌区和河套平原灌区以及2013年河套平原灌区，利用耐旱性不同的51个玉米自交系，在吐丝期采取干旱胁迫处理，研究分析了叶片光合相关参数对干旱胁迫的响应及其与耐旱性的关系。结果表明，玉米自交系在吐丝期干旱胁迫与正常灌溉条件下P_n、T_r、G_s、C_i、F_v/F_m、Φ_PSII和SPAD的相对值与其耐旱系数呈极显著正相关，WUE相对值与耐旱系数呈极显著负相关，而q_N和q_P的相对值与耐旱系数不相关；上述8个叶片光合参数与耐旱系数的逐步回归分析表明，P_n、WUE、F_v/F_m、Φ_PSII和SPAD相对值与耐旱系数在0.01水平显著相关，P_n、WUE、SPAD相对值对耐旱系数有直接贡献，而F_v/F_m和Φ_PSII对耐旱系数起间接作用。通过上述5个显著相关光合参数将两年三地表现一致的32份自交系的抗旱性分为3类，第1类8份(H201、H21、英64、吉842、早49、吉8415、东46和沈137)属于耐旱性强的；第2类15份属于耐旱性较强的；第3类9份属于耐旱性弱的，此结果与对应的自交系产量差异分类结果相一致。因此，玉米自交系吐丝期P_n、WUE、F_v/F_m、Φ_PSII、SPAD的相对值和耐旱系数可作为其耐旱性评价指标。建立了3类耐旱性玉米自交系吐丝期P_n、WUE、F_v/F_m、Φ_PSII、SPAD的相对值与耐旱系数的回归关系，并明确了其阈值范围。

Relationship between Leaf Photosynthetic Parameters and Drought Resistance at Silking Stage in Maize Inbred Lines

To explore drought resistance of maize inbred lines, based on leaf photosynthetic parameters at silking stage, we treated 51 maize inbred lines with drought stress at silking stage in Humochuanpingyuanguanqu and Hetaopingyuanguanqu in 2012 and 2013 to analyze response of leaf photosynthetic parameters to drought stress and the relationship between photosynthetic parameters and drought tolerance. The result indicated that at silking stage, no matter under drought and the condition of irrigation, P_n, T_r, G_s, C_i, F_v/F_m, Φ_PSII, and SPAD had a significant and positive correlation with drought resistance coefficient, WUE had a significant and negative correlation with it, while qN and qP had no correlation with it. Stepwise regression analysis on the eight leaf photosynthetic parameters above showed that P_n, WUE, F_v/F_m, Φ_PSII, and SPAD significantly correlated with drought resistance coefficient at P < 0.01. P_n, WUE and SPAD directly contributed to drought resistance coefficient, while F_v/F_m and Φ_PSII contributed indirectly. Thirty-two maize inbred lines were classified into three groups based on different drought resistance, group 1 with the highest drought resistance contained eight inbred lines (H201, H21, Ying 64, Ji 842, Zao 49, Ji 8415, Dong 46, and Shen 137), group 2 with the higher drought resistance contained fifteen lines and group 3 with the lowest drought resistance contained nine lines. The grouping result was consistant with that of yield classification.Therefore, at silking stage, P_n, WUE, F_v/F_m, Φ_PSII, SPAD, and drought resistance coefficient can be used as drought resistance evaluation indexes established for the three groups of maize inbred lines. Regression relationship was between P_n, WUE, F_v/F_m, Φ_PSII, SPAD, and drought resistance coefficient at silking stage, and the threshold values were confirmed.